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Aberration-corrected scanning transmission electron microscopy techniques are used to study the bonding configuration between gallium cations and nitrogen anions at defects in metalorganic vapor-phase epitaxy-grown cubic zincblende GaN on vicinal (001) 3C-SiC/Si. By combining high-angle annular dark-field and annular bright-field imaging, the orientation and bond polarity of planar defects, such as stacking faults and wurtzite inclusions, were identified. It is found that the substrate miscut direction toward one of the 3C-SiC ⟨ 110 ⟩ in-plane directions is correlated with the crystallographic [1–10] in-plane direction and that the {111} planes with a zone axis parallel to the miscut have a Ga-polar character, whereas the {111} planes in the zone perpendicular to the miscut direction have N-polarity. The polarity of {111}-type stacking faults is maintained in the former case by rotating the coordination of Ga atoms by 180° around the ⟨ 111 ⟩ polar axes and in the latter case by a similar rotation of the coordination of the N atoms. The presence of small amounts of the hexagonal wurtzite phase on Ga-polar {111} planes and their total absence on N-polar {111} planes is tentatively explained by the preferential growth of wurtzite GaN in the [0001] Ga-polar direction under non-optimized growth conditions. [ABSTRACT FROM AUTHOR]

The SUS304/45 multilayer steels with laminated/network coupling interfaces were fabricated by cold rolling, and the interface evolution behavior and strengthening–toughening mechanism were clarified by microstructure characteristics, tensile testing, and detailed finite element analysis. The results show that when the cold rolling reduction increases from 75 to 87.6 pct, the interface transitions from straight to wavy, and finally forms a laminated/network coupling interface (i.e., the reconstruction of the "Damascus pattern"). The coupling interface is attributed to the uncoordinated deformation of two constituent layers with different crystal structures and stacking fault energy during the cold rolling deformation process. The commercial finite element software ABAQUS was used to simulate the rolling process with different reduction ratios, and the formation mechanism of the laminated/network coupling interface structure is attributed to incoordination deformation of heterogeneous layers. The laminated/network coupling interface and deformation microstructure of constituent layers were further optimized by annealing treatment. The multilayer steel annealed at 700 °C for 30 minutes had the best strength–toughness combination, which is due to the synergistic effect of solid solution, grain refining, dislocation and heterogeneous deformation-induced strengthening. This work provides a novel design idea for strengthening–toughening multilayer steels. [ABSTRACT FROM AUTHOR]

The Gibbs Free energy is a driving force for equilibrium crystal shapes and the formation of crystal facets in molecular crystals. Orientation dependence of interfacial properties is linked to surface free energy (SFE). Prediction of orientation‐dependent properties such as thermal stability, mechanical response, and compatibility with binders require a systematic approach to the quantification of SFE. In molecular crystals, entropy has a much larger contribution among all ordered crystalline materials. In this paper, we extend our previously developed method to quantify SFE and entropy of β‐HMX to other common energetic materials–TATB, α‐RDX, and PETN. Two complimentary approaches, Nonequilibrium Thermodynamic Integration (NETI) and Steered Molecular Dynamics (SMD) methods are used to obtain insight into interfacial phenomena along with surface free energy estimates. We discuss the relevance of surface free energy and the importance of surface entropy for facetted molecular crystals in understanding crystal properties, activation of slip planes, and potential pathways for fracture. These values allow us to predict theoretical crystal shape using Wulff Construction, better understand the effect of hydrogen bonding on SFE, and the diversity of bonding environment in energetic crystals. In particular, in crystals with low stacking fault energy, the SMD values can be inconclusive due to the triggering of slip plane motions. In cases where SMD simulations lead to large deformations and high uncertainty, the NETI approach can still provide SFE estimates. [ABSTRACT FROM AUTHOR]

The γ-surface represents the energetic cost associated with relative, rigid body sliding of crystal planes and contains useful information related to plastic deformation of the respective crystal. Here, we present γ-surfaces for the most active glide planes of the energetic molecular crystal cyclotetramethylene-tetranitramine in the monoclinic β phase, i.e., (101) and (011), at pressures up to 15 GPa. We observe the existence of stable staking faults in both planes and at all pressures and report the increase in the stacking fault energy with pressure. We also report the energetic barriers for sliding along minimum energy paths in various directions contained in these planes as well as the critical resolved shear stress at which the crystal becomes unstable in the absence of crystal defects. [100] traces of the γ-surface for multiple planes such as (001), (010), and (021) are further evaluated in view of the previously reported importance of this slip direction for dislocation cross-slip. It is observed that increasing the pressure does not modify the topology of the γ-surface in an essential way, which implies that although barriers for slip increase, the general phenomenology of dislocation motion is not modified qualitatively by the pressure. The energy barriers increase faster with pressure in the (011) plane, and hence, it is implied that the (101) plane is the most active glide plane at high pressures. The results are generally relevant for studies of plastic deformation in this molecular crystal. [ABSTRACT FROM AUTHOR]

Frank-type stacking faults in 4H–SiC epitaxial layers were investigated using room-temperature photoluminescence mapping and high-angle annular dark-field high-resolution scanning transmission electron microscopy. Remarkably, the intrinsic Frank-type stacking fault (5,2) and intrinsic multilayer Frank-type stacking fault (4,2), which have been reported to have elongated triangular shapes to date, were found to have broader triangular shape, which was typical shape of Shockley-type stacking faults. The shaping of stacking faults could be explained based on the directions of the partial dislocations bounding the stacking faults. Formation models for the intrinsic (5,2) and (4,2) stacking faults were proposed. In addition, we observed Frank-type stacking faults (3,2,2,3) and (3,3) and Shockley-type stacking faults (3,3,3,2,3,2) and (3,2,3,3,3,2), which were not reported before. All of these stacking faults were composed with the stacking numbers 2 and 3 in the Zhdanov notation and showed very close characteristic photoluminescence emission wavelengths of 427–428 nm. Formation models for the stacking faults of (3,2,2,3), (3,3), (3,3,3,2,3,2), and (3,2,3,3,3,2) were proposed, also. Based on the proposed formation models of (4,2) and (3,3) stacking faults, formation models for the Frank-type stacking faults (4,1) and (3,2) were discussed. Finally, we pointed out that the (4,1) Frank-type stacking fault should be the intrinsic not the extrinsic fault, and the (3,2) Frank-type stacking fault is the extrinsic fault. [ABSTRACT FROM AUTHOR]

The formation mechanism of half-loop arrays (HLAs) that form parallel (horizontal) to the step-flow direction in 120 μm thick 4H-silicon carbide (SiC) epitaxial layers was investigated using ultraviolet photoluminescence (UVPL) imaging and x-ray topography (XRT). The horizontal-HLAs are generated by the multiplication and glide of basal plane dislocation (BPD) loops that are created within the epitaxial layer. The BPD loops were initiated after ∼40–50 μm of growth from a small BPD segment, which glides toward the surface as well as the substrate interface. BPD multiplication occurs and several loops are generated. Some of these loops are terminated by the growth front and create HLAs due to the 4° offcut of the wafer. XRT images show that successive BPD loops interact with previously generated HLA segments. Successive loops also interact with the moving growth front and create new HLAs that are spatially displaced from the previous HLA segments. These appear as a string of horizontal-HLAs in the UVPL images. The expansion of stacking faults (SFs) from these horizontal-HLAs was investigated, and we show that they all lie on the same basal plane. The complex defect structure is created in the epitaxial layer from a single BPD loop but extends over a large (∼5 × 0.5 cm2) region of the SiC wafer during epitaxial growth. The high density of HLAs and BPDs would generate several SFs upon device operation leading to severe device degradation. [ABSTRACT FROM AUTHOR]

We investigate the microscopic pathway of spontaneous crystallization in the ST2 model of water under deeply supercooled conditions via unbiased classical molecular dynamics simulations. After quenching below the liquid–liquid critical point, the ST2 model spontaneously separates into low-density liquid (LDL) and high-density liquid phases, respectively. The LDL phase, which is characterized by lower molecular mobility and enhanced structural order, fosters the formation of a sub-critical ice nucleus that, after a stabilization time, develops into the critical nucleus and grows. Polymorphic selection coincides with the development of the sub-critical nucleus and favors the formation of cubic (Ic) over hexagonal (Ih) ice. We rationalize polymorphic selection in terms of geometric arguments based on differences in the symmetry of second neighbor shells of ice Ic and Ih, which are posited to favor formation of the former. The rapidly growing critical nucleus absorbs both Ic and Ih crystallites dispersed in the liquid phase, a crystal with stacking faults. Our results are consistent with, and expand upon, recent observations of non-classical nucleation pathways in several systems. [ABSTRACT FROM AUTHOR]

Metallic alloys with high strength and large ductility are required for extreme structural applications. However, the achievement of ultrahigh strength often results in a substantially decreased ductility. Here, we report a strategy to achieve the strength-ductility synergy by tailoring the alloy composition to control the local stacking fault energy (SFE) of the face-centered-cubic (fcc) matrix in an L12-strengthened superlattice alloy. As a proof of concept, based on the thermodynamic calculations, we developed a non-equiatomic CoCrNi2 (Al0.2 Nb0.2) alloy using phase separation to create a near-equiatomic low SFE disordered CoCrNi medium-entropy alloy matrix with in situ formed high-content coherent Ni3 (Al, Nb)-type ordered nanoprecipitates (~ 12 nm). The alloy achieves a high tensile strength up to 1.6 GPa and a uniform ductility of 33%. The low SFE of the fcc matrix promotes the formation of nanotwins and parallel microbands during plastic deformation which could remarkably enhance the strain hardening capacity. This work provides a strategy for developing ultrahigh-strength alloys with large uniform ductility. [ABSTRACT FROM AUTHOR]

Here we investigated the nucleation of the Re, Ru-rich δ phase affected by stacking faults in the γ phase in a 4th generation Ni-based single crystal superalloy during the service at 800°C. The stacking faults in the γ phase were rich in Re and Ru, similar to the observed δ phase. And the stacking fault regions possessed a similar structure to the δ phase, promoting the transformation from γ phase to δ phase. Furthermore, the calculation results indicated that Ru had more significant promoting effects on the δ phase precipitation than Re, providing a reference for the alloy design. [ABSTRACT FROM AUTHOR]

A stacking fault (SF) that expanded from an interfacial dislocation (ID), which was formed from a basal plane dislocation (BPD) during high-temperature annealing, and its expansion process were investigated by electroluminescence imaging during a current stress test, and by various crystal analyses. The SF was observed during electroluminescence observation of PIN diodes that had line-and-space anodes with open windows. The SF started to expand from the surface side of the ID at low current densities, changed its shape variously, and finally became a parallelogram. A dislocation line inside the expanded parallelogram-shaped SF indicated that the origin was not a single BPD. Cross-sectional high-resolution transmission electron microscopy revealed another SF that was a (3 2 1 2) stacking structure between two single Shockley stacking fault (1SSF) regions at that dislocation line. In addition, the tetrahedra of the two 1SSFs were face-to-face and were offset by two layers. This result means that the original structure of the 1SSFs was a BPD-threading edge dislocation (TED) structure with two BPD segments. The two BPD segments had rotational twin-like structures forming a dislocation loop with each other and the TED between them was present in only two layers. A crystallographic analysis to investigate the expansion mechanism showed consistent results, with the two types of dislocation loops and extinction of the same types of partial dislocations of the Si-core and the C-core. [ABSTRACT FROM AUTHOR]

The expanding shapes of the double-rhombic single Shockley-type stacking faults (DRSFs) from half-loop array (HLA)-type basal plane dislocations (BPDs) and non-HLA-type BPDs were investigated by combining photoluminescence imaging and ultraviolet light illumination. The expansion rate of HLA-type DRSFs was found to increase rapidly after coalescence between neighboring DRSFs. It is thought that the 90° silicon-core [Si(g)] partial dislocation (PD) was a candidate for an expanding front that contributes to extremely rapid expansion of DRSFs. This might be one of the first reports on experimental observations of expanding 90° Si(g) PDs. The 90° Si(g) PDs also seemed to correlate to the symmetry of DRSF shapes for both HLA-type and non-HLA-type DRSFs, and the possibility of every intermediate symmetry was considered by introducing a proportion factor which is defined by combining two running BPD line directions at the origin within the same Burgers vector and glide type. [ABSTRACT FROM AUTHOR]

High density (99.5%) ceramic composite composed of titanium boride and boron carbide (70/30 vol%) was obtained by spark plasma sintering and was tested by 3-point bending test in Ar atmosphere at 1800 °C. Bending strength was high, around 1.1 GPa. The strength–strain curve presents a peculiar shape composed of three regions where elastic and plastic deformations are active with a different weight. Based on transmission electron microscopy observations we propose a process of mechanical energy absorption driven by shear stress in the boron carbide crystals: stacking faults with (1-11) and (011) stacking planes and twins with (1-11) twinning plane rearrange into nano-twins with (10-1) twinning planes, orthogonal but equivalent to the initial ones. This rearrangement mechanism provides in the first instance a plastic signature, but further contributes strengthening. [ABSTRACT FROM AUTHOR]

Topologically protected flat surface bands make thin films of rhombohedral graphite an appealing platform for searching for strongly correlated states of 2D electrons. In this work, rhombohedral graphite is studied with a twin boundary stacking fault and the semimetallic and topological properties of low‐energy bands, localized at the surfaces and at the twinned interface, are analyzed. An effective 4‐band low energy model is derived, where the full set of Slonczewski–Weiss–McClure (SWMcC) parameters is implemented, and the conditions for the bands are found to be localized at the twin boundary, protected from the environment‐induced disorder. This protection together with a high density of states at the charge neutrality point, in some cases—due to a Lifshitz transition, makes this system a promising candidate for hosting strongly‐correlated effects. [ABSTRACT FROM AUTHOR]

The grain boundaries and dislocations play an important role in understanding the deformation behavior in polycrystalline materials. In this paper, the deformation mechanism of Cu, Ni, and equimolar Cu-Ni alloy was investigated using molecular dynamic simulation. The interaction between dislocations and grain boundary motion during the deformation was monitored using the dislocation extraction algorithm. Moreover, the effect of stacking fault formation and atomic band structure on the deformation behavior was discussed. Results indicate that dislocations nucleate around the grain boundary in copper, the deformation in nickel changes from planar slip bands to wavy bands, and high density of dislocation accumulation as well as numerous kink and jog formations were observed for the equimolar Cu-Ni alloy. The highest density of the Shockley dislocation and stacking faults was formed in the equimolar Cu-Ni alloy which results in the appearance of a huge gliding stage in the stress–strain curve. The grain boundaries act as a sinking source for vacancy annihilation in Ni and Cu; however, this effect was not observed in an equimolar Cu-Ni alloy. Finally, radial distribution function was used to evaluate atom segregation in grain boundaries. [ABSTRACT FROM AUTHOR]

X-ray diffraction analysis is essential in studying stacking faults. Most of the techniques used for this purpose are based on theoretical studies. These studies suggest that the observed diffraction patterns are caused by random stacking faults in crystals. In reality, however, the condition of randomness for stacking faults may be violated. The purpose of the study was to develop a technique that can be used to calculate the diffraction effects of the axis of the thin plates of twin, new phases, as well as other variations in defective structures. Materials and methods. This was achieved through modern X-ray diffraction methods using differential equations (transformations and Fourier transforms) and the construction of the Ewald sphere, mathematical analysis, mathematical logic, and mathematical modeling (complex Markov chain). Conclusion. The study made it possible to develop a technique for the calculation of the diffraction effects of the axis of the thin plates of twin, new phases and other variations in defective structures. The technique makes it possible to solve several complex, urgent problems related to the calculation of X-ray diffraction for crystals with face-centered lattices containing different types of stacking faults. At the same time, special attention was paid to the correlations between the relative positions of faults. The calculations showed that the proposed method can help to determine the nature and structure of stacking faults by identifying the partial and vertex dislocations limiting them in twin crystals with a face-centered cubic structure of silicon carbide based on X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

X-ray diffraction and bright-field transmission electron microscopy are used to investigate the distribution and density of {111}-type stacking faults (SFs) present in a heteroepitaxial zincblende GaN epilayer with high phase purity, grown on a 3C-SiC/Si (001) substrate by metalorganic vapour-phase epitaxy. It is found that the 4° miscut towards the [110] direction of the substrate, which prevents the formation of undesirable antiphase domains, has a profound effect on the relative densities of SFs occurring on the different {111} planes. The two orientations of SFs in the [−110] zone, where the SF inclination angle with the GaN/SiC interface is altered by the 4° miscut, show a significant difference in density, with the steeper (111) SFs being more numerous than the shallower (−1−11) SFs by a factor of ∼5 at 380 nm from the GaN/SiC interface. In contrast, the two orientations of SFs in the [110] zone, which is unaffected by the miscut, have densities comparable with the (−1−11) SFs in the [−110] zone. A simple model, simulating the propagation and annihilation of SFs in zincblende GaN epilayers, reproduces the presence of local SF bunches observed in TEM data. The model also verifies that a difference in the starting density at the GaN/SiC interface of the two orientations of intersecting {111} SFs in the same zone reduces the efficiency of SF annihilation. Hence, (111) SFs have a higher density compared with SFs on the other three {111} planes, due to their preferential formation at the GaN/SiC interface caused by the miscut. [ABSTRACT FROM AUTHOR]

The formation of single Shockley stacking faults (SSSFs) in 4H-SiC crystals under non-equilibrium conditions (e.g., the forward biasing of PiN diodes and ultraviolet light illumination) is a key phenomenon in the so-called bipolar degradation of SiC power devices. This study theoretically investigated the physical mechanism of this phenomenon based on the concept of quantum well action. As a first approximation describing the non-equilibrium state of the material, we employed quasi-Fermi level approximation. We then made improvements by considering several physical effects governing the carrier distribution near and in the SSSF. The improved model accounts well for the excitation threshold and the temperature dependence of SSSF expansion. Thus, the model provides useful insights into the driving force of SSSF expansion under non-equilibrium conditions. [ABSTRACT FROM AUTHOR]

The defect evolution associated with an anomalous work hardening behavior of a single crystalline quaternary Co-Al-W-Ta superalloy at 950 °C was investigated by transmission electron microscopy. As plastic deformation is initially confined to the γ matrix channels, a plateau arises in the stress-strain curve after yielding. At about 1% plastic strain, extensive shearing of the γ′ precipitates under superlattice stacking fault formation occurs leading to extreme work hardening rates up to 12 GPa and a total increase in stress of about 200 MPa. Additional investigations on the temperature and strain-rate dependence of the anomalous work hardening behavior reveal the significance of diffusion and segregation processes on the stress-strain curve and the work hardening behavior. [ABSTRACT FROM AUTHOR]

This study introduces an alternative method to the Takagi–Taupin equations for investigating the dark‐field X‐ray microscopy (DFXM) of deformed crystals. In scenarios where dynamical diffraction cannot be disregarded, it is essential to assess the potential inaccuracies of data interpretation based on the kinematic diffraction theory. Unlike the Takagi–Taupin equations, this new method utilizes an exact dispersion relation, and a previously developed finite difference scheme with minor modifications is used for the numerical implementation. The numerical implementation has been validated by calculating the diffraction of a diamond crystal with three components, wherein dynamical diffraction is applicable to the first component and kinematic diffraction pertains to the remaining two. The numerical convergence is tested using diffraction intensities. In addition, the DFXM image of a diamond crystal containing a stacking fault is calculated using the new method and compared with the experimental result. The new method is also applied to calculate the DFXM image of a twisted diamond crystal, which clearly shows a result different from those obtained using the Takagi–Taupin equations. [ABSTRACT FROM AUTHOR]

Schwarz crystals with uniformly distributed twins enclosed by general grain boundaries (GBs) resembling triply minimal-surfaces were observed in high stacking fault energy metal Pt which is believed not readily to twin. By refining the grains of pure Pt from 140 μm to several nanometers via plastic deformation technique, deformation twins were found to emerge numerously and the structural morphologies of Schwarz crystals can be identified at grain sizes below 4 nm. Both experiments and atomistic simulations suggest that Pt Schwarz crystals are thermally stable at temperatures approaching the thermal equilibrium melting point. The measured room temperature microhardness as a function of grain size, on the other hand, may increase monotonically up to 12.9 GPa, revealing a sustained Hall-Petch relationship. The observed outstanding mechanical stabilities can be attributed to that, regardless of the critical twin size and the stacking fault energy of the material, the plastic deformation at the grain size limit is solely limited by twinning and both the nucleation and bowing-out of twinning partial dislocations from GB sources are notoriously difficult according to simulations and theory. [Display omitted] [ABSTRACT FROM AUTHOR]

Because the expansion of single Shockley stacking faults (1SSFs) is an important problem for the viability of SiC bipolar devices, there is a need to suppress it during device operation. The expansion mechanism, however, is still unclear. Therefore, the method to suppress the expansion has never been established. An important factor for the expansion could be carrier recombination in 1SSFs because the expansion has only been observed during bipolar operation or light illumination. In this study, we characterized carrier recombination by observing the photoluminescence from 1SSFs and partial dislocations (PDs). The luminescence from 1SSFs and PDs showed a fast decay component compared with that from the band edge. This result indicates that the carrier recombination in 1SSFs and at PDs was faster than that in regions without 1SSFs in 4H-SiC. In addition, because of the slower recombination at Si-core PDs compared with that in 1SSFs and at C-core PDs, the velocity of 1SSF expansion would be limited by the carrier recombination at Si-core PDs. The temperature dependence of the decay time implies that the recombination at the Si-core PD was enhanced on increasing the temperature. [ABSTRACT FROM AUTHOR]

MAX phases are layered carbides or nitrides with the general formula Mn+1AXn, which exhibit a unique combination of ceramic- and metal-like properties. The effect of stacking a number (determined by n) remains to be elucidated and a priori is not clear whether, for a given chemistry, n significantly changes the intrinsic deformation behavior of these systems. In this work, we have studied the intrinsic deformation behavior of Tin+1AlCn and Tan+1AlCn (n = 1 … 5) using DFT-based calculations. Surprisingly, the results suggest that the stacking number tends to have a minimal effect on the intrinsic mechanical behavior of the systems studied. [ABSTRACT FROM AUTHOR]

The expansion behavior of a single Shockley stacking fault (SSSF) originating from a basal plane dislocation in a 4H-SiC epitaxial layer on the (11 2 ¯ 0) a-plane under electron beam (EB) (//[11 2 ¯ 0]) irradiation was observed. The width of the SSSF was proportional to the EB current. EB irradiation at a fixed spot outside an SSSF can expand the SSSF as effectively as direct SSSF irradiation. It was found that the selective excitation of an SSSF and/or a Si-core partial dislocation (PD) is possible by appropriately setting the EB irradiation position because the cathodoluminescence spectrum varies with the irradiation position around an SSSF. The rate of SSSF expansion upon the indirect excitation of a Si-core PD is much larger than that upon direct SSSF excitation. However, the expansion rate under both indirect SSSF excitation and indirect Si-core PD excitation is smaller than that under indirect Si-core excitation. The C-core PD became mobile after supplying a threshold number of electron-hole pairs. [ABSTRACT FROM AUTHOR]

Dislocations introduced by the scratching or by the indentation of the basal and prismatic surfaces of low-ohmic unintentionally n-type doped GaN crystals were investigated by means of cathodoluminescence and transmission electron microscopy (TEM). A strong luminescence of straight segments of a-screw dislocations was observed in the temperature range of 70–420 K. The spectrum of dislocation related luminescence (DRL) consisted of a doublet of narrow lines red shifted by about 0.3 eV with respect to the band gap. TEM revealed dissociated character of the screw dislocations and the formation of extended nodes at their intersection. From the analysis of the DRL spectral doublet temperature, power and strain dependences DRL was ascribed to direct and indirect excitons bound by 1D quantum wells formed by partials and stacking fault (SF) ribbon of dissociated screw dislocation. [ABSTRACT FROM AUTHOR]

As often observed for supramolecules, a crystal of a Ta-based peanut-shaped supramolecule [{Cp′′Ta(CO)2(η4-P4)}10{CuI}14] (1) decays under X-rays. Unexpectedly, a solid-to-solid transformation evidenced by a unit cell change took place on irradiation prior to the complete decay. This unusual behaviour was studied with the same single crystal of 1. According to the results of the structure refinement interpreted using OD theory, crystals of 1 continuously change their macro-structure which is accompanied by an increase of space group symmetry and by vanishing of crystallographic disorder. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) can induce severe plastic deformation in the surface zone of metallic materials, which potentially enhances their mechanical properties. Although it is widely recognized that the improvement of mechanical properties can be attributed to microstructure evolution, the microstructural characteristics and response under different LSP parameters are complex, leading to distinct mechanical behaviors of materials at the macroscale. Besides, the exceedingly brief duration of LSP also poses considerable challenges to capture the microstructure evolution within the surface layer of materials. Therefore, to grasp a first in-situ atomistic insight into LSP response of α-titanium, molecular dynamics method is applied to simulate laser incidence at the [ 10 1 ¯ 0 ] crystallographic orientation with various energy densities. The results show that the lattice reorientation and dislocation slip dominate the plastic deformation at low laser energy density, while stacking faults and crystal disordering are the primary microstructural features at high laser energy density. The above shock-induced microstructures are verified by transmission electron microscopy (TEM) observations. Further, varied microscale plastic deformation modes under varying shock energies are proposed based on Schmid factors and energy barriers. The findings bridge laser energy to post-processing microstructure of α-titanium, which paves the way for improving mechanical properties of materials by optimizing LSP treatment parameters. [Display omitted] [ABSTRACT FROM AUTHOR]

We investigated the structures and expansion behavior of double-Shockley stacking faults (DSFs) formed in heavily nitrogen-doped 4H-SiC during annealing. Heavily doped epilayers prepared as specimens were successively annealed. Various types of DSFs showing different shapes and dislocation contrasts were found in photoluminescence and synchrotron X-ray topography images. Taking account of every possible stacking sequence forming DSFs, the structures of various types of DSFs were determined from observations by plan-view transmission electron microscopy (TEM) and cross-sectional high-angle annular dark-field scanning TEM. We found that a bounding dislocation enclosing a DSF splits into two partial dislocations (PDs), and their Burgers vectors are identical, while the distance of the two PDs depended on their core structures (30° Si-, 30° C- or 90° C-core). We also discussed the contrast rule for the dislocation consisting of two PDs in the synchrotron X-ray topography images and the mobile PDs for the DSF expansion in the epilayers with different nitrogen concentrations. [ABSTRACT FROM AUTHOR]

Planar defects, such as stacking faults and twins, are the most common defects in III-V semiconductor nanowires. Here we report on the effect of surface perturbation caused by twin planes on surface optical (SO) phonon modes. Self-catalyzed GaAs nanowires with varying planar defect density were grown by molecular beam epitaxy and investigated by Raman spectroscopy and transmission electron microscopy (TEM). SO phonon peaks have been detected, and the corresponding spatial period along the nanowire axis were measured to be 1.47 μm (±0.47 lm) and 446 nm (±35 nm) for wires with twin densities of about 0.6 (±0.2) and 2.2 (±0.18) per micron. For the wires with extremely high density of twins, no SO phonon peaks were detected. TEM analysis of the wires reveal that the average distance between the defects are in good agreement with the SO phonon spatial period determined by Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Using event-driven Brownian dynamics simulations, we investigate the epitaxial growth of hardsphere crystals with a face-centered-cubic (fcc) structure on the three densest cross-sectional planes of the fcc: (i) fcc (100), (ii) fcc (111), and (iii) fcc (110). We observe that for high settling velocities, large fcc crystals with very few extended defects grow on the fcc (100) template. Our results show good agreement with the experiments of Jensen et al. [Soft Matter 9, 320 (2013)], who observed such large fcc crystals upon centrifugation on an fcc (100) template.We also compare the quality of the fcc crystal formed on the fcc (111) and fcc (110) templates with that of the fcc (100) template and conclude that the latter yields the best crystal.We also briefly discuss the dynamical behavior of stacking faults that occur in the sediments. [ABSTRACT FROM AUTHOR]

Even though the fundamental rules governing dislocation activities have been well established in the past century, we report a phenomenon, dislocation transformation, governed by the generalized-stacking-fault energy surface mismatch (GSF mismatch for short) between two co-existing phases. By carrying out ab-initio-informed microscopic phase-field simulations, we demonstrate that the GSF mismatch between a high symmetry matrix phase and a low symmetry precipitate phase can transform an array of identical full dislocations in the matrix into an array of two different types of full dislocations when they shear through the precipitates. The precipitates serve as a passive Shockley partial source, creating new Shockley partial dislocations that are neither the ones from the dissociation of the full dislocation. This phenomenon enriches our fundamental understanding of partial dislocation nucleation and dislocation-precipitate interactions, offering additional opportunities to tailor work-hardening and twinning processes in alloys strengthened by low-symmetry precipitate phases. [ABSTRACT FROM AUTHOR]

Deformation twinning and dislocation slip in twinning-induced plasticity (TWIP) steels have been shown to depend strongly on the crystal orientation, yet the underlying mechanism is still unclear. Here, we addressed this question by fabricating single crystal micro-pillars with six different crystal orientations in a coarse-grained TWIP steel sample and then conducting compression tests as well as microstructural characterization in these pillars. Depending on the crystal orientation, either twinning or slip dominates the plastic deformation. The critical stresses for twinning and slip were measured to be 147.5 ± 19.2 and 105.4 ± 11.2 MPa, respectively. It is found that the Schmid factors for the leading and trailing partial dislocations on the primary slip plane play a crucial role in the competition between twinning and slip at different orientations. Besides, the occurrence of cross-slip depends on crystal orientation through the Schmid factors for the constriction of extended dislocation cores on the primary slip plane as well as those for cross-slip on the conjugate slip plane. [ABSTRACT FROM AUTHOR]

The effect of W, Mo, V, Ta, and Nb, five common β-stabilizing substitutional elements, on α-Ti stacking fault energy has been studied using first principle calculations. The generalized stacking fault energy (GSFE) curves have been determined for different concentrations of β-stabilizers at the fault plane using supercells with up to 360 atoms. Both basal and prismatic slip systems with the stable (γSF) and unstable (γUSF) stacking faults and twinning fault energies were determined. All the alloying elements reduce the stacking fault energy for Ti for both basal and prismatic slip. At higher concentration of 25 at. % of V, Ta, and Nb at the slip plane, the basal slip becomes more favorable than the prismatic slip in Ti. Ti-Mo and Ti-W systems also show a significant shift in the GSFE curve towards a higher shear deformation strain along <0110> due to the change in bond character between Ti and those two elements. Using Rice criterion, which employs γS/γUSF ratio to estimate ductility, we show that all the alloying elements likely improve the ductility of α-Ti with Ti-25 at. % Nb exhibiting the most ductile behavior. However, according to the Tadmor and Bernstein model, all the alloying elements considered here do not improve the partial dislocation emission or the twinning propensity in spite of decreasing the stacking fault energies for α-Ti and. Hence, a better empirical model that incorporates changes in the character of directional bonding upon alloying is needed to estimate how alloying influences ductility in hcp metals. [ABSTRACT FROM AUTHOR]

The correlation of microstructural development and the kinetics of film growth has been investigated during the epitaxial film growth of an ultrathin binary Ag0.93Al0.07 solid solution on a Si(111)-7?7 surface at 300K by the combination of high-resolution transmission electron microscopy, X-ray diffraction, scanning tunneling microscopy, low energy electron diffraction, and realtime in-situ stress measurements. Up to a film thickness of 6±2 nm, epitaxial Ag0.93Al0.07 film growth is characterized by the strikingly extensive formation of planar faults parallel to the film/ substrate interface, while at larger thickness the film grows practically defect-free. As revealed by real-time in-situ stress measurements, the extensive formation of planar faults at the very initial stage of growth is not driven by the reduction of the system's elastic strain energy but is rather caused by a striking thickness-dependence of the stacking-fault energy owing to a quantum size effect of the ultrathin metal alloy film, resulting in a frequent succession of fcc and hcp stackings of close-packed layers during the initial stage of film growth. The extensive development of planar faults at the initial stage of film growth (<6±2 nm) is associated with the occurrence of a high density of kinks and corners at thereby atomically rough surface ledges, which strongly enhances the downward transport of adatoms from higher to lower terraces (interlayer mass transport) by a reduction of the effective diffusion barrier at the edge of surface steps and by increasing the driving force for adatoms to attach to the surface ledges. As a result, the epitaxial Ag0.93Al0.07 film initially grows in a 2D layer-by-layer type of growth and thus establishes atomically smooth film surfaces. For the practically planar-fault-free growth at thicknesses beyond 6±2 nm, interlayer mass transport becomes distinctively limited, thereby inducing a transition from 2D to 3D type of film growth. [ABSTRACT FROM AUTHOR]

The microstructure of polycrystalline PbTe1-xSex-ZnSe composite thin films has been studied by scanning transmission electron microscopy and electron diffraction. The films were prepared by the one-step synthesis method using simultaneous evaporation of PbTe and ZnSe. The nanocrystals of PbTe1-xSex are formed in a ZnSe matrix. Tellurium concentration can be tuned by controlling the PbTe evaporation source temperatures between 753K and 793 K. Binary PbSe nanocrystals were formed at 753 K, while ternary PbTe1-xSex nanocrystals were formed at 793 K. The nanocrystals grow in a granular shape at the initial stage of film growth, and the morphology changes to nanowire-shape as the film grows, irrespective of the Te concentration. The ternary PbTe1-xSex nanocrystals were composed of two phases with different Te concentration; Te-rich (Se-poor) granular crystals were formed near the bottom half parts of the film and Te-poor (Se-rich) nanowires were formed at the upper half parts of the film. Columnar ZnSe crystals contain high-density {111} stacking faults due to the low stacking fault energy of ZnSe. A balance of deposition and reevaporation on the substrate during the film growth will be responsible for the resultant nanocrystal morphology. [ABSTRACT FROM AUTHOR]

The molecular dynamics simulation method is used to investigate the dependence of crystal orientation and shock wave strength on dislocation density evolution in single crystal Cu. Four different shock directions h100i, h110i, h111i, and h321i are selected to study the role of crystal orientation on dislocation generation immediately behind the shock front and plastic relaxation as the system reaches the hydrostatic state. Dislocation density evolution is analyzed for particle velocities between the Hugoniot elastic limit (upHEL) for each orientation up to a maximum of 1.5 km/s. Generally, dislocation density increases with increasing particle velocity for all shock orientations. Plastic relaxation for shock in the h110i, h111i, and h321i directions is primarily due to a reduction in the Shockley partial dislocation density. In addition, plastic anisotropy between these orientations is less apparent at particle velocities above 1.1 km/s. In contrast, plastic relaxation is limited for shock in the h100i orientation. This is partially due to the emergence of sessile stair-rod dislocations with Burgers vectors of 1/3h100i and 1/6h110i. The nucleation of 1/6h110i dislocations at lower particle velocities is mainly due to the reaction between Shockley partial dislocations and twin boundaries. On the other hand, for the particle velocities above 1.1 km/s, the nucleation of 1/3h100i dislocations is predominantly due to reaction between Shockley partial dislocations at stacking fault intersections. Both mechanisms promote greater dislocation densities after relaxation for shock pressures above 34 GPa compared to the other three shock orientations. [ABSTRACT FROM AUTHOR]

Among the major obstacles for development of non-polar and semipolar GaN structures on foreign substrates are stacking faults which deteriorate the structural and optical quality of the material. In this work, an in-situ SiNx nano-network has been employed to achieve high quality heteroepitaxial semipolar (1122) GaN on m-plane sapphire with reduced stacking fault density. This approach involves in-situ deposition of a porous SiNx interlayer on GaN that serves as a nano-mask for the subsequent growth, which starts in the nanometer-sized pores (window regions) and then progresses laterally as well, as in the case of conventional epitaxial lateral overgrowth (ELO). The inserted SiNx nano-mask effectively prevents the propagation of defects, such as dislocations and stacking faults, in the growth direction and thus reduces their density in the overgrown layers. The resulting semipolar (1122) GaN layers exhibit relatively smooth surface morphology and improved optical properties (PL intensity enhanced by a factor of 5 and carrier lifetimes by 35% to 85% compared to the reference semipolar (1122) GaN layer) which approach to those of the c-plane in-situ nano-ELO GaN reference and, therefore, holds promise for light emitting and detecting devices. [ABSTRACT FROM AUTHOR]

The formation of basal plane stacking faults in heavily nitrogen-doped 4H-SiC crystals was theoretically investigated. A novel theoretical model based on the so-called quantum well action mechanism was proposed; the model considers several factors, which were overlooked in a previously proposed model, and provides a detailed explanation of the annealing-induced formation of double layer Shockley-type stacking faults in heavily nitrogen-doped 4H-SiC crystals. We further revised the model to consider the carrier distribution in the depletion regions adjacent to the stacking fault and successfully explained the shrinkage of stacking faults during annealing at even higher temperatures. The model also succeeded in accounting for the aluminum co-doping effect in heavily nitrogen-doped 4H-SiC crystals, in that the stacking fault formation is suppressed when aluminum acceptors are co-doped in the crystals. [ABSTRACT FROM AUTHOR]

Nanomaterials and nanostructures are continuously driving technology revolutions in broad engineering fields, such as defense [[1]], aerospace, electronics [[2]], biomedical [[3]], energy [[5]], and other high-end sectors. Investigations show that CNT acts as a skeleton in the poly phenylene terephthalamide polymer that enhance both the strength and modulus [[32]], and the graphene foam can remarkably increase the storage modulus and loss modulus of the polydimethylsiloxane polymer [[33]]. 33432953 42 Ren K., Qin H., Liu H., Chen Y., Liu X., Zhang G. Manipulating Interfacial Thermal Conduction of 2D Janus Heterostructure via a Thermo-Mechanical Coupling. Landmark nanostructures, such as fullerene [[6]], carbon nanotube (CNT) [[7]], and graphene [[8]], have significantly promoted the growth of nanomaterials and triggered novel applications. [Extracted from the article]

Atomic force microscope (AFM) tip-based nanomilling is an emerging technology for machining nanostructures with a high rate of material removal and slight tip wear. However, subsurface damage induced by nanomilling is poorly understood. In this study, we investigated nanomilling-induced subsurface damage of single-crystal silicon experimentally and with molecular dynamics simulations. We studied the effect of clockwise and anticlockwise trajectories on the nanochannel morphology. The clockwise trajectory resulted in a 'U'-shaped nanochannel at a relatively low normal load. Transmission electron microscopy and Raman spectroscopy analysis of the nanochannel subsurface revealed atomic-scale defects, including dislocations, stacking faults, and amorphous silicon. Molecular dynamics simulations described the evolution of the phase transformation and subsurface damage. This work reveals the mechanism of subsurface damage of single-crystal silicon in nanomilling, which will facilitate the machining of nanostructures with minimal subsurface damage. [Display omitted] • The topographies of nanochannels that fabricated using nanomilling were investigated. • The material removal rates for single scratch and nanomilling were compared. • The subsurface damage for nanomilling using circle trajectory was investigated by TEM and Raman. • The dynamic evolution process of the subsurface damage was revealed by molecular dynamic simulation. [ABSTRACT FROM AUTHOR]

Cubic ice is said to have stacking disorder when the H2O sequences in its structure (space group Fd3m) are interlaced with hexagonal ice (space group P63/mmc) sequences, known as stacking faults. Diffraction methods have shown that the extent of this disorder varies in samples made by different methods, thermal history, and the temperature T, but other physical properties of cubic and hexagonal ices barely differ. We had found that at 160 K, the thermal conductivity, κ, of cubic ice is ~20% less than that of hexagonal ice, and this difference varies for cubic ice samples prepared by different methods and/or subjected to different thermal history. After reviewing the methods of forming cubic ice, we report an investigation of the effects of stacking disorder and other features by using new data, and by analyzing our previous data on the dependence of κ on T and on the pressure. We conclude that the lower κ of cubic ice and its weaker T-dependence is due mainly to stacking disorder and small crystal sizes. On in situ heating at 20-50 MPa pressure, κ increases and cubic ice irreversibly transforms more sharply to ice Ih, and at a higher T of ~220 K, than it does in ex situ studies. Cooling and heating between 115 and 130 K at 0.1 K min-1 rate yield the same κ value, indicating that the state of cubic ice in these conditions does not change with time and T. The increase in κ of cubic ice observed on heat-annealing before its conversion to hexagonal ice is attributed to the loss of stacking faults and other types of disorders, and to grain growth. After discussing the consequences of our findings on other properties, we suggest that detailed studies of variation of a given property of cubic ice with the fraction of stacking faults in its structure may reveal more about the effect of this disorder. A similar disorder may occur in the mono-layers of H2O adsorbed on a substrate, in bulk materials comprised of two dimensional layers, in diamond and in Zirconium and in numerous other crystals. [ABSTRACT FROM AUTHOR]

Semiconductor nanopillars have unique geometries that make them very promising materials for a variety of devices. In order to improve their performance, we need to understand how they are affected by ridge states that lie on the six corners of the nanopillar hexagon. Although the GaAs nanopillars are primarily zinc blende (ABC), stacking faults of wurtzite (AB) stacking occur. We use density-functional theory to study stacking faults using one-dimensional periodic geometries that have a combination of zinc blende and wurtzite stacking. In contrast to perfect zinc blende nanopillars, energetically favorable midgap ridge states created by stacking faults are found in these geometries using density-functional theory. The calculated band diagrams and densities of state help us to understand how these midgap states lead to a reduced mobility and carrier localization. We also study how sulfur passivation affects and potentially improves the performance by modifying the ridges. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are used to investigate the mechanical behavior of Cu nanowires (NWs) with planar defects such as grain boundaries (GBs), twin boundaries (TBs), stacking faults (SFs), etc. To investigate how the planar defects affect the deformation and fracture mechanisms of naowires, three types of nanowires are considered in this paper: (1) polycrystalline Cu nanowire; (2) single-crystalline Cu nanowire with twin boundaries; and (3) single-crystalline Cu nanowire with stacking faults. Because of the large fraction of atoms at grain boundaries, the energy of grain boundaries is higher than that of the grains. Thus, grain boundaries are proved to be the preferred sites for dislocations to nucleate. Moreover, necking and fracture prefer to occur at the grain boundary interface owing to the weakness of grain boundaries. For Cu nanowires in the presence of twin boundaries, it is found that twin boundaries can strength nanowires due to the restriction of the movement of dislocations. The pile up of dislocations on twin boundaries makes them rough, inducing high energy in twin boundaries. Hence, twin boundaries can emit dislocations, and necking initiates at twin boundaries. In the case of Cu nanowires with stacking faults, all pre-existing stacking faults in the nanowires are observed to disappear during deformation, giving rise to a fracture process resembling the samples without stacking fault. [ABSTRACT FROM AUTHOR]

The anisotropy of X‐ray diffraction scanning of (201) β‐Ga2O3 bulk material has been investigated. Symmetric rocking curves (RCs) exhibit distinctly different broadening along different azimuths, with a maximum along [102] and a minimum along a direction rotated by 30° from [010]. Williamson–Hall analysis was applied to study possible factors causing the broadening in these RCs, including instrumental factors, mosaic tilt and coherent scattering. It was found that the RC broadening is determined by both isotropic mosaic tilt and anisotropy in the length over which the crystal structure is not disrupted by limiting factors such as grain boundaries or stacking faults, which we term the 'lateral limited size'. In this case, the lateral limited size is governed by {200} stacking faults along the [102] direction and grain boundaries along the [010] direction. The result presents a new anisotropy characteristic of (201) β‐Ga2O3. [ABSTRACT FROM AUTHOR]

The anisotropy of X‐ray diffraction scanning of (201) β‐Ga2O3 bulk material has been investigated. Symmetric rocking curves (RCs) exhibit distinctly different broadening along different azimuths, with a maximum along [102] and a minimum along a direction rotated by 30° from [010]. Williamson–Hall analysis was applied to study possible factors causing the broadening in these RCs, including instrumental factors, mosaic tilt and coherent scattering. It was found that the RC broadening is determined by both isotropic mosaic tilt and anisotropy in the length over which the crystal structure is not disrupted by limiting factors such as grain boundaries or stacking faults, which we term the 'lateral limited size'. In this case, the lateral limited size is governed by {200} stacking faults along the [102] direction and grain boundaries along the [010] direction. The result presents a new anisotropy characteristic of (201) β‐Ga2O3. [ABSTRACT FROM AUTHOR]

• Iso-diameter seed promotes convex solid–liquid interface, prevents shouldering. • Simulations effectively optimize CZT crystal growth. • Reproducibility demonstrated with iso -diameter seed VGF method. • Achieved precise control over inclusion/precipitation defects at low densities. • Successfully grew HgCdTe via LPE on CZT substrates. CdZnTe (CZT) is the preferred material for HgCdTe (MCT) infrared detectors and room temperature nuclear-radiation detector applications. However, their widespread application is hindered by the low yield, attributed to intrinsic thermophysical properties like extremely low thermal conductivity and stacking fault energy, complicating the growth of large-volume crystals. Based on steady-state computer numerical modeling simulation, this paper examines the impact of seed size variations (from 15 mm to 90 mm) in the crystal growth process on the initial growth surface morphology, simulations indicate that larger seed crystals are predisposed to developing more convex interfaces, which are conducive to enhanced crystal growth. An optimized Vertical Gradient Freeze (VGF) method employing iso -diameter seed (having the same diameter as the grown crystals) of approximately 90 mm has been developed to grow single crystals with reduced defect density in a VGF furnace, and the applications in liquid phase epitaxy (LPE) are also discussed. [ABSTRACT FROM AUTHOR]

Radiation centers that are generated on the surface of SiC crystals [surface single-photon sources (SPSs)] have received much attention because they behave as high-brightness SPSs at room temperature. However, little is known about surface SPSs, such as their defect structure and radiation properties. To achieve a better understanding of surface SPSs, we investigated the impact of the formation processes of SPSs on the radiation properties. Low temperature photoluminescence (PL) measurements indicated that the photon energies of the zero-phonon line (ZPL) were dispersed in the range of 0.33 eV. In comparison between the (0001) Si-face and (11–20) a-face, the energy dispersion for the a-face was smaller, which suggests that the energy dispersion was attributed to stacking faults at the oxide–SiC interface. The differences in the radiation properties of the surface SPSs were clarified according to the formation process in terms of the oxide thickness and post-oxidation Ar annealing. The results showed that the wavelength dispersion was increased with the oxide thickness, and Ar annealing caused various changes in the radiation properties, such as a reduction in the density of SPSs, and the radiation intensity of the ZPL as well as a shift in the ZPL wavelength. Notably, most of the changes in the defect structure occurred at the Ar anneal temperature of 600 °C, and we discuss some of the types of defects that change at this temperature. [ABSTRACT FROM AUTHOR]

The effect of the structural features of self-activated zinc selenide and crystals with activators on the emission spectra is investigated in band anticrossing theory. Numerous contradictory published data make it difficult to understand this issue. Band anticrossing theory in its current statement requires taking into account the effect of the isoelectronic oxygen impurity, which inevitably exists in the ZnSe lattice, on the band structure. The development of methods for calculating the equilibrium of intrinsic point defects suggests the use of these data in analyzing the optical properties of AII–BIV compounds, including zinc selenide. The study is aimed at examining the features and nature of individual luminescence bands widely used to obtain information about crystal quality. The photoluminescence, cathodoluminescence, and pulsed luminescence spectra, as well as the excitation and stimulated emission spectra of ZnSe are investigated with the use of these features in a single context, taking into account the noted features. The stable states of crystals with stacking faults upon embedding activators or a background copper impurity are established. The data are of interest for the diagnostics of crystals applicable in lasers. [ABSTRACT FROM AUTHOR]

Understanding the evolution of dislocations and twinning at the crack front is critical for designing micro-mechanical systems with improved performance. In this work, the dislocation evolution at the crack front in thin pre-cracked FCC single crystals is correlated with the associated fracture toughness, which is shown to be dependent on material specific properties such as stable stacking fault energy (γ s s f) and crystal orientation using atomistic simulations. For materials with high γ s s f value, sessile dislocations form at the crack front causing increased localised plastic flow stress that leads to low fracture toughness. Whereas the fracture process in materials with low γ s s f value is governed by the motion of glissile dislocations and stress-induced twinning leads to high fracture toughness. For this case, twinning occurs at high stress levels followed by un-twinning due to stress relaxation at crack front by twinning. The crystal orientation influences the type of dislocations emitted (screw/edge) from the crack front which governs the mode of crack propagation. The Mode-III crack propagation by the emission of screw type dislocations causes significant decrease in the fracture toughness compared to Mode I crack propagation which is caused by simultaneous emission of edge type dislocations on the two symmetrically inclined slip planes at the crack front. For certain pre-cracked crystal orientations, twinning is seen during the early stages of plastic deformation in materials with high γ s s f value. However, un-twinning is not observed in crystal orientation-based twinning at the crack front. [ABSTRACT FROM AUTHOR]

Tensile deformation behavior of high-strength nanostructured CuSi solid-solution alloys processed by high-pressure torsion (HPT) with 5 rotations was investigated at room and low temperatures. With increasing Si concentration, tensile strength of the nanostructured CuSi solid-solution alloys was significantly increased. The maximal tensile strengths were 980 MPa at room temperature, and 1350MPa at 77K in a Cu2.04 wt.%Si alloy. This significant strengthening was achieved by grain refinement and increased dislocation density through severe plastic deformation (SPD) with the effect of Si addition on the decreasing stacking fault energy of the CuSi alloy. With increasing Si concentration, strain-rate sensitivity m of the nanostructured CuSi solid-solution alloys was decreased due to the increased dislocation density, resulting in accelerating plastic instability of tensile specimens, caused by the diminishing strain-rate hardening capacity after necking. [ABSTRACT FROM AUTHOR]