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Low-temperature, low-pressure Cu-to-Cu direct bonding technology is a promising solution for next-generation high-density interconnects. Previous studies have shown that many properties of nanomaterials are determined by their structural characteristics. Therefore, the effect of the nanostructure (i.e., twin crystal and twin boundary, TB, sizes) on the bonding mechanism and mechanical response of the direct bonding of (111)-oriented nanotwinned Cu (NT-Cu) is studied using molecular dynamics simulations, where TB size means the TB layer thickness in terms of the number of atoms. The simulation results show that NT-Cu with extremely small twin crystals (e.g., 0.625 nm) have poor diffusivity. The number of dislocations induced by plastic deformation increases with increasing twin crystal size during stretching processes, degrading mechanical strength. The strain hardening of bonded NT-Cu with extremely small twin crystals (e.g., 0.625 nm) is dominated by the strong barrier created by a high density of TBs, whereas that with twin crystal sizes of 2.5–10 nm is dominated by dislocation–TB and dislocation–grain boundary interactions. Bonded NT-Cu with 2–6 atoms per TB layer exhibits softening at initial plastic deformation due to the onset of partial collapse of TBs; however, the strength then significantly increases with a further increase in strain due to strain hardening. [ABSTRACT FROM AUTHOR]

Applying graphene (Gr) coatings to high-entropy alloys (HEA) is anticipated to enhance their tribological characteristics. The current understanding of the mechanism by which the Gr/HEA is enhanced at the atomic level is still limited. Molecular dynamics simulations revealed the mechanical behavior and strengthening mechanism of the Gr/AlCoCrFeNi HEA during nanoindentation and nanoscratch. The results demonstrate a substantial increase in the indentation hardness of the Gr/AlCoCrFeNi HEA by about 2.4 times. When Gr changed from a single layer to three layers, it further improved (3.2 times for a double layer and 3.9 times for three layers). At the same time, the friction coefficient is effectively reduced. Furthermore, the elevated in-plane stiffness of the Gr coating leads to an expansion of the effective loading area, resulting in increased Shockley dislocation and stair-rod dislocation density within the Gr/AlCoCrFeNi HEA, thereby amplifying the strain hardening effect and reducing subsurface damage. Qualitative experiments confirmed the excellent wear resistance of the Gr/HEA, and coating Gr increased the width of scratches, effectively confirming our simulation results. These findings provide valuable insights for the development and design of Gr/HEA composite coatings with enhanced mechanical properties. [ABSTRACT FROM AUTHOR]

We simulate an alloy of HfNbTaTi mixed in six different proportions and also of the equiatomic system under uniaxial tensile loading at 300 K. Molecular dynamics simulation trajectories are analyzed using radial distribution functions, OVITO, bond-orientational order parameters, and coordination numbers. Equiatomic and the two other alloys (Hf 0.31 Nb 0.23 Ta 0.23 Ti 0.23 and Hf 0.23 Nb 0.31 Ta 0.23 Ti 0.23 ) containing comparable fraction of elements deform similarly through the formation of an amorphous state. Two alloys rich in Nb (Hf 0.17 Nb 0.50 Ta 0.16 Ti 0.17 ) and Ta (Hf 0.17 Nb 0.16 Ta 0.50 Ti 0.17 ) deform similarly resulting in the formation of bcc atoms, which transform to fcc at higher loading. Finally, alloys rich in Hf (Hf 0.50 Nb 0.16 Ta 0.17 Ti 0.17 ) and Ti (Hf 0.17 Nb 0.16 Ta 0.17 Ti 0.50 ) deform resulting in high dislocation densities and hcp atoms. These two hcp-rich alloys also undergo strain hardening. In each mixture during loading, local orientational order of all the different elements changes similarly. Atoms prefer to pair with other atoms than to themselves during tensile loading. [ABSTRACT FROM AUTHOR]

Hydra has a tubular bilayered epithelial body column with a dome-shaped head on one end and a foot on the other. Hydra lacks a permanent mouth: its head epithelium is sealed. Upon neuronal activation, a mouth opens at the apex of the head which can exceed the body column diameter in seconds, allowing Hydra to ingest prey larger than itself. While the kinematics of mouth opening are well characterized, the underlying mechanism is unknown. We show that Hydra mouth opening is generated by independent local contractions that require tissue-level coordination. We model the head epithelium as an active viscoelastic nonlinear spring network. The model reproduces the size, timescale and symmetry of mouth opening. It shows that radial contractions, travelling inwards from the outer boundary of the head, pull the mouth open. Nonlinear elasticity makes mouth opening larger and faster, contrary to expectations. The model correctly predicts changes in mouth shape in response to external forces. By generating innervated : nerve-free chimera in experiments and simulations, we show that nearest-neighbour mechanical signalling suffices to coordinate mouth opening. Hydra mouth opening shows that in the absence of long-range chemical or neuronal signals, short-range mechanical coupling is sufficient to produce long-range order in tissue deformations.

Mg–Zn–Al matrix composites reinforced with bimodal-size SiC p (average size of ∼8 μm and ∼60 nm) are fabricated by semi solid stirring casting process and extrusion process. The influence of bimodal size SiC p on microstructure and texture evolution, mechanical properties as well as work hardening behavior of Mg–Zn–Al matrix composites are investigated. The results reveal that the area fraction of unrecrystallization (unDRX) region decreases from 12.8 % of matrix alloy to 5.2 % of 9 wt% m-SiC+1 wt% n-SiC/Mg–6Zn–3Al-0.5Ca(M9N1) composite, and the average grain size (AGS) is reduced sharply with addition of SiC p , which decreases from 7.3 μm of matrix alloy to 0.9 μm of M9N1 composite. The addition of micron SiC p (m -SiC p) promotes the generation of nano precipitates, and the precipitate size is reduced further after the addition of nano SiC p (n-SiC p). The intensity of basal texture decreases firstly and then increases with the addition of m- and n-SiC p because of the pinning effect from n-SiC p and nano precipitates for grain boundary. The bimodal-size SiC p particles have been observed to significantly enhance the strength of the composite. The M9N1 composite demonstrates exceptional performance, and its yield strength and ultimate tensile strength is 322 MPa and 360 MPa, respectively. The exceptional strength of the composite can be attributed to various strengthening mechanisms, including grain refinement, precipitate strengthening, dislocation strengthening, and the load transfer effect. [ABSTRACT FROM AUTHOR]

Concrete is used worldwide as a construction material in many projects. It exhibits a brittle nature, and fibers' addition to it improves its mechanical properties. Polypropylene (PP) fibers stand out as widely employed fibers in concrete. However, conventional micro-PP fibers pose challenges due to their smooth texture, affecting bonding within concrete and their propensity to clump during mixing due to their thin and soft nature. Addressing these concerns, a novel type of PP fiber is proposed by gluing thin fibers jointly and incorporating surface indentations to enhance mechanical anchorage. This study investigates the incorporation of macro-PP fibers into high-strength concrete, examining its fresh and mechanical properties. Three different concrete strengths 40 MPa, 45 MPa, and 50 MPa, were studied with fiber content of 0–1.5% v/f. ASTM specifications were utilized to test the fresh and mechanical properties, while the RILEM specifications were adopted to test the bond of bar reinforcements in concrete. Test results indicate a decrease in workability, increased air content, and no substantial shift in fresh concrete density. Hardened concrete tests, adding macro-PP fibers, show a significant increase in splitting tensile strength, bond strength, and flexural strength with a maximum increase of 34.5%, 35%, and 100%, respectively. Concrete exhibits strain-hardening behavior with 1% and 1.5% fiber content, and the flexural toughness increases remarkably from 2.2 to 47.1. Thus, macro PP fibers can effectively improve concrete's mechanical properties and resistance against crack initiation and spread. [ABSTRACT FROM AUTHOR]

AISI 301LN metastable austenitic stainless steels (MASSs) are known to exhibit high work‐hardening rates attributed to martensite evolution during straining which results in the second‐phase strengthening mechanism. This enhances surface hardness and potentially reduces wear and rolling contact fatigue (RCF). The aim of this study is therefore to evaluate the work hardening, wear, and RCF performance of AISI 301LN metastable austenitic stainless steel as a possible alternative material for rolling and sliding applications by varying the contact conditions such as slip ratio against the standard R350HT rail steel using a twin‐disc simulator. The results show that 301LN MASS has high surface work hardening and increased hardness because of martensitic transformation, while R350HT rail steel has only slightly changed. The formation of a hard martensitic phase is also confirmed by X‐ray diffraction analysis as well as by two other techniques, indicating a secondary hardening effect. Although it shows potential for work hardening, its susceptibility to wear‐related problems may make it less suitable for rolling and sliding applications due to a cracking and spalling mechanism induced by martensite formation. The surface strains required for the observed martensite formation are calculated and found to be very high, approaching 0.4. [ABSTRACT FROM AUTHOR]

In this study, tungsten–copper (W–Cu) composite was fabricated using the sintering process to examine the corrosion, wear and hardness of the fabricated samples at three different temperatures of 1050, 1150 and 1300 °C. The potentiodynamic polarization behavior of the composite samples was evaluated in 3.5% NaCl solution containing different benzotriazole inhibitors. Finally, the microstructure of the W–Cu composite was examined by SEM, TEM, XRD and EDS analyses. The XRD results on the milled samples showed that the optimal conditions were obtained with a ball to powder ratio of 16:1 and a milling time of 15 h, so that the crystals with a size of 16.76 nm were obtained. Also, the highest hardness (185 HV) and relative density (97.34%) were obtained in the samples sintered at 1300 °C. With increasing the wear force, the work hardening increased in the mechanically mixed layer, which led to a rise in the wear rate and a decrease in the friction coefficient. The corrosion behavior of the composite indicated that by addition of 200 ppm inhibitor in the corrosion solution, the corrosion current density decreased from 3.73 to 0.59 μA/cm2 and the corrosion potential improved from − 630.46 to − 336.28 mVSCE. [ABSTRACT FROM AUTHOR]

The running-in period during dry sliding wear might determine the evolution to steady-state wear behaviour. To this end, the running-in period during sliding wear of austenitic stainless steel, AISI 316L stainless steel, and Hadfield steel were studied through the testing pin (flat-ended)-on-disk configuration. The effects of the normal load, sliding speed, and alloy type were assessed, and the specific wear rate and strain hardening characteristics were determined. The wear rate was correlated with wear mechanism, friction coefficient, hardening, and roughness to characterize the changes occurring during the running-in period. These changes could influence the responses of these materials to wear during the steady-state period. The stabilization of the specific wear rate and hardness was noted to align with the end of the running-in period. [ABSTRACT FROM AUTHOR]

During thermo-mechanical processing, dissolved alloying elements have a huge impact on the microstructure evolution by influencing the overall dislocation storage rate. Especially, for non-heat treatable Al alloys, the effects of strain-hardening and solid solution strengthening are of significant practical interest. In the present work, a detailed study of the room temperature work-hardening behavior of binary Al–Cu, Al–Zn, and Al–Mn alloys with varying solute concentrations is carried out. Stress–strain curves at different strain rates are recorded and computationally analyzed by an advanced 3-Internal-Variables-Model (3IVM) approach for the dislocation density evolution. The initial strengthening rate is examined as a function of the solute concentration. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive and innovative approach to tailoring the microstructure of AISI 9254 steel using a quenching and partitioning (Q&P) process, demonstrating significant improvements in mechanical and wear properties. The initial pearlitic microstructure was first heated to the fully austenitizing region before undergoing phase transformation into a multi-phase matrix using the novel Q&P process, resulting in the formation of ferrite, bainite, martensite, and retained austenite. Investigation revealed the central role of retained austenite in enhancing the mechanical properties through the Transformation Induced Plasticity (TRIP) effect. In particular, heat-treated specimens exhibited a mechanical resistance of up to 1.9 GPa and an elongation of approximately 12 pct. Furthermore, this study highlights remarkable enhancements in wear resistance of the treated AISI 9254 steel. A decreased wear rate, reduced volume loss, and improved contact area stability were achieved, attributed to debris aggregation, contact area changes, and the work hardening of the wear track. Consequently, the Q&P process can considerably enhance the in-service performance and life span of AISI 9254 steel components. The insights provided by this work into the potential benefits of a tailored Q&P process in AISI 9254 steel set forth a promising pathway towards reduced maintenance costs and heightened reliability across various applications. Exploring this process showcases the transformative potential of materials engineering for industrial applications. [ABSTRACT FROM AUTHOR]

Tailor weld blank (TWB) is preferred in different components of automobiles to reduce weight of the vehicle. However, TWBs have lower formability than sheets because of increased hardness and strength of weld region. Hence, in this work, detailed formability analysis of TWB of AISI304 is done and compared with as-received sheets along with microstructural correlation. Forming limit diagram for as-received sheet, TWBs are determined. Strain hardening exponent value of as-received sheet is 0.381, unweld region and weld region of TWB is observed to be 0.362 and 0.301, respectively. Numerical simulations were also done for predicting the FLC of TWB of AISI304 with the help of PAM STAMP 2 G solver. TWB showed lower formability than as-received sheets. Similarly, predicted FLD for TWB is almost coinciding with the experimental value. Similarly, optical micro-structure studies were also analysed for as-received sheet, unweld region and weld region of TWB, which showed fully austenitic structure with random grain orientations. At the same time, it was found that strain path chosen for FLD determination has a strong influence on microstructure evolution. [ABSTRACT FROM AUTHOR]

In this investigation, Cu-TiO2-Graphite hybrid composites were fabricated with variations in wt.% of TiO2 and fixed wt.% of Graphite contents through stir casting technique. The size of the grains measured after casting were 83 ± 04, 64 ± 10, 41 ± 10 and 29 ± 04 μm for 0, 3, 6, and 9 wt% hybrid composites, respectively. The addition of 1 wt.% graphite (Gr) was not only to enhance the mechanical and tribological properties but also to improve the wettability during casting. The influence of TiO2 and Gr in Cu-hybrid composite on compression test was investigated followed by characterisation studies involving XRD, EDS, TEM, EBSD. The results reveal that 9 wt% reinforced composite exhibits more strain hardening. Further, composite exhibits higher strength due to the presence of combined strengthening mechanisms such as grain boundary, Orowan and thermal expansion coefficient mismatch in commensurate with ceramic particle addition. Out of these, it is found that Orowan strengthening contributes significantly to the compression strength of the hybrid system investigated. [ABSTRACT FROM AUTHOR]

The author aimed to enhance the functional characteristics of the proposed Ti–Ni shape memory alloy (SMA) with a functionally graded property by ultrasonic shot peening (USP) treatment. To the author’s knowledge, this was the first study in which USP treatment was utilized for manufacturing functionally graded SMAs; previous studies relied on powder metallurgy and hot rolling techniques. By examining the various properties of the specimens, the author confirmed the effects of hot rolling and USP treatment. Hot rolling and USP treatment led to an increased Vickers hardness. Hot rolling primarily contributed to densification, while USP treatment induced work hardening, resulting in increased hardness. The surface of TiNi SMA sintered bodies experienced compressive residual stress up to 300 MPa because of the USP treatment. The transformation peaks in differential scanning calorimetry curves shifted toward lower temperatures as the Ni content increased. Therefore, the transformation properties of the functionally graded shape memory alloys were unaffected by the USP treatment. The USP treatment work-hardens the sintered TiNi SMA produced through hot rolling. The effect was more pronounced in the high-Ni-concentration region, resulting in the development of a functionally graded behavior of deformation resistance. [ABSTRACT FROM AUTHOR]

AbstractThe strain hardening behavior of friction stir welded AA7039 (Al-4.2Zn-3.1 Mg) alloy was explored in terms of dislocation density, crystallite size, hardening capacity, hardening exponent, and strain hardening rate. Strain hardening behavior was analyzed for base metal and friction stir welded specimens. Four different models were used to calculate the dislocation density viz., Scherrer model, uniform strain model (USM), uniform stress distribution model (USDM), and uniform strain energy distribution model (USDEM). Maximum dislocation density was obtained in base metal for all models (maximum for USM, 3.9 ×1015m−2) with a minimum crystallite size of 15.81 nm. The low dislocation density in FSW samples is due to the higher heat input in the FSW process. Strain hardening stages were shown by Kocks–Mecking type plots. Lower strain hardening capacity was obtained for BM, i.e. 0.427 as compared to FSW samples, due to the higher dislocation density of BM. It was determined that there is an inverse relationship between the strain hardening capacity and the strain hardening exponent. Strain hardening rate was higher for BM than FSW specimens, and similar results were obtained from mathematical relations that indicate the adequacy of the results. The ultimate tensile strength was 2.5% higher than the BM at a rotational speed of 1325 rpm, 35 mm/min of welding speed and 1.65° tilt angle. The maximum strength friction stir-welded specimen showed a more ductile fracture surface than the BM because the grain boundary phase disappeared or broke up in the thermomechanical affected zone. [ABSTRACT FROM AUTHOR]

Adhesives can be made by patterning surfaces with discrete adhesive elements. Nature uses this approach to provide animals with highly adaptive and robust approaches towards gaining an effective grip on surfaces. The mechanism of patterned surface adhesion involve many different attachment principles, adhesive site interactions, and probabilistic effects, the interplay of which is not understood. This limits our ability to design patterned surface adhesives for engineering applications. In this work, we quantify how a mechanically patterned adhesive based on passive mushroom-shaped elements performs. We explore a range of surface design features and model the mechanical adhesion dynamics with an approach based on the fiber bundle model (FBM). We find that the fiber bundle model can be used to rationalize the observations after modifying it to capture the initial non-linear force response of the adhesives. Additionally, we investigate the behavior of the system's elastic energy and damage energy, as it is stretched under strain-controlled conditions. Our experimental data indicates that the elastic energy has a maximum that appears after the macroscopic strength (σc), corresponding to strains where a full rupture of the system can no longer be prevented. Moreover, we observed that below the maximum of the constitutive curve σc, the elastic energy consistently exceeds the damage energy. Finally, we found that the derivative of the elastic energy has a maximum, which always appears before σc. Therefore, the derivative of the elastic energy would serve as a reliable signal of upcoming catastrophic failure in experiments under stress-controlled conditions. [ABSTRACT FROM AUTHOR]

Over the past few decades, titanium (Ti) alloys containing fully or mostly body-centred cubic β phase in metastable state have received considerable interest due to their elevated strength with remarkable ductility. Apart from dislocation slip, the plastic deformation of metastable β Ti alloys involves either twinning-induced plasticity (TWIP), transformation-induced plasticity (TRIP), or the complex coupling of both (TWIP/TRIP). The pursuance of better mechanical performance necessitates the fundamental understanding of these various deformation mechanisms and has driven substantial studies. Therefore, the present work reviews recent research on the mechanical behaviour of TWIP and/or TRIP metastable β Ti alloys, with special emphasis on the role of different plasticity modes in enhancing work hardening. The effective inhibition to dislocation slip produced by deformation-induced twins and phases which gives rise to the dynamic Hall–Petch effect is discussed in detail since it underpins the TWIP/TRIP engineering. In particular, the correlation between deformation twinning and stress-induced phase transformation is well addressed. It is expected that such review may shed light on the underlying physics of the intricate deformation behaviour of metastable β Ti alloys and inspire more studies in designing novel Ti alloys with superior mechanical properties. [ABSTRACT FROM AUTHOR]

Heterostructured (HS) materials, characterized by heterogeneous zones with differences in mechanical or physical properties, represent a revolutionary advancement in material science. During deformation, hetero‐deformation‐induced (HDI) stress forms due to the synergistic interactions between soft and hard zones, leading to remarkable HDI strengthening and strain hardening. This mechanism significantly enhances their performance, surpassing that of traditional homogeneous materials. This review delves into the classification, preparation techniques, fundamental deformation mechanisms, and research methods of HS materials. It outlines the preparation methods of various HS materials, emphasizing their unique characteristics and applications. The review elaborates on the fundamental deformation mechanisms of HS materials, focusing on non‐uniform plastic deformation behavior and HDI strain hardening. Furthermore, it explores the application of heterogeneous design concepts in materials, analyzing their microstructure tuning mechanisms and mechanical properties. This review aims to serve as a critical reference for the future design and development of new HS metallic structural materials, paving the way for innovations that can transform multiple industries. By highlighting the long‐term impact, this review not only enhances the understanding of HS materials but also provides a roadmap for future research and industrial applications, positioning HS materials as key players in the advancement of material technology. [ABSTRACT FROM AUTHOR]

Compared to the traditional alloys, high entropy alloys exhibit exceptional strength and outstanding ductility, making them highly attractive for use in demanding engineering applications. However, the atomic-scale deformation behavior of HEAs with precipitate under the low-cycle loading conditions has not been well studied. Here, we utilize molecular dynamics simulations to investigate the low cycle fatigue behavior of AlCoCrFeNi HEAs with AlNi-rich phase, in order to better understand the cyclic deformation, work hardening, and damage mechanisms. In the stress-strain hysteresis loops, the stress in the elastic stage exhibits a gradual linear increase, followed by fluctuations at yielding and plastic deformation. The strain hardening depends on the cycle number after the yielding stage. With an increase in the number of cycles, the activation mode of stacking faults gradually transitions from a multi-slip system to a single-slip system, attributed to the gradual phase transformation. A thorough examination of dislocation evolution is crucial in understanding the strengthening and plastic behavior of materials under cyclic loading. The generation of more stair-rod dislocations further suppresses the movement of dislocations. The combined effects of element diffusion, structural transformation, and incoherent precipitation play a critical role in enhancing the mechanical properties of AlCoCrFeNi HEAs. The strength of high entropy alloys is improved through interface strengthening caused by element diffusion and structural transformation, along with dispersion induced by incoherent precipitation. This work provides a detailed atomic-level understanding of the cyclic deformation-induced strengthening mechanism, in order to design highstrength and ductile HEAs with specific desired properties. [ABSTRACT FROM AUTHOR]

In the field of ultrasonic-assisted micro-forming, in addition to acoustic softening, impact effects also play a significant role, especially in terms of influencing the deformation behavior of surfaces, such as by generating more deformation on surface asperity. In this study, to understand the mechanisms involved in the effect of an impact, ultrasonic-assisted micro-forging tests were conducted on commercially pure copper, pure aluminum, and pure titanium. A method that can measure the increment in the temperature during ultrasonic vibration was developed. As a result, changes in the surface temperature of the material under the impact effect and acoustic softening were measured. It is indicated that, during ultrasonic vibration, the heat generated through acoustic softening is very limited and the main heat increase occurs after the impact effect. Once the impact effect occurs, the surface temperature increases with increasing amplitude. Nevertheless, for materials with different crystal structures, the influences of the impact effect are also different. The surfaces of copper and aluminum soften, creating more surface deformation, but the exact opposite effect is seen on a titanium surface. Observing the evolution of the microstructure on the material surface with EBSD demonstrates that the impact effect on FCC materials can reach deeper below the surface in terms of temperature diffusion compared to titanium. Meanwhile, the impact effect in the case of titanium causes the regeneration of twinning, which is reduced under the influence of the acoustic softening effect, consequently resulting in strain hardening. [ABSTRACT FROM AUTHOR]

Mg–8Al–1Zn magnesium alloy was successfully processed using deferential speed rolling (DSR) at temperatures of 400 and 450 °C for thickness reduction of 30, 50, and 70% with no significant grain growth and dynamic recrystallization. Using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), the rolled microstructures were examined. Although the results indicate a slight reduction in grain size from the initial condition, the DSR processing of alloy at an elevated temperature was associated with a significant number of twins and a distribution of the fine particles of the second phase. The strength in terms of microhardness measurements and strain hardening in terms of shear punch testing was significantly improved in the rolled microstructure at room temperature. The existence of twins and widely distributed second-phase fine particles at twin boundaries reflected positively on the extent of the elongations in terms of shear displacements when microstructures were tested at elevated temperatures in the shear punch testing. [ABSTRACT FROM AUTHOR]

Before artificial ageing, extruded aluminium profiles are subjected to stretching with a small cold deformation in the range of 0.5–2%. This deformation improves the geometrical stability of the extruded product and causes changes in the microstructure of the profile, which leads to the strain hardening of the material after artificial ageing. The work has resulted in the creation of the prototype of an original device, which is unique in the world, for the dynamic stretching of the extruded profiles after quenching. The semi-industrial unit is equipped with a hydraulic system for stretching and a pneumatic system for cold dynamic deformation. The aim of this research paper is to produce advantageous microstructural changes and increase the strength properties of the extruded material. The solution of the dynamic stretching of the profiles after extrusion is a great challenge and an innovation not yet practised. The paper presents the results of microstructural and mechanical investigations carried out on extruded AlMgSi(Cu) alloys quenched on the run-out table of the press, dynamically stretched under different conditions, and artificially aged for T5 temper. Different stretching conditions were applied: a static deformation of 0.5% at a speed of 0.02 m/s, and dynamic deformation of 0.25%, 0.5%, 1%, and 1.5% at speeds of 0.05 and 2 m/s. After the thermomechanical treatment of the profiles, microstructural observations were carried out using an optical microscope (OM) and a scanning electron microscope (SEM). A tensile test was also carried out on the specimens stretched under different conditions. In all the cases, the dynamically stretched profiles showed higher strength properties, especially those deformed at a higher speed of 2 m/s, where the increase in UTS was observed in the range of 7–18% compared to the classical (static) stretching. The microstructure of the dynamically stretched profiles is more homogeneous with a high proportion of fine dispersoids. [ABSTRACT FROM AUTHOR]

This study uses a sigmoidal function to describe the plastic strain hardening of metallic materials, considering temperature and strain rate effects. The effectiveness of this approach is evaluated and systematically compared with other hardening laws. Incorporating temperature and strain rate effects into the parameters of this sigmoidal-type hardening law enables a more precise description and prediction of the plastic deformation of materials under different combinations of temperature and strain rate. The temperature effect is coupled using a simplified Arrhenius model, and the strain rate effect is coupled with a modified Johnson–Cook model. The sigmoidal-type hardening law is integrated with an asymmetric yield criterion to address complex behavior, such as anisotropy and strength differential effects. The calibration and validation of the constitutive model involve examining uniaxial tensile/compressive flow curves in various directions and biaxial tensile/compressive flow curves for diverse metallic alloys, proving the proposed model's broad applicability. [ABSTRACT FROM AUTHOR]

This study compares the tensile properties of single-phase and dual-phase polycrystalline FeNiAl alloys using molecular dynamics (MD) simulation. The findings reveal that dual-phase polycrystalline materials, incorporating both B2-NiAl and face-centered cubic (FCC)-Fe phases, exhibit significantly superior strength and strain hardening compared to their single-phase FCC-FeNiAl counterparts. The back stress and Bauschinger effect emerge as pivotal factors in strengthening and strain hardening during the tensile deformation of dual-phase polycrystalline materials. In single-phase polycrystalline materials, grain plastic deformation is uniform, primarily driven by Shockley partial dislocation b = 1 6 < 121 > . Additionally, deformation twinning is observed with increasing strain. Conversely, in dual-phase polycrystalline materials, non-uniform plastic deformation occurs because of differences in crystal structure between the two phases. Plastic deformation predominantly takes place in the soft domain FCC-Fe grains, while dislocations encounter hindrance from the hard domain B2-NiAl grains, leading to the generation of back stress. The direction of dislocation movement opposes the back stress, further impeding plastic deformation and enhancing material strength. In cases where the back stress is sufficiently high, the dislocation source may halt dislocation emission, creating significant stress concentration between soft and hard domains, consequently causing local stress and strain and ultimately leading to crack formation. The comprehension of these mechanisms provides a valuable reference for developing FeNiAl alloys with exceptional mechanical properties. [ABSTRACT FROM AUTHOR]

The work hardening behavior of dual-phase Mg–8Li–3Al–1Nd alloy sheet is investigated at 293–473 K with a strain rate of 0.083–0.00083 s−1. Experiment results show that the flow stress is sensitive to deformation conditions, and decreased with the increased of temperature and the reduced of strain rate. On the basis of flow stress curves, the work hardening behavior is analyzed as work hardening rate (θ) with net flow stress (σ-σy) and true strain (εp) curves, which is defined as four stages: stage II (linear hardening stage), stage III and IV (softening stage), stage V (late deformation stage), but the work hardening stage II only occurs under certain conditions. The stage II, III and IV can be expressed by three models. By the models, the work hardening rate can be predicated. [ABSTRACT FROM AUTHOR]

The rheological properties of a polyamide (PA) resin with low crystallinity were modified by melt-mixing it with a small amount of an alternative α-olefin–maleic anhydride copolymer as a reactive compound. Because PA has a low melting point, rheological characterization was performed over a wide temperature range. Owing to the reaction between PA and the alternative α-olefin–maleic anhydride copolymer, the blend sample behaved as a long-chain branched polymer in the molten state. The thermo-rheological complexity was obvious owing to large flow activation energy values in the low modulus region, i.e., the rheological time–temperature superposition principle was not applicable. The primary normal stress difference under steady shear was greatly increased in the wide shear rate range, leading to a large swell ratio at the capillary extrusion. Furthermore, strain hardening in the transient elongational viscosity, which is responsible for favorable processability, was clear. Because this is a simple modification method, it will be widely employed to modify the rheological properties of various polyamide resins. [ABSTRACT FROM AUTHOR]

The wear and corrosion resistance of 316L austenitic stainless steel after strain hardening were studied. 316L austenitic stainless steel was composed of a large amount of austenite and a small fraction of martensite. After strain hardening at room temperature, the contents of phases were not changed basically. With the increase of pre-strain deformation, the microhardness of the surface and cross-section slightly increased, and the microhardness of the sample with pre-strain deformation of 20% was the largest. When the pre-strain deformation was greater than 5%, the surface microhardness was greater than the cross-sectional microhardness. The dynamic average friction coefficients of the stainless steel after pre-strain deformation of 0%, 5%, 10%, and 20% were 0.67, 0.57, 0.2, and 0.12, respectively. The friction coefficient of the samples gradually decreased with the increase of strain hardening. The wear resistance of 316L stainless steel was improved after pre-strain deformation. The steel with pre-strain deformation of 20% had a small abrasive scratch depth and low friction coefficient, which exhibited good wear resistance. The corrosion resistance of the samples after strain hardening deteriorated for the initial state without immersion due to the existence of defects. The corrosion resistance of the sample with pre-strain deformation of 5% after soaking for 3 days was the best, compared with the other as-strained samples. [ABSTRACT FROM AUTHOR]

The present study introduces a novel method of high-density pulsed electric current (HDPEC) as a substitute for the conventional annealing heat treatment process to relieve strain hardening in 6061 aluminum alloy (A6061) during the manufacturing process. The study investigates the effects of different HDPEC treatments on the strain-hardening relief of cold-rolled A6061, with a comparison to the traditional annealing heat treatment. The results reveal that the HDPEC-treated samples demonstrate a remarkable reduction of approximately 50% in strength and a considerable increase of approximately 200% in ductility, indicating complete strain-hardening relief of cold-rolled A6061. Consequently, the HDPEC treatment is faster and more efficient than the traditional annealing heat treatment. Furthermore, the HDPEC-treated samples display equivalent mechanical properties as the untreated ones after the final precipitation heat treatment, indicating that the HDPEC treatment has no detrimental effect on the materials. The microstructural characterization demonstrates that the HDPEC-induced microstructural modification through dislocation elimination and grain recovery leads to the strain-hardening relief of cold-rolled A6061. These findings suggest that the HDPEC treatment can even replace the hot-forming process of A6061, contributing to low-cost and high-efficient manufacturing. [ABSTRACT FROM AUTHOR]

The microstructure evolution of stress-induced martensite (SIM) α ″ and mechanical twins in metastable β Ti-1023 alloy under different strains during tensile and compressive deformation was investigated by the help of X-ray diffraction, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. The results demonstrate that there is no obvious SIM α ″ stress platform in the compressive stress–strain curve; however, it exhibits a higher yield stress and strain hardening capability than tensile deformation although SIM α ″ and α ″ martensite twinning are the major deformation products that appeared in metastable β Ti-1023 alloy under both tensile and compressive loading. In fact, SIM α ″ is preferentially activated in well-oriented β grains at the beginning of deformation, and those activated variants have the largest phase transformation strain along the loading direction affected by the loading stress state. As the accumulated deformation strain increases, SIM α ″ is reoriented to form a martensite co-deformation region with twin structures through {111}α″ type I and <211>α″ type II twinning systems. Then, the primary lath α ″ martensite is consumed, resulting in the development of the {130} <310>α″ and {110} < 110 > α ″ deformation twinning inside the martensite. In comparison with tensile deformation, compressive deformation produces a higher volume fraction of SIM α ″ and α ″ martensite twins in β grains, along with a higher density of dislocations in the α ″ martensite and the coordinated deformation region of the martensite. This results in a higher work hardening ability of the alloy under compression and a marked asymmetry of mechanical characteristics compared to tensile deformation. [ABSTRACT FROM AUTHOR]

Materials often fail prematurely or catastrophically under load while containing voids, posing a challenge to materials manufacturing. We found that a metal (gold) containing spherical voids with a fraction of up to 10% does not fracture prematurely in tension when the voids are shrunk the submicron or nanometer scale. Instead, the dispersed nanovoids increase the strength and ductility of the material while simultaneously reducing its weight. Apart from the suppressed stress or strain concentration, such structure provides enormous surface area and promotes surface-dislocation interactions, which enable strengthening and additional strain hardening and thus toughening. Transforming voids from crack-like detrimental defects into a beneficial “ingredient” provides an inexpensive and environmentally friendly approach for the development of a new class of lightweight, high-performance materials. [ABSTRACT FROM AUTHOR]

The tempering process is applied in marine 10Ni5CrMoV steel to study microstructure, and mechanical properties by multi‐scale characterizations, strain hardening behavior, and cryogenic toughening mechanism are further investigated. As the tempering temperature increases from 590 to 630 °C, the dislocation density decreases by up to 25% and the austenite volume fraction decreases by up to 35%. Additionally, the morphology of austenite changes from strip to bulk, which weakened the pinning effect on the laths, leading to a coarsened martensite and an increase in the equivalent grain size. Based on the modified Crussard–Jaoul analysis, the specimens at different tempering temperatures exhibit a single‐stage strain hardening behavior during plastic deformation. The increase in strength is attributed to the continuous transformation‐induced plasticity effect and the increasing dislocation density. Furthermore, high austenite volume fraction and the proportion of grain boundary misorientation above 45° promote the release of stress concentration and hinder the propagation of cracks. This results in an increase in the ductile–brittle transition temperature (DBTT) of the specimens from −105 to −135 °C. At a tempering temperature of 610 °C, the specimen demonstrates an outstanding balance between yield strength (868 MPa) and cryogenic toughness (DBTT of −135 °C). [ABSTRACT FROM AUTHOR]

Intermetallic alloys have traditionally been characterized by their inherent brittleness due to their lack of sufficient slip systems and absence of strain hardening. However, here we developed a single-phase B2 high-entropy intermetallic alloy that is both strong and plastic. Unlike conventional intermetallics, this high-entropy alloy features a highly distorted crystalline lattice with complex chemical order, leading to multiple slip systems and high flow stress. In addition, the alloy exhibits a dynamic hardening mechanism triggered by dislocation gliding that preserves its strength across a wide range of temperatures. As a result, this high-entropy intermetallic circumvents precipitous thermal softening, with extensive plastic flows even at high homologous temperatures, outperforming a variety of both body-centered cubic and B2 alloys. These findings reveal a promising direction for the development of intermetallic alloys with broad engineering applications. Intermetallics are traditionally characterised by their inherent brittleness due to a lack of sufficient slip systems and the absence of strain hardening. Here authors show that a single-phase distorted high entropy B2 intermetallic alloy displays notable strength and plasticity at room temperature, along with stable plastic flow at high homologous temperatures. [ABSTRACT FROM AUTHOR]

The correlation between the single-point notched constant tensile load-stress crack resistance (SP-NCTL SCR) Test (ASTM D5397; Appendix) of smooth high density polyethylene (HDPE) geomembranes and their strain hardening modulus is investigated for both unaged and aged specimens. The strain hardening modulus was calculated based on the (force-elongation) raw data from the tensile strength test conducted at room temperature using Type IV and/or Type V specimens (as described in ASTM D638) at a test speed of 7 mm/min. Three different approaches are used to define the strain hardening modulus and to compare the representative strain hardening modulus with the SP-NCTL SCR. It is shown that the high test speed of 7 mm/min performed at room temperature provides a good correlation with the SP-NCTL SCR of different smooth black HDPE geomembranes. Additionally, the proposed method using Type V specimens predicts the SCR values during oxidative degradation close to those observed using the SP-NCTL SCR test. For the resins and conditions examined, the proposed method provides a quick assessment of the SP-NCTL SCR of unaged geomembranes when the SP-NCTL SCR takes long testing times (e.g., >1000 h) or in jurisdictions in which the use of surfactants becomes prohibited to allow conducting the SP-NCTL SCR tests. • Presents a correlation between the NCTL-SCR of HDPE GMBs and strain hardening slope at room temperature at 7 mm/min. • Presents a correlation with a transformed post-yield load-elongation curve for unaged specimens using Type V and IV specimens. • Presents a correlation with a transformed post-yield load-elongation curve for aged and unaged specimens using Type V specimens. • Shows that the strain hardening test conducted at room temperature at 7 mm/min can predict the SCR with the same level of accuracy as the NCTL tests. [ABSTRACT FROM AUTHOR]

This study investigates the quasi-static and dynamic compressive mechanical properties of polyamide-6 at different temperatures (25–85 ℃) and strain rates (2.6 × 10−4–3.2 × 103 s−1) by using a universal testing machine and a split Hopkinson pressure bar device. The variation of mechanical properties with temperature and strain rate is analyzed. The results show that the stress–strain response of polyamide-6 at different temperatures and strain rates includes viscoelastic deformation, yield behavior, and strain hardening behavior. Under some experimental conditions, polyamide-6 has constant stress flow states, which are related to temperature and strain rate. The mechanical properties of polyamide-6 are significantly affected by temperature and strain rate. The elastic modulus, yield strength, and energy absorption property increase with an increase of strain rate, but decrease with an increase of temperature. The formulas of yield strength and elastic modulus are given, and a modified constitutive model is given to describe the stress–strain response of polyamide-6. The predicted results of the model are in good agreement with the experimental data at different temperatures and strain rates. [ABSTRACT FROM AUTHOR]

Antigorite occurs at seismogenic depth along plate boundary shear zones, particularly in subduction and oceanic transform settings, and has been suggested to control a low‐strength bulk rheology. To constrain dominant deformation mechanisms, we perform hydrothermal ring‐shear experiments on antigorite and antigorite‐quartz mixtures at temperatures between 20 and 500°C at 150 MPa effective normal stress. Pure antigorite is strain hardening, with frictional coefficient (μ) > 0.5, and developed cataclastic microstructures. In contrast, antigorite‐quartz mixtures (10% quartz) are strain weakening with μ decreasing with temperature from 0.36 at 200°C to 0.22 at 500°C. Antigorite‐quartz mixtures developed foliation similar to natural serpentinite shear zones. Although antigorite‐quartz reactions may form mechanically weak talc, we only find small, localized amounts of talc in our deformed samples, and room temperature friction is higher than expected for talc. Instead, we propose that the observed weakening at temperatures ≥200°C primarily results from silica dissolution leading to a lowered pore‐fluid pH that increases antigorite solubility and dissolution rate and thus the rate of dissolution‐precipitation creep. We suggest that under our experimental conditions, efficient dissolution‐precipitation creep coupled to grain boundary sliding results in a mechanically weak frictional‐viscous rheology. Antigorite with this rheology is much weaker than antigorite deforming frictionally, and strength is sensitive to effective normal stress and strain rate. The activation of dissolution‐precipitation in antigorite may allow steady or transient creep at low driving stress where antigorite solubility and dissolution rate are high relative to strain rate, for example, in faults juxtaposing serpentinite with quartz‐bearing rocks. Plain Language Summary: Some major, plate‐boundary fault zones are very weak, and in some places this is thought to be because they contain the mineral serpentine. Antigorite is a common form of serpentine at depth, but in many rock deformation experiments, antigorite is found to be relatively strong. In natural fault zones, however, antigorite can be highly deformed at seemingly low stress. The motivation for this study was to explore whether antigorite can be weak also in the laboratory. Because laboratory experiments occur relatively fast, the mechanism of deformation may be different from in nature. To address this, we mixed antigorite with quartz, which changes the pH and promotes dissolution of antigorite. We found that when deforming antigorite mixed with quartz, the experimental fault was very weak, because the dissolution of antigorite removed sticking points ‐ a process that is also documented in natural faults. The experiments also produced minor talc, from the reaction of antigorite with quartz, but too little to affect strength. We suggest that it is the activation of dissolution and precipitation of antigorite which allows deformation of major serpentine‐bearing faults at low stress at temperatures of several hundred degrees Celsius. Key Points: At 20°C and 500°C antigorite is strain‐hardening, develops cataclastic microstructures and has a frictional coefficient of ∼0.5Samples of antigorite mixed with quartz are strain‐weakening, and the friction coefficient decreases from 0.36 at 200°C to 0.22 at 500°CThe weakness of quartz‐antigorite is associated with activation of dissolution‐precipitation creep [ABSTRACT FROM AUTHOR]

The long chain branching (LCB) polyglycolide (PGA) was successfully prepared by the successive reactions of the terminal hydroxyl groups of PGA with triglycidyl isocyanurate (TGIC) and pyromellitic dianhydride (PMDA). The influence of LCB produced by functional group reaction on rheological and crystallization behavior was studied and discussed through linear rheology, uniaxial elongation and DSC (differential scanning calorimetry). The much higher viscosity and the more notable strain hardening behavior of modified PGA indicates the LCB with high degree of entanglements are created. The melt strength of PGA is finally improved greatly and can make sure that the supercritical CO2 foaming can be carried out successfully. [ABSTRACT FROM AUTHOR]

The effect of high-temperature deformation twinning on the work hardening behaviors of Fe-38Mn alloy during hot shear-compression deformation was investigated. The discovery of micro-shear bands and deformation twinning is significant for continuous work hardening, and this represents an important step toward gaining a complete understanding of the effect of deformation twinning on work hardening behaviors. Deformation twinning is widely acknowledged to accommodate plastic strain under cold deformation, even under severe plastic deformation. At present, the equivalent stress vs. strain curves for hot shear-compression deformation of Fe-38Mn alloy exhibit the characteristics of continuous work hardening. In addition, continuous work hardening is classified into five stages when considering high-temperature deformation twinning. [ABSTRACT FROM AUTHOR]

This work examines the void growth and coalescence in isotropic porous elastoplastic solids with sigmoidal material hardening via finite element three-dimensional unit cell calculations. The investigations are carried out for various combinations of stress triaxiality ratio (T ) and Lode parameter (L ) and consider a wide range of sigmoidal hardening behaviors with nominal hardening rates spanning two decades. The effect of L is considered in the presence and in the absence of imposed shear stress. Our findings reveal that depending on the nature of sigmoidal hardening the cell stress-strain responses may exhibit two distinct transitions with increasing stress triaxiality (T ). Below a certain lower threshold triaxiality the stress-strain responses are sigmoidal, while above a certain higher triaxiality they exhibit softening immediately following the yield. Between these threshold levels, the responses exhibit an apparent classical rather than sigmoidal strain hardening. The sigmoidal hardening characteristics also influence porosity evolution, which may stagnate before a runaway growth up to final failure. For a given L , an imposed shear stress adversely affects the material ductility at moderate T whereas at high T it improves the ductility. Finally, we discuss the role of material hardening and stress state on the residual cell ductility defined as strain to final failure beyond the onset of coalescence. [ABSTRACT FROM AUTHOR]

Sheet metals subjected to biaxial plane stress loading typically fail due to localized necking in the thickness direction. Classical plasticity models using a smooth yield surface and the normality flow rule cannot predict localized necking at realistic strain levels when both the in-plane principal strains are tensile. In this paper, a recently developed multi-surface model for porous metal plasticity is used to show that the development of vertices on the yield surface at finite strains due to microscopic void growth, and the resulting deviations from plastic flow normality, can result in realistic predictions for the limit strains under biaxial tensile loadings. The shapes of the forming limit curves predicted using an instability analysis are in qualitative agreement with experiments. The effect of constitutive features such as strain hardening and void nucleation on the predicted ductility are discussed. [ABSTRACT FROM AUTHOR]

In this paper, the cyclic elastic–plastic behaviors of the centrifugal steam compressor impeller (CSCI) structure under practical operating conditions are discussed employing the linear matching method (LMM). The three‐stage strategy of the LMM is employed to determine the shakedown and ratchet boundaries by conducting a series of iterative direct steady cyclic analysis, and based on this, the load regions corresponding to different types of damage behavior that may occur during the operation are identified. Computational results reveal slight contraction in the structural response diagram when considering actual material constitutive relationships, compared to ideal elastic–plastic models. Meanwhile, by integrating the unified ratchet and fatigue program with fatigue experimental data, a series of constant low‐cycle fatigue life curves has been presented for different service conditions. Furthermore, a comparison with detailed step‐by‐step inelastic analyses confirms the applicability and great efficiency of the LMM in practical engineering problems. Highlights: The cyclic elastic‐plastic behavior of impeller were investigated using the three‐stage procedure.The effect of temperature‐dependent and strain hardening on structural response of impeller were evaluated.The constant low‐cycle life fatigue curves of the impeller structure were generated.The applicability and great efficiency of linear matching method have been confirmed. [ABSTRACT FROM AUTHOR]

Unsaturated contaminated soil from domestic sources has a significant impact on engineering construction. Taking unsaturated CH3COOH contaminated clay as the research object, unsaturated triaxial tests under different matrix suction and different net confining pressure were carried out, and the strength parameters and strength prediction formula were obtained. The prediction results of unsaturated soil strength of Fredlund Xing soil water characteristic curve model and Van Genuchten soil water characteristic curve model were compared. Scanning electron microscopy (SEM) was used to observe and analyze the characteristics of the microstructure of contaminated clay. It shows that the matric suction of unsaturated soil can increase the cohesion and internal friction angle of unsaturated soil, and the increase is linear, which conforms to the bivariate shear strength relationship. As the suction of the matrix increases, the stress–strain curve gradually changes from strain softening to strain hardening. The prediction result of unsaturated soil strength based on Fredlund-Xing soil water characteristic curve model is better than that based on Van Genuchten soil water characteristic curve model, and the smaller the confining pressure and the greater the matrix suction, the more accurate the prediction result.CH3COOH dissolves minerals and hard iron compound minerals in the soil, reduces soil strength and increases soil deformation. [ABSTRACT FROM AUTHOR]

The hydraulic bulge test with micro-samples is expected to be useful in the damage assessment of long-service-period metals to understand the degeneration of their mechanical properties. Since the hydraulic bulge test has a different stress state from the classical uniaxial tensile test, we need to understand their correlation and differences. In this study, the hydraulic bulge test and the uniaxial tensile test are employed to analyze the mechanical properties of three typical metals used in pressure vessels: 316L, 16MnDR, and Q345R. By utilizing Kruglov's vertex thickness and Panknin's curvature radius equivalent, the pressure–displacement curves from the hydraulic bulge test are converted into biaxial stress–strain curves. Based on the equivalent plastic energy model, the biaxial stress–strain curves are converted into uniaxial stress–strain curves with an error less than 10% in the strain hardening stage, achieving the unified characterization of mechanical properties under different stress states. Moreover, the hydraulic bulge test provides a more extensive strain hardening stage, and the fracture strains are 9–16.5% larger than those of uniaxial tensile test. This paper provides a reference for using the hydraulic bulge test with micro-samples in studying the mechanical properties and presents the advantages of this novel test method. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) with hetero-grains exhibit high strength with good ductility. A trimodal grain structure composed of ultrafine grains (UFGs), fine grains (FGs) and coarse grains (CGs) prevents the pre-mature cracking of hetero-zone boundaries in conventional bimodal grain structures; thus, it is favored by AMCs. However, the design of the size and distribution of hetero-domains in trimodal AMCs is tough, with complicated multi-scale deformation mechanisms. This study tunes the distribution of FG domains elaborately via altering the volume fraction of FG from 10 vol.% to 60 vol.% and investigates the distribution effect of FG domains on strength–ductility synergy. The optimized 2024 Al matrix composites with 30 vol.% FG exhibited a tensile strength of over 700 MPa and an elongation of 7.5%, respectively, realizing a good combination of high strength and ductility. This work enlightens the heterostructure design with a balance between heterogeneous deformation induced (HDI) strain hardening and high-content soft phase induced strain homogenization. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel (ASS) and duplex stainless steel (DSS) are referred as "difficult-to-cut" materials in the manufacturing industry because of different machining difficulties including work hardening, high cutting temperatures and formation of built-up layers. DSS is the preferred replacement for ASS but includes a difficult manufacturing environment. Moreover, the wet machining conditions raise several issues related to the human health, environment, disposition and costing. However, turning of these materials in the dry environment is a challenging task. The present research work is a comparison of machinability aspects of ASS 304 and DSS 2205 in a dry environment using AlTiN coating deposited by two advanced coating deposition techniques including direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). Uncoated tools showed the worst performance at every stage of machining. AlTiN (HiPIMS)-coated tools showed the lowest increase in average surface roughness of 8%, 17% lower cutting force and 1.5-times higher tool life compared to AlTiN (DCMS) tools. DSS 2205 was the most difficult material to machine in dry conditions, exhibiting the lowest average tool life of 3890 mm compared to 4315 mm by ASS 304. Moreover, HiPIMS-coated tools helped in improving the machining performance of DSS 2205 up to some extent. [ABSTRACT FROM AUTHOR]

Zirconium alloy with the composition of 90.1% Zr and alloying elements such as Mg, Al, and Si was investigated for its mechanical properties and corrosion resistance. The specimen was dissolved in a mixture of NaOH, Na2CO3, S, and SnO2 at 800°C for 10 min, followed by an HCl solution at room temperature for 100 cycles. The structural properties were characterized by X-ray diffraction and scanning electron microscopy, while the mechanical properties, such as tensile strength were investigated by a universal tensile machine. The microstructural observations indicated that the outside part of the crucible underwent pitting corrosion which resulted in corrosion in all directions inside that part of the crucible. The corrosion structure consisted of cracks that reached the base metal. The residual chemical from the fusion and dissolution process remained in the crack and formed NaCl, which accelerated the crack. The release rate of the zirconia oxide layer was calculated to be 8 μm per cycle. During the corrosion process at high temperatures, oxygen diffusion infiltrated the base metal and stretched the crystal lattice, causing strain hardening with the values of yield strength and ultimate tensile strength increased to 22.5% while the strain decreased by 50%. [ABSTRACT FROM AUTHOR]

The viscoelastic response of carrageenan hydrogels to large amplitude oscillatory shear (LAOS) has not received much attention in the literature in spite of its relevance in industrial application. A set of hybrid carrageenans with differing chemical compositions are gelled in the presence of KCl or NaCl, and their nonlinear viscoelastic responses are systematically compared with mixtures of kappa- and iota-carrageenans of equivalent kappa-carrageenan contents. Two categories of LAOS response are identified: strain softening and strain hardening gels. Strain softening gels show LAOS non-reversibility: when entering the nonlinear viscoelastic regime, the shear storage modulus G′ decreases with increasing strain, and never recovers its linear value G0 after successive LAOS sweeps. In contrast to this, strain hardening carrageenan gels show a certain amount of LAOS reversibility: when entering the nonlinear regime, G′ increases with strain and shows a maximum at strain γH. For strains applied below γH, G0 shows good reversibility and the strain hardening behavior is maintained. For strains larger than γH, G0 decreases significantly indicating an irreversible structural change in the elastic network. Strain hardening and elastic recovery after LAOS prevail for hybrid carrageenan and iota-carrageenan gels, but are only achieved when blends are gelled in NaCl, suggesting a phase separated structure with a certain degree of co-aggregated interface for mixed gels. [ABSTRACT FROM AUTHOR]

The microbial induced partial saturation (MIPS) technique is the new environmentally friendly, cost-effective technique applicable under existing structures for mitigating sand liquefaction. The current study investigated the effectiveness of MIPS for mitigating sand liquefaction under undrained static loading. A series of undrained static triaxial tests were conducted to examine the influence of biogenic gas production through microbial denitrification on poorly graded sand at various relative densities. Initial batch experiments revealed that increased nitrate concentrations resulted in a decreased degree of saturation. Loosely and medium-dense saturated samples exhibited positive pore pressure during loading, which was reduced through biological desaturation, resulting in increased undrained shear strength ratios. Dense saturated and desaturated samples produced negative excess pore pressure, decreasing the undrained strength of treated samples due to dilative behavior. The undrained stress–strain behavior of loose and medium-dense sand transitioned from strain softening to strain hardening as the degree of saturation decreased from 100 to 90%. However, dense sand exhibited strain-hardening behavior with decreased saturation from 100 to 95%. Decreasing saturation levels reduced instability susceptibility, resulting in more stable soil behavior and decreasing the potential for large strains and instability. The study demonstrated a reduction in the Liquefaction Potential Index (LPI) for both loose and medium-dense sand as the degree of saturation decreased from 100 to 90%. These findings highlight the potential of MIPS as an effective technique for mitigating sand liquefaction and offer insights into its underlying mechanisms. [ABSTRACT FROM AUTHOR]