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The big advantage of refractory high entropy alloys (RHEAs) is their strength at high temperatures, but their big disadvantage is their brittleness at room temperature, which prevents their machining. There is a great need to classify the alloys in terms of brittle-ductile (B-D) properties, with easily obtainable ductility indices (DIs) ready to help design these refractory alloys. Usually, the DIs are checked by representing them as a function of fraction strain, ε. The critical values of DI and ε divide the DI—ε area into four squares. In the case of a successful DI, the points representing the alloys are located in the two diagonal opposite squares, well separating the alloys with (B-D) properties. However, due to the scatter of the data, the B-D separation is not perfect, and it is difficult to establish the critical value of DI. In this paper, we solve this problem by replacing the fracture strain parameter with new DIs that scale with the old DIs. These new DIs are based on the force constant and amplitude of thermal vibration around the Debye temperature. All of them are easily available and can be calculated from tabulated data. [ABSTRACT FROM AUTHOR]

The Mercury Sulphohalides have attracted significant attention in the fields of solar cells and thermoelectric applications. This study delves into the fundamental characteristics, including structural, elasticity, electronic behavior, phonon stability, optical properties, and transport features of AgHgSZ (Z = Br, I) through computational simulations based on Density Functional Theory (DFT) using WIEN2k software. Meticulous calculations of the phonon band structure ensure dynamic stability. The semiconductor nature with indirect band gaps (1.833 eV and 1.832 eV) for Mercury Sulphohalides (Br, I), as revealed by their band structures, suggests diverse photovoltaic and transport applications. Mechanical assessments show stable ductility for AgHgSBr and brittleness for AgHgSI, along with anisotropy and resistance to scratching. Optical properties exhibit anisotropy and significant UV absorption. Analysis of effective masses, exciton binding energy, and exciton Bohr radius suggests low exciton binding energy and classification under Mott-Wannier excitons. Positive thermopower results indicate holes as the predominant charge carriers in AgHgSBr and AgHgSI materials. Moreover, essential thermoelectric factors are examined, revealing the compounds' potential for thermoelectric applications. Notably, the figure of merit (ZT) at 300 K for AgHgSBr and AgHgSI are calculated to be 0.41 and 0.13, respectively. While these values are low at 300 K, they indicate promising potential for thermoelectric applications at higher temperatures. In summary, this investigation provides valuable understanding into the photovoltaic and thermoelectric properties of AgHgSZ (Z = Br, I) materials, potentially paving the way for further exploration in this domain. [ABSTRACT FROM AUTHOR]

The interface connects the reinforced phase and the matrix of materials, with its microstructure and interfacial configurations directly impacting the overall performance of composites. In this study, utilizing seven atomic layers of Mg(0001) and Ti(0001) surface slab models, four different Mg(0001)/Ti(0001) interfaces with varying atomic stacking configurations were constructed. The calculated interface adhesion energy and electronic bonding information of the Mg(0001)/Ti(0001) interface reveal that the HCP2 interface configuration exhibits the best stability. Moreover, Si, Ca, Sc, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, Mo, Sn, La, Ce, Nd, and Gd elements are introduced into the Mg/Ti interface layer or interfacial sublayer of the HCP2 configurations, and their interfacial segregation behavior is investigated systematically. The results indicate that Gd atom doping in the Mg(0001)/Ti(0001) interface exhibits the smallest heat of segregation, with a value of −5.83 eV. However, Ca and La atom doping in the Mg(0001)/Ti(0001) interface show larger heat of segregation, with values of 0.84 and 0.63 eV, respectively. This implies that the Gd atom exhibits a higher propensity to segregate at the interface, whereas the Ca and La atoms are less inclined to segregate. Moreover, the electronic density is thoroughly analyzed to elucidate the interfacial segregation behavior. The research findings presented in this paper offer valuable guidance and insights for designing the composition of magnesium-based composites. [ABSTRACT FROM AUTHOR]

Depending on the 3D-printing orientation, the anisotropy of the elastic characteristics of the Inconel 625 alloy generated with selective laser sintering from powders is investigated. The impact of the original powder combination and the following heat treatment (post-printing treatment) on the anisotropy of the alloy elastic characteristics is assessed. As demonstrated, the suggested treatments can lessen the anisotropy of the alloy elastic characteristics. Based on knowledge of the elastic constants of the single crystal and x-ray texture features, the results of a theoretical estimation of the elastic and shear moduli, Poisson’s ratio, and their anisotropy in the horizontal and vertical directions of 3D printing are provided. As demonstrated, the obtained theoretical values differ by 6–10% from the corresponding experimental values. The calculated stress–strain state can be more accurately calculated with the use of the estimated elastic characteristics and their anisotropy. The strategy for 3D-printing complicated components from Inconel 625 alloy may be made more effective.

Abstract The Mercury Sulphohalides have attracted significant attention in the fields of solar cells and thermoelectric applications. This study delves into the fundamental characteristics, including structural, elasticity, electronic behavior, phonon stability, optical properties, and transport features of AgHgSZ (Z = Br, I) through computational simulations based on Density Functional Theory (DFT) using WIEN2k software. Meticulous calculations of the phonon band structure ensure dynamic stability. The semiconductor nature with indirect band gaps (1.833 eV and 1.832 eV) for Mercury Sulphohalides (Br, I), as revealed by their band structures, suggests diverse photovoltaic and transport applications. Mechanical assessments show stable ductility for AgHgSBr and brittleness for AgHgSI, along with anisotropy and resistance to scratching. Optical properties exhibit anisotropy and significant UV absorption. Analysis of effective masses, exciton binding energy, and exciton Bohr radius suggests low exciton binding energy and classification under Mott-Wannier excitons. Positive thermopower results indicate holes as the predominant charge carriers in AgHgSBr and AgHgSI materials. Moreover, essential thermoelectric factors are examined, revealing the compounds’ potential for thermoelectric applications. Notably, the figure of merit (ZT) at 300 K for AgHgSBr and AgHgSI are calculated to be 0.41 and 0.13, respectively. While these values are low at 300 K, they indicate promising potential for thermoelectric applications at higher temperatures. In summary, this investigation provides valuable understanding into the photovoltaic and thermoelectric properties of AgHgSZ (Z = Br, I) materials, potentially paving the way for further exploration in this domain.

Experimental investigation of the elastic behaviours of lacustrine shales remains sparse, although they play an essential role in source rock evaluation, unconventional reservoir exploration and development, and the seal integrity evaluation for geological storage of CO2 and nuclear waste disposal. We make the ultrasonic velocity measurement of 63 organic‐rich shale samples (Chang 7, Qingshankou and Lucaogou formation) from three typical lacustrine basins in China. It is found that the P‐ and S‐wave velocity of Chang 7 and Qingshankou shale corresponding to the fresh‐brackish lacustrine depositional environment is mainly impacted by the clay and organic matter content, whereas their elastic anisotropic magnitude is mostly influenced by clay content. The P‐ and S‐wave velocities of Lucaogou shale corresponding to the saline lacustrine depositional environment are mainly affected by the total organic carbon and porosity and exhibit weak anisotropy linked to organic matter enrichment. Exponential law well captures the relationship between anisotropic magnitude and velocity perpendicular to bedding for both saline and fresh‐brackish water lacustrine shales, although there exists notable discrepancy, particularly at low velocities. The disparity in elasticity between laminations has a profound impact on the magnitude of elastic anisotropy and shapes the trend of velocity variations. [ABSTRACT FROM AUTHOR]

The crystal structure and elastic properties of chromium tetraboride (CrB4) were investigated by pseudopotential plane-wave methods within the Perdew-Burke-Ernzerhof (PBE) form of generalized gradient approximation (GGA). The calculated equilibrium structural parameters of Pnnm-CrB4 are in good agreement with the available experimental data and other theoretical results. Moreover, the elastic constants Cij, bulk modulus B, shear modulus G and elastic modulus E under high pressure were calculated, and the toughness and brittleness of Pnnm-CrB4 under high pressure were analyzed with the Poisson ratio σ and B / G. To study the elastic anisotropy of Pnnm-CrB4 in detail, the anisotropic factors A1, A2, A3 for shear and Ba, Bb, Bc for the directional bulk modulus were also calculated. The Vickers hardness HV of Pnnm-CrB4 was estimated at the same time. Finally, the total and partial density of states of Pnnm-CrB4 under high pressure were studied so as to have a better understanding of the mechanical and elastic properties of Pnnm-CrB4. [ABSTRACT FROM AUTHOR]

Depending on the 3D-printing orientation, the anisotropy of the elastic characteristics of the Inconel 625 alloy generated with selective laser sintering from powders is investigated. The impact of the original powder combination and the following heat treatment (post-printing treatment) on the anisotropy of the alloy elastic characteristics is assessed. As demonstrated, the suggested treatments can lessen the anisotropy of the alloy elastic characteristics. Based on knowledge of the elastic constants of the single crystal and x-ray texture features, the results of a theoretical estimation of the elastic and shear moduli, Poisson's ratio, and their anisotropy in the horizontal and vertical directions of 3D printing are provided. As demonstrated, the obtained theoretical values differ by 6-10% from the corresponding experimental values. The calculated stress-strain state can be more accurately calculated with the use of the estimated elastic characteristics and their anisotropy. The strategy for 3D-printing complicated components from Inconel 625 alloy may be made more effective. [ABSTRACT FROM AUTHOR]

Polymer films have broad applications in different industries with specific requirements for their optical and mechanical properties. In mass production, processing conditions during film formation that apply forces and motions in various directions to the film tend to manifest preferred molecular chain orientation in the film microstructure, which unavoidably produces optical and mechanical anisotropies. In this paper, we investigate the effect of such macromolecular orientations on the optical and mechanical anisotropies of several polymer films, including polystyrene, poly(methyl methacrylate), poly(ethylene terephthalate), poly(ethylene naphthalate), poly(ether ether ketone), poly(ether sulfones), poly(ethylene chlorotrifluoroethylene), poly(phenylsulfone), and polycarbonate, at temperatures well below their respective glass transitions (Tg). The film mechanical responses, including elasticity, yielding, and post-yield behaviors, were obtained for the in- and out-of-plane directions utilizing tensile and nanoindentation testing methods, respectively. In addition, the net chain orientation within the films was evaluated by birefringence through analyzing the film optical refractive indices, which were verified and complemented by wide-angle X-ray scattering (WAXS) measurements. The results reveal a considerable quantitative correlation between the birefringence and the degree of elastic anisotropy and a qualitative correlation between the chain orientation and the film post-yield tensile instability (necking). These observations corroborate the interrelationship between the microstructure of polymer films and their optical and mechanical properties. In addition, they emphasize that process conditions can be selected to tune the optical and mechanical anisotropies to best serve the material performance in specific devices. We also propose an empirical equation to approximate the out-of-plane film stiffness based upon the optical and in-plane mechanical properties. [ABSTRACT FROM AUTHOR]

The big advantage of refractory high entropy alloys (RHEAs) is their strength at high temperatures, but their big disadvantage is their brittleness at room temperature, which prevents their machining. There is a great need to classify the alloys in terms of brittle-ductile (B-D) properties, with easily obtainable ductility indices (DIs) ready to help design these refractory alloys. Usually, the DIs are checked by representing them as a function of fraction strain, ε. The critical values of DI and ε divide the DI—ε area into four squares. In the case of a successful DI, the points representing the alloys are located in the two diagonal opposite squares, well separating the alloys with (B-D) properties. However, due to the scatter of the data, the B-D separation is not perfect, and it is difficult to establish the critical value of DI. In this paper, we solve this problem by replacing the fracture strain parameter with new DIs that scale with the old DIs. These new DIs are based on the force constant and amplitude of thermal vibration around the Debye temperature. All of them are easily available and can be calculated from tabulated data.

The effect of anisotropy of elastic energy on electron–phonon relaxation in potassium crystals is studied. The spectrum and polarization vectors of phonons are calculated, and the contributions of all vibrational modes to the drag thermopower and electrical resistivity of potassium crystals are analyzed. It is shown that the contribution of the t2 slow quasi-transverse mode to these effects, which was not previously taken into account, at temperatures much lower than the Debye temperature , exceeds the contribution of longitudinal phonons by an order of magnitude. However, at high temperatures (), the contribution of longitudinal phonons to the electrical resistivity turned out to be 4 times greater than the total contribution of electron relaxation in the fast and slow quasi-transverse modes. By comparing the calculated total thermopower of potassium crystals with different dislocation densities with experimental data, the constants of the coupling of electrons with the shear components of vibrational modes is determined. For samples with different dislocation densities, the contribution of shear waves to the drag thermopower is 4–6 times greater than the contribution of longitudinal phonons. It is established that the maximum values of drag thermopower in perfect potassium crystals at low temperatures do not depend on the electron–phonon relaxation constants, but are completely determined by the second-order elastic moduli, crystal density, and electron density. In this case, the contributions of various modes to the drag thermopower turn out to be proportional to the ratio of the heat capacities of the individual modes. It is shown that shear waves make a significant contribution to the electrical resistivity of potassium crystals at low temperatures . It is 4 times greater than the contribution to the electrical resistivity from longitudinal phonons and should be taken into account when analyzing the electrical resistivity of potassium. The distribution of phonons most efficient for electrical resistivity is determined, and the effect of the inelasticity of electron–phonon scattering on the electrical resistivity and drag thermopower of potassium crystals at low temperatures is analyzed. It is shown that its maximum is at and the energy of the most efficient phonons is distributed in the interval . The effect of anisotropy of elastic energy on the electron–phonon mutual drag and the electrical resistivity of potassium crystals at low temperatures is considered. In the hydrodynamic approximation, the momentum exchange between the electron and three phonon fluxes corresponding to the three branches of the vibrational spectrum is analyzed. The actual mechanisms of phonon momentum relaxation are taken into account: scattering at sample boundaries, dislocations, and in phonon–phonon umklapp processes. It is shown that, in the limiting case of strong mutual drag, the drift velocities of phonons of all polarizations and electrons are close and determined by the total rate of phonon relaxation in resistive scattering processes. [ABSTRACT FROM AUTHOR]

The spectrum and polarization vectors of phonons in alkali and noble metals belonging to cubic crystals with positive anisotropy of elastic moduli are calculated. They are compared with the results for dielectric crystals. It is shown that the anisotropy of the spectrum in them is significantly higher than in dielectric crystals such as Ge and Si. The polarization vectors of the slow t2 mode in them have an anomalously large longitudinal component compared to Ge and Si crystals. In Na, Li, and K crystals, it reaches 70, 60, and 30%, respectively. This leads to a significantly greater effect of the slow t2 mode on electron–phonon relaxation and drag thermopower in alkali metals. Isoenergetic surfaces are calculated, and the features of phonon propagation in alkali and noble metals are analyzed. Their most interesting feature is the effect of focusing on the propagation of longitudinal phonons in alkali metals. For phonon wave vectors in the {100} planes, the directions of group velocities for all alkali metals are close to [101]. Estimates have shown that, for Na, Cs, and K crystals, more than 90, 86, and 79% of phonons, respectively, with wave vectors in the {100} plane propagate in the [101] directions. This effect can be used to obtain plane-parallel phonon beams from a point source of longitudinal vibrations, as well as for other technical applications. The effect of anisotropy of elastic energy on the density of phonon states in alkali metals is analyzed. The results for metallic and dielectric crystals of cubic symmetric are compared. The ranges of angles corresponding to phonon focusing and defocusing are determined. The phonon flux enhancement factors are calculated and compared for metallic and dielectric crystals. The dependences of the types of curvature of isoenergetic surfaces of acoustic modes in alkali and noble metals on the values of anisotropy parameters are analyzed. [ABSTRACT FROM AUTHOR]

Locking effects can be a major concern during the numerical modelling of elastic materials, especially for large strains. Those effects arise from volumetric constraints such as incompressibility or anisotropic effects of the underlying material class. One particular solution strategy is to employ mixed formulations, which provide solutions tailored to the specific locking phenomena at hand. While being in general powerful, one drawback of such solution strategies is that the provided strategy to overcome locking is often tied or limited to some specific topological type of finite elements and thus forfeiting generality. Contrary the Virtual Element Method (VEM) benefits by definition from allowing arbitrary element shapes and number of nodes at element level. A variety of approaches for the treatment of locking phenomena for hyperelastic material is formulated in this contribution for the Virtual Element Method with a low order ansatz. Key ingredient to the implementation of multi-field mixed principles in VEM is the consideration of only one constant variable per field and one corresponding Lagrange multiplier over the entire virtual element. Hereby the stabilization contribution utilizes the mixed formulation but shares the element-wise constant variable with the projection part of the virtual element. A direct consequence of this rather simple implementation strategy is the combination of powerful mixed formulations with a computational approach that is able to treat general element shapes. The proposed formulations are tested with regard to structured mesh at standard examples in computational mechanics as well as at specific computational engineering applications where also unstructured meshes are utilized. [ABSTRACT FROM AUTHOR]

An analytical solution for residual stresses and their energy in an elastically anisotropic two-component plate structure, where the components have an identical type of elastic anisotropy, identical or proportional elastic constants and coinciding principal axes of elastic anisotropy is obtained. The obtained solution has been applied to analyze the anisotropy of the elastic energy of such crystalline structures as the raft structure γ/γ' of single-crystal nickel-base superalloys, multilayer erosion-resistant nanocoatings ZrN/CrN and single-layer coatings of various types. It has been shown that the factor of minimizing the elastic energy of residual stresses has a significant effect on the crystallographic orientation of the interface in multilayer structures and the direction of axis of the growth texture axis of coatings. [ABSTRACT FROM AUTHOR]

The effect of pressure and temperature on acoustic and thermodynamic properties of cubic CsNbO3 (CNO) has been demonstrated using first principles method. The high values of velocity, impedance, and sound intensity exhibit CNO's potential acoustic applications. CNO is found thermodynamically unstable at 0 GPa, though it becomes stable at 20 GPa. The high Debye, melting temperatures, heat capacity, low thermal expansion coefficient, and thermal conductivity substantiate the compound can be used as thermal management material. The low value of the Gruneisen parameter corresponding to low anharmonicity proclaims higher lattice thermal conductivity of the material. The monotonic decline of lattice thermal conductivity with temperature is observed in CNO. The significant response of enthalpy, entropy, free energy, constant pressure heat capacity, and constant volume heat capacity with pressure and temperature have also been analyzed, which can be supportive for future investigations of CNO through experiments and theories.

The interface connects the reinforced phase and the matrix of materials, with its microstructure and interfacial configurations directly impacting the overall performance of composites. In this study, utilizing seven atomic layers of Mg(0001) and Ti(0001) surface slab models, four different Mg(0001)/Ti(0001) interfaces with varying atomic stacking configurations were constructed. The calculated interface adhesion energy and electronic bonding information of the Mg(0001)/Ti(0001) interface reveal that the HCP2 interface configuration exhibits the best stability. Moreover, Si, Ca, Sc, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, Mo, Sn, La, Ce, Nd, and Gd elements are introduced into the Mg/Ti interface layer or interfacial sublayer of the HCP2 configurations, and their interfacial segregation behavior is investigated systematically. The results indicate that Gd atom doping in the Mg(0001)/Ti(0001) interface exhibits the smallest heat of segregation, with a value of −5.83 eV. However, Ca and La atom doping in the Mg(0001)/Ti(0001) interface show larger heat of segregation, with values of 0.84 and 0.63 eV, respectively. This implies that the Gd atom exhibits a higher propensity to segregate at the interface, whereas the Ca and La atoms are less inclined to segregate. Moreover, the electronic density is thoroughly analyzed to elucidate the interfacial segregation behavior. The research findings presented in this paper offer valuable guidance and insights for designing the composition of magnesium-based composites.

This study investigates and compares the physical properties of various UX2 (X = O, N, C, Si and S) nuclear fuels using a combination of Density Functional Theory (DFT) and Hubbard U correction parameter (U) to accurately model the electronic structure and account for strong correlation effects among 5f orbital electrons. Spin-polarized DFT + U method is employed to optimize the structures of the considered compounds. The computational analysis reveals that UO2 and UN2 exhibit Mott-insulating properties, while the remaining UX2 compounds demonstrate metallic nature. To assess the mechanical aspects of these materials, the study evaluates their mechanical stability, Vickers hardness and machinability index through calculations of elastic constants. Notably, all the UX2 fuels are found to be mechanically stable and possess ductility. Both the two-dimensional (2D) and three-dimensional (3D) depictions of the elastic moduli for the analyzed solid fuels demonstrate the presence of elastic anisotropy. The famous Slack's equation is used to determine the lattice thermal conductivity of the UX2 fuels, providing valuable insights into their thermal properties. Among the investigated materials, UC2 exhibits the highest values of Debye temperature and lattice thermal conductivity, which amount to 412 K and 15.73 Wm−1 K−1 at 300 K, respectively. Furthermore, UN2 demonstrates the highest melting temperature. Among the compounds under investigation, UC2 and UN2 fuels exhibit the most minimal thermal expansion and the greatest heat capacity. Based on these findings, UC2 and UN2 emerge as promising alternative fuel materials to UO2 for potential use in nuclear power reactors. This research contributes to the ongoing efforts in identifying alternative fuel materials.

The structure, elastic properties, and thermodynamic properties of cubic boron arsenide (c‐BAs) under high temperature and high pressure are studied based on first‐principles calculations. The obtained equilibrium structure and mechanical properties are in good agreement with other theoretical results. First, the phonon dispersion spectra at zero pressure and high pressure are calculated. The results show that c‐BAs is dynamically stable under pressure of 0–110 GPa. Second, the lattice constants, elastic constants, Young's modulus, bulk modulus, shear modulus, Poisson's ratio, B/G, sound velocity, and Debye temperature of c‐BAs under zero pressure and high pressure are calculated. c‐BAs are predicted to be unstable above 112.3 GPa in accordance with the elastic stability criterion. Furthermore, it is indicated by the calculated B/G ratio that c‐BAs is brittle at zero GPa and begins to tend to be ductile as pressure rises to 46.4 GPa. The calculated elastic anisotropy coefficients indicate that c‐BAs has elastic anisotropy. The thermodynamic properties of c‐BAs are investigated at high temperatures and pressures by combining generalized density function theory and the quasiharmonic Debye model. It is suggested by the calculated elastic and thermodynamic properties that c‐BAs can be used as candidate structures for the fabrication of efficient solar cells and thermoelectric materials. [ABSTRACT FROM AUTHOR]

Elastic anisotropy of shales is critical to accurate constraints for rock physical models, quantitative interpretation and hydraulic fracturing. However, the causes of elastic anisotropy of shales are very complicated, and the understanding of how multiple influence factors affect the elastic anisotropy of shales is still not clear. Hence, the orthogonal experiment, as an effective multiple factors experimental method, is adopted in this study to analyze the effect of multiple factors for shale elastic anisotropy. Three factors, clay content, organic matter (OM) content and compaction stress are selected as independent variables, the orthogonal test table L16(4³) with four levels for each factor is adopted. According to the designed orthogonal table, sixteen artificial shales are constructed based on the cold-pressing method, and all the dry artificial shales are measured by the ultrasonic measurements. The influence of each factor on the elastic anisotropy and the sensitivity orders of three factors are obtained using the range analysis. The orders of sensitivity for selected factors follow the sequence clay content > compaction stress > OM content for velocity anisotropy parameters. The compaction mechanism of artificial shales is also discussed by the compaction factor, which are positively correlated with the velocity anisotropy parameters. The clay platelets orientation distribution function (ODF) of samples is evaluated by a theoretical model, the ODF coefficients are significantly affected by the clay content and compaction stress, and W200 are much more sensitive to these factors than W400. The results can provide a critical rock physics basis for quantitative interpretation and reservoir prediction of the low-maturity or maturity shale reservoir. [ABSTRACT FROM AUTHOR]

Interpenetrating phase metal/ceramic composites (IPC) offer an optimum combination of strength, stiffness, wear resistance, and thermal properties. Ceramic preforms fabricated by freeze-casting are optimum for IPC fabrication due to the lamellar open porous structure of the preforms and their excellent permeability for melt infiltration. While the thermal properties of IPCs based on freeze-cast ceramic preforms have been sporadically studied, to the best of our knowledge, this is the maiden work where the influence of ceramic preform's freeze-casting temperature and preform anisotropy on the thermal expansion behavior of the resulting IPC has been systematically investigated. Preforms were freeze-cast at two different temperatures, − 10, and − 30 °C. Thermal expansion behavior was studied by thermal cycling at a slow rate between room temperature and 500 °C. Both thermal strain and coefficient of thermal expansion (CTE) were determined as a function of temperature along the freezing direction and along a direction orthogonal to it. Elastic anisotropy present in the composite samples was estimated prior to the thermal expansion measurements using a non-destructive ultrasonic technique. The results showed that the lamellar anisotropic preform structure and corresponding elastic anisotropy had a strong influence on the composite's thermal expansion behavior—generally, the highest thermal strain and CTE were achieved along the most compliant direction. The measured CTE values were compared with relevant analytical models. [ABSTRACT FROM AUTHOR]

The recently proposed transition metal polynitride, tetragonal TiN 8 featured infinitely armchair-like N chains, has attracted much attention for its larger high-energy density value than the well-known TNT explosive. However, as a typical transition metal nitrogen-rich compounds with outstanding mechanical properties, the electronic properties and structure-mechanical relations remain to be further explored. Here, we performed first principles calculations that investigate the thermodynamic stabilities of tetragonal TMN 8 (TM = Ti, Zr, Hf), and fully studied the mechanical and elastic anisotropic behavior of these materials. In particular, the stress-strain relations and the related evolutions of chemical bonding were systematically studied. The uniaxial ultra-incompressible nature of these TMN 8 has been demonstrated by the calculated elastic moduli, originated from the strong N–N covalent bonds along the c -axis. Under (110) [ 1 1 ‾ 0 ] shear direction, the TMN 8 exhibits an abnormally large breaking shear strain that produces a strong shear strength exceeding 40 GPa. This unusual behavior stems from the strongly and stably 3D structure framework consisted of strong N–N covalent bonds in infinite N chains connected by Ti atom through Ti–N covalent bonds in Ti–N hexahedrons. These obtained findings explicate the crystal structural configurations and chemical bonding characters that are responsible for the mechanical properties of TMN 8 and provide insights for understanding other transition metal polynitrides. [ABSTRACT FROM AUTHOR]

Al5W compound is a promising high-temperature material due to the high melting point, good mechanical properties and good corrosion resistance. However, the structural feature of Al5W remains controversy. To solve these problems, we apply the first-principles calculations to study the structural stability, elastic properties, elastic anisotropy and melting point of Al5W. Four possible Al5W phases are discussed based on the similar A5B-type structure. The results show that two novel Al5W phases: orthorhombic (Cmma) and rhombohedral (R-3c) structures are predicted. The hexagonal (P6/mmm) Al5W has better thermodynamic stability. The bulk modulus of the predicted Cmma and R-3c phases is close to the known P63 phase. The result demonstrates the brittle behavior of the P63 Al5W. However, the hexagonal (P6/mmm) Al5W shows lower deformation resistance in comparison to the other Al5W. Importantly, the hexagonal (P63) Al5W has the stronger degree of shear anisotropy along the (100) and (010) plane. But the orthorhombic (Cmma) Al5W has the stronger degree of shear anisotropy along the (001) plane compared to the other three Al5W. Finally, the calculated melting point follows the order of P63 > R-3c > Cmma > P6/mmm. Naturally, the Al5W shows high melting point is related to the vibration of Al atom and Al–Al bond.

Introduction: Current research has mostly simplified CFRP components as isotropic media or homogenized them as anisotropic media, which fails to present the actual acoustic propagation behavior inside the CFRP components and restricts the accuracy of decoupling sound line tracking results and defect feature information.Method: Based on clarifying the influence of fiber direction on the spatial distribution of CFRP elastic properties, this paper proposes an acoustic modeling method for CFRP multi-directional plates considering the coupling effect of multi-layer structure and elastic anisotropy.Results: There are two main innovations: 1. The model is optimized using the Voigt representation method, which can quantitatively characterize the elastic anisotropy of any homogeneous material with a 6 × 6 elastic stiffness matrix containing 21 independent elastic constants. In this paper, the elastic stiffness matrix only includes five independent elastic constants; 2. Finite element simulation is used to analyze the propagation rules of ultrasonic waves inside CFRP and compare the detection methods with or without sound coupling layer.Discussion: The acoustic characteristics of the sound coupling layer are changed to find the optimal coupling method, reduce the refraction of ultrasonic waves in the specimen layer, and make the sound line path more accurate.

A 2–1–2 composite with two single-crystal components is studied for the first time to highlight large hydrostatic piezoelectric coefficients dh* and gh*, figure of merit dh*gh*, and electromechanical coupling factor kh*. Each 2–1–2 composite contains layers of domain-engineered [011]-poled relaxor-ferroelectric (1–x)Pb(Zn1/3Nb2/3)O3 – xPbTiO3 single crystal (x = 0.0475–0.09) and heterogeneous layers being systems of aligned piezoelectric Li2B4O7 single crystal rods in polyethylene, and these rods have an elliptic cylindrical shape. New diagrams show the volume-fraction ranges wherein large values of dh*> 10−9 C/N, dh*gh*> 2.10−10 Pa−1 and kh*≈ 0.5–0.6 are observed. [ABSTRACT FROM AUTHOR]

Through the current work, the usefulness of the concept of architectured rod lattices based on unit cell motifs designed at mesoscale is demonstrated. Specifically, 2D triangular lattices with unit cells containing different numbers of rods are considered. Combinations of rods of two different types provide the lattices explored with a greater complexity and versatility. For mesocells with a large number of variable parameters, it is virtually impossible to calculate the entire set of the points mapping the material onto its property space, as the volume of calculations would be gigantic. The number of possible motifs increases exponentially with the number of rods. Herein, the lattice metamaterials with mesoscale motifs are investigated with the focus on their elastic properties by combining machine learning techniques (specifically, Bayesian optimization) with finite element computations. The proposed approach made it possible to construct property charts illustrating the evolution of the boundary of the elastic compliance tensor of lattice metamaterials with an increase in the number of rods of the mesocell when a full‐factor experiment would not be possible. [ABSTRACT FROM AUTHOR]

Seismic anisotropy in the Earth's lower mantle likely results from a combination of elastic anisotropy and lattice preferred orientations of its main constituent minerals. As the second most abundant component of the lower mantle, ferropericlase has been widely studied, and the experimental results demonstrated, in general, a growing with pressure elastic anisotropy up to 1 Mbar. However, the unique measurements on the endmember (MgO) at comparable pressure conditions contradict the above observations and theoretical results. Here, time‐domain Brillouin scattering was applied to measure longitudinal sound velocities in single crystals of MgO compressed in diamond anvil cell. Velocities along two specific crystallographic directions, [100] and [111], were independently collected to 43 GPa. Applying the known bulk modulus, a complete set of single‐crystal elastic moduli, elastic anisotropy and aggregate shear modulus were derived. Our results revealed a steadily increasing with pressure elastic anisotropy at P > 20 GPa, consistent with the previous theoretical predictions and measurements on ferropericlase with moderate amounts of iron. Plain Language Summary: Variations in seismic wave velocities in the Earth's deep mantle can be explained, at least partially, by preferred orientations (caused by the mantle convection) combined with elastic anisotropy of one of the main constituents of the lower mantle, namely ferropericlase, (Mg1‐x,Fex)O. However, experimental and theoretical information on pressure dependence of its elastic anisotropy deviates from that measured for the end‐member MgO even though the predictions for MgO agree with those for (Mg1‐x,Fex)O. This is because measurement of elastic response of single crystals to uniaxial stress, for example, single‐crystal elastic moduli (Cij) and, accordingly, of elastic anisotropy at ultrahigh pressures is still challenging. Here, we measured Cij of MgO to the same degree of compression as in the upper part of the Earth's lower mantle using the advanced all‐optical technique adapted to diamond anvil cell which permits generation of ultrahigh pressures. We recorded an inversion of the elastic anisotropy of MgO upon compression and determined pressure dependence of its aggregate shear modulus. These results agree with the previously published data on ferropericlase. The influence of iron content on the elastic properties of (Mg1‐x,Fex)O at high pressures was discussed. Key Points: Sound velocities along specific directions in MgO single crystals were measured to 43 GPa using time‐domain Brillouin scatteringUpon compression, the Zener anisotropy ratio of MgO decreases steadily from above unity to below unityThe aggregate shear moduli of MgO and (Mg1‐x,Fex)O increase with pressure similarly but that of (Mg1‐x,Fex)O is smaller [ABSTRACT FROM AUTHOR]

On rock samples taken from the Cenomanian horizon of the PK1 formation of the gas and gas condensate fields of the Arctic shelf of Russia, direct physical modeling of the formation under the action of equal component stresses of breakouts in wells directed along the normal and along the occurrence was carried out. In the first case, the shape of the breakouts was cylindrical, and in the second case, in the form of two caverns. Such a form of breakouts, when interpreting well logging, is usually assumed to be caused by an unequal component stress field, which obviously does not correspond to the results of the experiments. Independent experiments were also carried out to determine the anisotropy of the elastic and strength properties of the studied rock. It was found that the studied rock has a specific type of strength anisotropy, not directly related to the weakening along the bedding. It is shown that this type of strength anisotropy can lead to the formation of breakouts of the observed shape. The main purpose of the article is to draw attention to the fact that stress anisotropy is not necessarily the main or only cause of the observed breakouts in wells. The results can be used in the design and development of hydrocarbon fields and underground gas storages, as well as in the interpretation of well measurements to determine the natural stress field in the Earth's crust. [ABSTRACT FROM AUTHOR]

We used Monte Carlo simulations with an elastically anisotropic pairwise potential to simulate the equilibrium structure of chiral and achiral nematic liquid crystals in spherical confinement under perpendicular and tangential strong anchoring. The stable structures are obtained by a quenching process, where the temperature is a parameter of the system. We calculate and map the distribution of elastic energy corresponding to splay, twist, and bend. Furthermore, we study the effect of changing the ratio of the elastic constants for achiral and low chirality droplets and found a diverse scenario of possible structures. The method described here allows the introduction of temperature and elastic anisotropy naturally within its framework. It is simpler to implement and faster to execute than the Landau-de Gennes (LdG) method used for simulating liquid crystal droplets. [ABSTRACT FROM AUTHOR]

Multi-stage hydraulic fracturing (MsHF) is the main technology to improve hydrocarbon recovery from shale plays. Associated with their rich organic contents and laminated depositional environments, shales exhibit transverse isotropic (TI) characteristics. In several cases, the lamination planes are horizontal in shale formations with a symmetric axis that are vertical to the bedding plane; hence, shale formations are known as transverse isotropic vertical (TIV) rocks. Ignoring the TIV nature of shale formations leads to erroneous estimates of in situ stresses and consequently to inefficient designs of fractural geometry, which negatively affects the ultimate recovery. The goal of this study is to investigate the effects of TIV medium characteristics on fractural geometry, spacing, and stress shadow development in the Jurassic Tuwaiq Mountain formation (TMF) in the Jafurah basin, which is a potential unconventional world-class play. This formation is the main source for prolific Jurassic oil reservoirs in Saudi Arabia. On the basis of a petrophysical evaluation in the Jafurah basin, TMF exhibited exceptional unconventional gas characteristics, such as high total organic content (TOC) and low clay content, and it was in the proper maturity window for oil and gas generation. The unconventional Jafurah field covers a large area that is comparable to the size of the Eagle Ford shale play in South Texas, and it is planned for development through multi-stage hydraulic fracturing technology. In this study, analytical modeling was performed to estimate the fractural geometry and in situ stresses in the anisotropic medium. The results show that the Young's modulus anisotropy had a noticeable impact on fractural width, whereas the impact of Poisson's ratio was minimal. Moreover, we investigated the impact of stress anisotropy and other rock properties on the stress shadow, and found that a large stress anisotropy could result in fractures being positioned close to one another or theoretically without minimal fractural spacing concerns. Additionally, we estimated the fractural aspect ratio in different propagation regimes and observed that the highest aspect ratio had occurred in the fractural toughness-dominated regime. This study also compares the elastic properties and confirms that TMF exhibited greater anisotropic properties than those of Eagle Ford. These findings have practical implications for field operations, particularly with regard to the fractural geometry and proppant placement. [ABSTRACT FROM AUTHOR]

Fractured hydrate-bearing reservoirs show significantly anisotropic geophysical properties. The joint application of seismic and electromagnetic explorations is expected to accurately assess hydrate resources in the fractured reservoirs. However, the anisotropic joint elastic-electrical properties in such reservoirs that are the key to the successful application of the joint explorations, remain poorly understood. To obtain such knowledge, we designed and implemented dedicated laboratory experiments to study the anisotropic joint elastic-electrical properties in fractured artificial silica sandstones (with fracture density of about 6.2%, porosity of approximately 25.7%, and mean grainsize of 0.089 mm) with evolving methane hydrate. The experimental results showed that the anisotropic compressional wave velocities respectively increased and decreased with the forming and dissociating hydrate, and the variation in the increasing trend and the decreasing extent of the velocity perpendicular to the fractures were more significant than that parallel to the fractures, respectively. The experimental results also showed that the overall decreasing trend of the electrical conductivity parallel to the fractures was steeper than that perpendicular to the fractures during hydrate formation, and the general variations of the two conductivities with complex trend were similar during hydrate dissociation. The variations in the elastic and electrical anisotropic parameters with forming and dissociating hydrate were also found to be distinct. Interpretation of the experimental results suggested that the hydrate binding to the grains evolved to bridge the surfaces of fractures when saturation exceeded 10% during hydrate formation, and the bridging hydrate gradually evolved to floating in fractures during dissociation. The experimental results further showed that the anisotropic velocities and electrical conductivities were correlated with approximately consistent trends of different slopes during hydrate formation, and the joint elasticelectrical anisotropic parameters exhibited a sharp peak at the hydrate saturation of about 10%. The results suggested that the anisotropic joint properties can be employed not only to accurately estimate hydrate saturation but also possibly to identify hydrate distribution in the fractures. [ABSTRACT FROM AUTHOR]

This work deals with non-linear d h k l − sin 2 ψ distributions, often observed in X-ray residual stress analysis of plastically deformed metals. Two different alloys were examined: duplex stainless steel EN 1.4362 with an austenite:ferrite volume ratio of 50:50 and ferritic stainless steel EN 1.4016. By means of an in situ experiment with high-energy synchrotron X-ray diffraction, the phase-specific lattice strain response under increasing tensile deformation was analysed continuously with a sampling rate of 0.5 Hz. From Debye–Scherrer rings of nine different lattice planes {hkl}, the d h k l − sin 2 ψ distributions were evaluated and the phase-specific stresses were calculated. For almost all lattice planes investigated, oscillating courses in the d h k l − sin 2 ψ distributions were observed, already occurring below the macro yield point and increasing in amplitude within the elasto-plastic region. By comparing the loaded and the unloaded state after deformation, the contribution of crystallographic texture and plastically induced intergranular strains to these oscillations could be separated. For the given material states, only a minor influence of crystallographic texture was observed. However, a strong dependence of the non-linearities on the respective lattice plane was found. In such cases, a stress evaluation according to the sin 2 ψ method leads to errors, which increase significantly if only a limited ψ range is considered. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate changes in the anisotropic elastic properties of ex vivo human cornea treated with ultraviolet cross-linking (CXL) using noncontact acoustic micro-tapping optical coherence elastography (AμT-OCE). Design: Acoustic micro-tapping OCE was performed on normal and CXL human donor cornea in an ex vivo laboratory study. Subjects: Normal human donor cornea (n = 22) divided into 4 subgroups. All samples were stored in optisol. Methods: Elastic properties (in-plane Young’s, E, and out-of-plane, G, shear modulus) of normal and ultraviolet CXL–treated human corneas were quantified using noncontact AμT-OCE. A nearly incompressible transverse isotropic model was used to reconstruct moduli from AμT-OCE data. Independently, cornea elastic moduli were also measured with destructive mechanical tests (tensile extensometry and shear rheometry). Main Outcome Measures: Corneal elastic moduli (in-plane Young’s modulus, E, in-plane, μ, and out-of-plane, G, shear moduli) can be evaluated in both normal and CXL treated tissues, as well as monitored during the CXL procedure using noncontact AμT-OCE. Results: Cross-linking induced a significant increase in both in-plane and out-of-plane elastic moduli in human cornea. The statistical mean in the paired study (presurgery and postsurgery, n = 7) of the in-plane Young’s modulus, E=3μ, increased from 19 MPa to 43 MPa, while the out-of-plane shear modulus, G, increased from 188 kPa to 673 kPa. Mechanical tests in a separate subgroup support CXL-induced cornea moduli changes and generally agree with noncontact AμT-OCE measurements. Conclusions: The human cornea is a highly anisotropic material where in-plane mechanical properties are very different from those out-of-plane. Noncontact AμT-OCE can measure changes in the anisotropic elastic properties in human cornea as a result of ultraviolet CXL. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references.

Porous silicon nitride is a promising material for many advanced applications due to its many outstanding properties. In this work, porous silicon nitride was fabricated at 1200 °C using a mixture of silicon nitride powder and phosphoric acid. The dual role of phosphoric acid as inorganic binder and pore former has been critically analyzed through a detailed structural characterization. Elastic constants of the porous silicon nitride samples were determined using non-destructive ultrasound phase spectroscopy, and the influence of the phosphoric acid content on the elastic properties was studied at depth. Both longitudinal and shear elastic constants were determined and Young's modulus and Poisson's ratio were calculated as a function of porosity considering the actual elastic symmetry of the fabricated samples. The experimentally determined elastic constants were compared with the predictions from different analytical models to understand the influence of porosity and pore morphology on the stiffness of the fabricated samples. [ABSTRACT FROM AUTHOR]

Although considerable efforts have been made in the last years to examine the physical properties of hexagonal close‐packed (hcp) iron at extreme conditions, it remains challenging to explain many geophysical observations in Earth's inner core. Here we examine the elastic and plastic behavior of hcp iron and the effects of structural defects at inner core conditions using large‐scale atomistic simulations coupled with machine learning‐based interatomic potential. Our results suggest that the seismic anisotropy pattern in the inner core can be ascribed to the elastic anisotropy (6%) of hcp iron. The observed low shear wave velocity is largely produced by viscous grain boundaries in iron polycrystal. We also found highly mobile and abundant vacancies in hcp iron yield a viscous strength (1015±1) that is consistent with the geophysical observations. Therefore, our findings highlight the role played by structural defects and lessen the demand for light elements to explain the observed seismic data. Plain Language Summary: Earth's inner core is mainly made of hexagonal close‐packed (hcp) iron. Seismic waves produced in an earthquake can explore its structure and dynamics. To interpret these seismic observations, we must understand the elastic and plastic properties of hcp iron at Earth's inner core conditions. Although considerable efforts have been made in the last years to examine hcp iron at extreme conditions, it remains challenging to explain many geophysical observations. Here we employed large‐scale molecular dynamics simulations based on the state‐of‐the‐art deep‐learning interatomic potential to investigate the physical properties of hcp iron and the effects of structural defects. Our results show that hcp iron is anisotropic enough to be compatible with the seismic anisotropy pattern in the inner core. The observed low shear wave velocity might be explained by the effects of viscous grain boundaries in polycrystalline iron. We also found that the low viscous strength of Earth's inner core is caused by highly mobile and abundant vacancies in hcp iron. Therefore, our results highlight the role played by structural defects and lessen the demand for light elements to explain the observed seismic data. Key Points: Elastic anisotropy of hexagonal close‐packed (hcp) iron is about 6% at inner core conditionsThe observed low shear wave velocity is consistent with viscous grain boundaries in iron polycrystalThe low viscosity of the inner core is caused by highly mobile and abundant vacancies in hcp iron [ABSTRACT FROM AUTHOR]

Purpose: Development of a quantitative model and associated workflow for predicting the mechanical deformation properties (plastic deformation or cleavage fracture) of organic single crystals from their crystallographic structures using molecular and crystallographic modelling. Methods: Intermolecular synthons, hydrogen bonding, crystal morphology and surface chemistry are modelled using empirical force fields with the data integrated into the analysis of lattice deformation as computed using a statistical approach. Results: The approach developed comprises three main components. Firstly, the identification of the likely direction of deformation based on lattice unit cell geometry; secondly, the identification of likely lattice planes for deformation through the calculation of the strength and stereochemistry of interplanar intermolecular interactions, surface plane rugosity and surface energy; thirdly, identification of potential crystal planes for cleavage fracture by assessing intermolecular bonding anisotropy. Pentaerythritol is predicted to fracture by brittle cleavage on the {001} lattice planes by strong in-plane hydrogen-bond interactions in the <110>, whereas pentaerythritol tetranitrate is predicted to deform by plastic deformation through the slip system {110} < 001>, with both predictions being in excellent agreement with known experimental data. Conclusion: A crystallographic framework and associated workflow for predicting the mechanical deformation of molecular crystals is developed through quantitative assessment of lattice energetics, crystal surface chemistry and crystal defects. The potential for the de novo prediction of the mechanical deformation of pharmaceutical materials using this approach is highlighted for its potential importance in the design of formulated drug products process as needed for manufacture by direct compression. [ABSTRACT FROM AUTHOR]

A physical simulation of the formation of wellbore wall breakouts was carried out on rock samples with holes drilled perpendicular to the bedding. The simulation demonstrated the appearance of pronounced oriented breakouts under uniform lateral stresses. Some hypotheses are proposed to explain the observed phenomena. According to the first hypothesis, it is assumed that the reason lies in the combined effect of anisotropy of strength and anisotropy of elasticity of a certain type, determined by a parameter different from the ratio of the elastic moduli along and normal to the layering. According to the second hypothesis, the reason may be the suppression of the growth of secondary breakouts after the initiation of the primary breakout. According to the third hypothesis, the reason can be associated solely with the strength anisotropy of a certain type. The results are useful in the design and development of hydrocarbon fields and underground gas storages and in the interpretation of well data to determine the stress state in the Earth's crust. [ABSTRACT FROM AUTHOR]

Sn-based solders are known for their tendency to form coarse grained microstructures. In combination with the high elastic anisotropy of β -Sn, the overall elastic properties and their interpretation require a careful discussion of the structure–property-relationship as elastic constants are often important input parameters for creep or fatigue models. This study therefore investigates the influence of microstructure and testing method on the Young's modulus E for the widespread lead free solder alloy Sn-Ag3.8-Cu0.7 (SAC387) using bulk specimens. Due to its already high homologous temperature at room temperature (T hom ≈ 0.6 = T/T m for T m being the melting temperature), hot tensile tests generally bear the risk of superimposed creep deformation. Mechanical testing becomes even more challenging, since yield strengths are usually low for these alloys. Consequently, in addition to the hot tensile tests executed for the engineering strain rate ϵ ̇ e = 1 ⋅ 1 0 − 3 s−1, two supplemental methods are used to determine the Young's modulus comprising of the dynamic resonance frequency measurement and the calculation of the Young's modulus based on single crystal compliance data of the majority phase β -Sn.Young's moduli yielded from dynamic resonance frequency measurement and calculations based on single crystal compliance data showed comparable results of (E 35 °C ≈ 55 GPa, E 80 °C ≈ 51 GPa and E 125 °C ≈ 48 GPa). Hot tensile tests showed similar data with the largest deviation at 80 °C, where E 80 °C ≈ 53 GPa was determined. These absolute values and their temperature dependence can be attributed to the microstructure of the cast specimens which show a general preferred orientation of β -Sn grains close to < 110 > after analysis via electron backscattered diffraction (EBSD). A comparison with literature data revealed significant differences in the Young's moduli which are likely to be attributed to differences in the preferred orientation of β -Sn grains. • Three different methods of Young's modulus determination yielded comparable results. • A strong influence of β -Sn orientation on the elastic behavior was found. • Distinct differences in literature regarding the Young's modulus of lead free solders is likely related to β -Sn anisotropic elastic properties. [ABSTRACT FROM AUTHOR]

Titanium and its alloys combine an important mechanical anisotropy and a high capacity to dissolve oxygen. The detailed evolution of the elastic compliance of titanium as a function of its oxygen content is only partially known, despite its importance in structural applications. Here, high speed nanoindentation mapping (HSNM) was conducted on a grade 2 commercially pure titanium (CP-Ti) to probe elastic and hardness anisotropy as well as property evolution as a function of the oxygen content within Ti using pre-oxidized specimens. The oxygen concentration investigated ranged from 600 ppm to 20% atomic. Pre-oxidation of the CP-Ti was performed at 700 °C for 100 h under air to create a gradient of oxygen content within the metal, denoted oxygen-rich layer (ORL). Local oxygen content was quantified using microprobe analyses (EPMA) and crystal orientation using electron backscattered diffraction (EBSD). Reduced modulus and hardness maps were obtained on the pre-oxidized sample within the ORL and far from the ORL using large but highly resolved nanoindentation technique in continuous stiffness measurement (CSM) mode. Data merging techniques were used on this multi-modal dataset to statistically link local mechanical properties to chemical and crystal orientation information. Oxygen insertion in the Ti lattice was found to significantly increase the hardness and elastic moduli of titanium and was correlated to orientation of the c -axis of the α-Ti as a function of the nanoindentation loading direction. Using the Vlassak and Nix theory, it was possible to identify the evolution of the C ij terms of the stiffness matrix as a function of the oxygen content up to 20% at. in O. [Display omitted] • Large high-speed nanoindentation mapping aimed at assessing both reduced modulus and hardness properties at the sub-grain level. • EBSD and EPMA analyses were performed to have local information on the grain orientation and local oxygen content. • A Python companion was developed and shared on Zenodo for high-throughput mechanical characterization using multimodal data merging. • The evolution of the elastic anisotropy and hardness properties of titanium enriched with oxygen up to 20% at. was characterized. • The Vlassak and Nix theory was implemented to identify the C ij terms of the stiffness tensor for the Ti-O system using a transversely isotropic elastic model. [ABSTRACT FROM AUTHOR]

In this study, we investigate the composition-dependent mechanical properties and elastic anisotropies of sII hydrogen hydrates using first-principles method. The evaluation of the elastic moduli and their direction dependency is achieved by computing the second-order elastic constants (SOECs) of the unit lattice. The various trends of elastic constants with the hydrogen composition of the cages introduces variations in the bonding strength, compressibility, stiffness, and shear properties of the structure which are captured by the Poisson's ratio, bulk, Young, and shear moduli, respectively. Elastic properties were found to be significantly influenced by the system's anisotropy, arising from the geometry of the cages and their unique arrangement within the lattice being affected by the increase in the hydrogen occupancy of the cages. The detailed analysis of elastic anisotropies revealed shifts in the strongest and weakest directions of the material with varying the hydrogen content of the cages. The Poisson's ratio captures the anisotropic bonding strengths within the crystal structure with the hydrogen composition of the lattice, explaining the reason behind the existence of strongest and weakest directions in terms of compression, tension, and shear forces. Taken together the established structure-property-composition relations will be useful in the design and optimization of hydrogen sII hydrates for energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigated the mechanical stability, elastic anisotropy, electronic and piezoelectric properties of ZrSiO₃ 2D monolayer subjected to varying degrees of strain. The monolayer films were characterized under strains ranging from −6% to +6 %, and different material properties were analyzed to understand their response to mechanical deformation using density functional theory with the Quantum Espresso code. The calculated values of cohesive and strain energy revealed that the material exhibited a symmetrical response to tension and compression within a strain value range of −2% to +2 %. Electronic properties showed strain-induced modifications: the band gap of the material decreases under tensile strain and increases under compressive strain. The material remained mechanically stable and ductile under the applied strain range of −6% to +6 %. Present investigations conveyed the modifications produced by strain on elastic anisotropy and piezoelectric characteristics of the material, finding their applications in strain-sensitive sensors, actuators, and energy-harvesting devices. • Investigation of mechanical, electronic, and piezoelectric properties under varying degrees of strain (−6% to +6 %). • Strain-induced modifications in electronic structure, with the band gap increasing under tensile strain and decreasing under compressive strain. • Mechanical stability and ductility maintained under strains ranging from −6% to +6 %. • Elastic anisotropy and piezoelectricity suggest potential for ZrSiO3 in strain sensors, actuators, and energy-harvesting devices. [ABSTRACT FROM AUTHOR]

• A constitutive model of an elastic body with a triclinic lattice structure is derived. • Elasticity tensors depending on crossing angles between members are examined. • Diverse dependence of elastic properties on crossing angles is investigated. • The size effect of the torsional property and how to cancel it out are explored. • Effects of geometrical shapes of the members on the torsional property are revealed. Triclinic lattice structures with generalized parallelepiped unit cells are crucial targets in understanding the influence of lattice structure on the mechanical behaviors of lattice elastic bodies. This study models a three-dimensional elastic body with a triclinic lattice microstructure comprising three uniform elastic members rigidly joined at a single point. Based on the linear couple stress theory, a specialized case of the Cosserat theory, this study derives elasticity tensors in the constitutive equations of the triclinic lattice elastic body that depend on the crossing angles between the members. To derive the angular-dependent elasticity tensors, coordinate transformations between oblique and orthogonal coordinate systems are effectively employed in formulating the substitution of deformation and force fields in the continuum for the fields in the lattice structure. Evaluating the elasticity tensors reveals the influences of the crossing angles on the anisotropic tensile and torsional properties, the existence of the angle-covariant lattice number manipulation that cancels out the size effect, and several types of geometrical shape dependence. This study could contribute to the theoretical evaluation of elastic behaviors of both artificially engineered and naturally formed materials with lattice microstructures. [ABSTRACT FROM AUTHOR]

The structural, magnetic, and electronic features of Cr 2 InN are investigated using PBE and PBE+U approaches. The computed formation enthalpy and formation energy values indicate that the aforementioned compound could be synthesized experimentally. Cr 2 InN exhibits metallic characteristics as there is no bandgap visible at the Fermi level. The spin polarization calculation in bulk without on-site coulomb interaction reveals a very minute energy difference between ferromagnetic (FM) and antiferromagnetic (AF) ground states, while for U = 1 eV, the results confirm the AF ground state. However, in the supercell calculation, in-plane antiferromagnetic1 (in-AFM1) is more stable than in-AFM2 and FM configurations for the U parameters 0 eV and 1 eV. The inclusion of spin orbit coupling with and without the correlation effect does not have a significant impact on the magnetic properties of Cr 2 InN. The computed elastic constants C i j reveal the mechanical stability of Cr 2 InN. The Voigt–Reuss–Hill approximation is successfully utilized for calculating the Young modulus, shear modulus, and bulk modulus. The Pugh's and Poisson's ratios show that Cr 2 InN is ductile. The anisotropic nature of Cr 2 InN is observed from 2D and 3D plots of elastic moduli and anisotropic indices. The phonon spectra of the present system predict that Cr 2 InN is dynamically stable, as it does not display imaginary frequencies. In addition, the thermal and thermodynamic properties of Cr 2 InN have been calculated, including its melting temperature, minimum thermal conductivity, Debye temperature, entropy, specific heat capacity, free energy, and internal energy. Cr 2 InN might be useful for thermal barrier coatings because it has low values for Young's modulus, minimum thermal conductivity, and lattice thermal conductivity. We hope these theoretical findings offer valuable insights for future experimental research on Cr 2 InN. [ABSTRACT FROM AUTHOR]

Severe plastic deformation of commercially pure titanium, leading to ultrafine-grained microstructure, can be used as an alternative to alloying to obtain better mechanical properties without the reduction of biocompatibility and corrosion resistance. However, the strong texture, induced by plastic deformation, results in anisotropy of mechanical properties, understanding of which is crucial to design and model perspective structural parts and devices. In this work, ultrafine-grained grade 2 Ti, obtained by equal channel angular pressing, is investigated. A detailed study of the texture and the elastic anisotropy of the material, heat-treated at several annealing temperatures, is conducted, complemented by ex-situ and indirect in-situ thermal experiments, which shed light on the stability and evolution of microstructure and material properties. The results show that the elastic properties only slightly evolve during annealing in contrast to other properties, such as thermal expansion, internal friction or hardness. The elastic anisotropy is directly linked to the (0001) texture, thus outlining the importance and possibilities of texture-based design and tailoring of mechanical properties.

Abstract The radial jet drilling (RJD) technology is typically developed to open multiple lateral micro‐holes from a main wellbore to the formation. The multiple groups of 3D numerical models of radial micro‐holes through a main well are built by incorporating the pore hydro‐mechanical coupling effects. A number of sensitivity analyses were conducted on the effects of the radial jetting azimuth, the stress anisotropy, and the elastic anisotropy on the rock fracture initiation of the micro‐holes. As revealed from the results, the fracture initiation from the micro‐hole exhibited the diversified characteristics with the increase in the jetting azimuth of the micro‐hole. On the whole, the fracture initiation point was concentrated at the maximum principal stress. Thus, the jetting azimuth of the nozzle was recommended to be designed in the interval of 0°‐30°. A higher elastic modulus anisotropy ratio K and a lower Poisson's ratio anisotropy ratio K′ caused the significant rigidity characteristics of the rock, which increased the possibility of fracture initiation in the horizontal direction; a lower elastic modulus anisotropy ratio K and a higher Poisson's ratio anisotropy ratio K′ caused the strong rigidity characteristics, so the rock could not easily fracture in the vertical direction. Several suggestions were given that the rock is easy to be broken by selecting a smaller jetting azimuth angle and a more significant in‐situ stress difference. The numerical simulation results agree well with field experiment results, with an average accuracy of 97.17%. The proposed numerical model has a good performance in predicting the fracture initiation pressure of the radial micro‐hole in anisotropy formation.

We use Landau–de Gennes theory to investigate the configurations of liquid crystals confined to a submicron spherical droplet subject to weak homeotropic anchoring. The results show that in a one-constant approximation, there are three equilibrium configurations: radial hedgehog, ring disclination and uniform, where the radial hedgehog configuration is a stable state. With increasing elastic anisotropy, which is essentially an increase in the splay elastic constant, the radial hedgehog configuration transforms into a split-core configuration, which is metastable. The split-core configuration becomes the lowest-energy state induced by saddle-splay elasticity within appropriate ranges of the radius and elastic anisotropy. [ABSTRACT FROM AUTHOR]

Quantitative estimates of reservoir parameters and elastic anisotropy using seismic methods is essential for characterizing shale oil reservoirs. Rock physics models were established to quantify elastic anisotropy associated with clay properties, laminated microstructures, and bedding fractures at different scales in shale. The inversion schemes based on the built rock physics models were proposed to estimate reservoir parameters and elastic anisotropy using well log data. Based on the back propagation neural network framework, the obtained rock physical inversion results were used to establish the nonlinear models between elastic properties and reservoir parameters and elastic anisotropy of shale. The established correlations were applied for quantitative seismic interpretation, converting seismic inversion results to the reservoir parameters and elastic anisotropy to characterize the shale oil reservoir comprehensively. The predicted elastic anisotropy of the shale matrix reflects the lamination degree and the mechanical properties of the shale, which is critical for the effective implementation of hydraulic fracturing. The calculated elastic anisotropy of the shale provides more accurate models for seismic modeling and inversion. The obtained bedding fracture parameters provide insights into reservoir permeability. Therefore, the proposed method provides valuable information for identifying favorable oil zones in the study area. [ABSTRACT FROM AUTHOR]

First-principles calculations were used to estimate the anisotropic elastic and thermal properties of Ti2lnX (X = C, N) and Zr2lnX (X = C, N) M2AX phases. The crystals' elastic properties were computed using the Voigt-Reuss-Hill approximation. Firstly, the material's elastic anisotropy was explored, and its mechanical stability was assessed. According to the findings, Ti2lnC, Ti2lnN, Zr2lnC, and Zr2lnN are all brittle materials. Secondly, the elasticity of Ti2lnX (X = C, N) and Zr2lnX (X = C, N) M2AX phase are anisotropic, and the elasticity of Ti2lnX (X = C, N) and Zr2lnX (X = C, N) systems are different; the order of anisotropy is Ti2lnN > Ti2lnC, Zr2lnN > Zr2lnC. Finally, the elastic constants and moduli were used to determine the Debye temperature and sound velocity. Ti2lnC has the maximum Debye temperature and sound velocity, and Zr2lnN had the lowest Debye temperature and sound velocity. At the same time, Ti2lnC had the highest thermal conductivity. [ABSTRACT FROM AUTHOR]

Nanoindentation is a promising tool for advancing the estimation of single crystal elastic constants in multiphase materials. In this study, a novel protocol is presented that couples high-speed nanoindentation mapping with the Vlassak and Nix's model and Bayesian inference simulations to statistically estimate the elastic constants of cubic materials. The originality lies in considering ratios of indentation modulus as input data. For cubic elasticity, these ratios depend solely on two dimensionless parameters, which can be chosen as the Zener ratio A and the directional Poisson's ratio ν 〈 100 〉 . Using ratios mitigates the influence of experimental calibration parameters. Only two constants are varied in the Bayesian simulations, and the computation time is further reduced by employing an optimized Vlassak and Nix's model. This approach has also the great advantage to bound the search domain of ν 〈 100 〉 and A directly from elastic stability conditions. Furthermore, the method efficiency allows for continuous variation of the uncertainty considered in the experimental moduli, leading to stabilized Bayesian inference results. The choice of the finally retained values is thus simplified, converging to the uniqueness of the single crystal elastic constants. This method is successfully applied to high-purity Ni and Inconel 718, with the predicted elastic constants aligning well with literature data. [Display omitted] [ABSTRACT FROM AUTHOR]

In this article, a detailed study of the recently synthesized MAX phase borides M2SB (M = Zr, Hf and Nb) has been performed via first principles technique. Investigation of mechanical properties, elastic anisotropy, optical properties, dynamical stability and thermal properties are considered for the first time. The estimated values of stiffness constants and elastic moduli are found in good agreement with available results. The Vickers hardness is also calculated using Mulliken population analysis. The electronic density of states and charge density mapping are used to explain the variation of stiffness constants, elastic moduli and hardness parameters among the studied ternary borides. The Nb2SB compound is found to show the best combination of mechanical properties. Mixture of covalent and ionic bonding within these borides is explained using Mulliken population analysis. The direction dependent values of Young's modulus, compressibility, shear modulus and Poisson's ratio are visualized by 2D and 3D representations and different anisotropic factors are calculated. The important optical constants are calculated and analyzed. The metallic nature of the studied borides is confirmed from the density of states (DOS) and optical properties. The reflectivity spectra reveal the potential use of Zr2SB as coating materials to diminish solar heating. The studied borides are dynamically stable as confirmed from the phonon dispersion curves. The characteristic thermodynamic properties have also been calculated and analyzed. The physical properties of corresponding 211 MAX phase carbides are also calculated for comparison with those of the titled ternary borides.