Understanding the mechanical behavior of bimetallic nanoparticles under compressive stress is relevant for the use of these nanostructures in catalysis and nanomechanics. In this work, we present molecular dynamics (MD) simulations of compressive deformation in Pt–Ni nanoparticles—and bulk systems for comparison—with varying compositions (PtxNi1−x) and local distributions. The simulations show that the mechanical response is governed by local strain fields, which influence both elastic and plastic regimes. The final trajectories were analyzed by dislocation analysis (DXA), simulated STEM imaging, and geometric phase analysis (GPA), which allowed the obtention of high-resolution strain maps. Analysis of von Mises stress distribution allowed us to correlate composition and atomic ordering with the formation and evolution of dislocations in the nanoparticles. The Pt0.5Ni0.5 intermetallic compound exhibits superior mechanical performance under uniaxial compression; in bulk, this composition also shows enhanced elastic energy storage. In polycrystalline nanoparticles, energy dissipation increased with decreasing average grain size, which is attributed to elevated plastic activity induced by the presence of multiple crystallographic orientations. GPA results show that it is possible to discriminate between compositions differing by as little as Δx = 0.1 based on local strain distributions, and the comparison with GPA performed on real STEM micrographs gives a fair agreement. GPA and atomistic stress maps reveal how strain fields evolve during compression and how they correlate with the development of plasticity. These findings highlight the critical role of local structural heterogeneities in dictating the mechanical behavior of nanoscale Pt–Ni systems, and provide strong evidence that GPA can correlate local strain and composition in real high-resolution micrographs.
To investigate the mechanical response and atomic-scale deformation mechanisms of gradient nanostructured FeMnCoCrNi high-entropy alloys under nanoindentation, molecular dynamics simulations were utilized to systematically explore the synergistic regulatory effects of indentation direction, gradient rate, temperature, Fe and Mn concentrations, and indentation velocity on their indentation behavior. The results demonstrate that, at a given gradient rate, both the load and hardness during indentation from the large-grain surface are higher than those from the small-grain surface, which is closely associated with the grain boundary distribution characteristics and dislocation motion behaviors in regions with different grain sizes. When the temperature increases from 300 to 1300 K, high temperature induces the formation and diffusion of disordered structures at grain boundaries. With the decrease in Mn content and the increase in Fe content, the indentation load and hardness of the alloy are significantly enhanced, and the mechanical properties reach a peak when the Mn content is 0% and the Fe content is 40%. This phenomenon is mainly attributed to the disappearance of the softening effect of Mn and the prominent solid-solution strengthening effect of Fe. Under high-speed indentation (100 m/s), the load-displacement curve exhibits a continuous upward trend; in contrast, under low-speed indentation (25 m/s), the curve shows obvious fluctuations. This discrepancy arises from the mismatch between the indentation rate and the evolution rate of the alloy's internal microstructure. In addition, the difference in grain size results in distinct phase transformation and dislocation behaviors: in fine-grain regions, high-density grain boundaries impede dislocation slip and facilitate the formation of dispersed HCP phases, whereas in coarse-grain regions, dislocations can achieve long-range slip, thereby inducing the formation of banded HCP phases. This study clarifies the intrinsic mechanism underlying the multi-factor synergistic regulation of the nanoindentation mechanical behavior of the alloy, providing atomic-scale theoretical support for the design and performance optimization of gradient nanostructured high-entropy alloys.
Nanoscale structures have drawn significant attention due to their unique and interesting properties. At nano size, surface stress and crystal orientation are the key factors in defining the properties. In this context, mechanical properties of an aluminium nanowire, subjected to uniaxial tensile loading have been investigated by utilizing molecular dynamics (MD) simulations. Specifically, under uniaxial tensile loading, the effect of strain rate (0.0005 ps
-1
-0.05 ps
-1
), temperature (10K-800K) and diameter (4nm-6nm) of the NW on several mechanical properties have been examined in the current work. Mechanical properties, like- Young’s modulus, yield stress, yield strain, fracture strain, ductility are obtained from variation of stress with respect to strain analysis. Decrease in Young’s Modulus and increase in yield stress, yield strain, fracture strain, ductility with rise in strain rate are observed. Temperature is found to significantly influence the mechanical characteristics of the nanowire as it affects both the elastic and plastic characteristics. With increase in temperature, Young’s modulus, yield stress, yield strain and fracture strain are found to decrease whereas ductility remained unaffected. On increasing diameter of the NW, the Young’s modulus, yield stress, yield strain showed marginal decrease whereas, fracture strain and ductility increased noticeably. These results show that with rise in strain rate and decrease in temperature/diameter, the strength of aluminium nanowire increases.
S. Barik, Bedamati Majhi, S. S. Sarangi· Journal of Metastable and Na...· 0 citations
4H-SiC substrate is widely employed in semiconductor device fabrication owing to its unique crystal structure and excellent physicochemical properties. However, its deformation behavior during substrate processing remains complex and not fully understood. In this study, molecular dynamics (MD) simulations were performed to systematically investigate the deformation mechanism of single-crystal 4H-SiC during nanoindentation, serving as an atomic-scale analogue of the workpiece–abrasive interaction during substrate processing. Specifically, the relationship between the fluctuations of the load–depth curve and slip were revealed, with particular emphasis on the basal slip (BS) and prismatic slip (PS) behaviors. The results indicate that the fluctuations in the load–depth curve are primarily associated with the nucleation and propagation of dislocations. The initiation of BS is predominantly influenced by the atomic arrangement and stress distribution, while PS initiates at the terminus of BS as the indentation depth increases. Finally, nanoindentation experiments were conducted to validate the reliability of the MD simulations. These findings provide valuable insights into the deformation mechanism and mechanical behavior of 4H-SiC during practical substrate processing.
Wuqing Lin, Hongyang Li, Zhongwei Hu et al.· Materials· 0 citations
Cu/Al laminated composites are promising for lightweight conductive and thermal-management applications, but tensile reliability is strongly affected by deformation incompatibility and damage localization near heterogeneous interfaces. Molecular dynamics simulations were performed to reveal the void-dominated fracture behavior of idealized Cu/Al laminated composites with Cu volume fractions of 15%, 30%, and 50%, in this study. Tensile response and atomistic damage evolution were characterized by stress–strain analysis, polyhedral template matching (PTM), dislocation extraction analysis, local atomic shear strain, and PTM-based root-mean-square deviation (PTM-RMSD). All models exhibit rapid hardening, abrupt post-peak stress release, serrated load-bearing fluctuations, and final through-thickness fracture. As the Cu volume fraction increases from 15% to 50%, the peak stress decreases from approximately 13–11 GPa, while the average post-peak plateau stress decreases from approximately 8.0–6.4 GPa. This inverse trend indicates that the system-level tensile strength is not governed by a simple rule-of-mixtures relationship. Instead, increasing Cu content localizes Shockley partial dislocations, lattice distortion, and high-shear-strain bands. This localization facilitates void nucleation, coalescence, and crack penetration. Interfacial stress analysis further shows that the reduced load-bearing stability of the high-Cu-fraction model is not caused by weakened average interfacial stress continuity, but by localized accommodation of transferred load in defect-rich regions. These results identify plastic localization as the atomistic origin of Cu-fraction-dependent void-dominated fracture.
Wei Feng, Xiaowei Wang, Weiqiang Wan et al.· Engineering Research Express· 0 citations
The deformation behavior of solders based on β-Sn is influenced by a high homologous operating temperature and microstructural heterogeneity. In this study, the deformation mechanisms of single-crystal and polycrystalline Sn were investigated using high-temperature nanoindentation combined with post-indentation microscopy. Constant strain-rate and dynamic mechanical analysis tests were conducted between 30℃ and 180℃ (0.6–0.9 T
m
) to quantify hardness, pop-in, and creep constitutive parameters. Hardness decreases with increasing temperatures (as expected), while pop-in loads shift to lower values at higher temperatures, indicating thermally assisted activation of plastic deformation. Indentations into polycrystalline Sn regions exhibit higher stress exponents (
n
≈ 6.8–7.4) and activation energies at moderate temperatures than indentations in single grains remote from any boundaries, reflecting the influence of grain boundary constraints in accommodating plasticity. At higher temperatures, both microstructures converge toward lower stress exponents and activation energies, suggesting a transition toward deformation mechanisms increasingly governed solely by thermally activated processes. Microstructural characterization reveals slip band formation, dislocation localization, and grain boundary sliding, demonstrating that deformation in polycrystalline Sn at these temperatures results from the combined effects of intragranular dislocation activity and intergranular strain accommodation.
This work employs molecular dynamics simulations to explore how different embedded inclusions (Al, Co, Cr, Fe, and Ni) affect the tensile response and deformation mechanisms of single-crystal Al0.3CoCrFeNi high-entropy alloys. The findings show that inclusion composition has a significant impact on mechanical performance. Among the investigated cases, the specimen containing a Cr inclusion exhibits the highest yield strength and superior resistance to plastic deformation, whereas the Al-inclusion sample shows the lowest mechanical performance. During loading, stress concentration develops around the inclusion-matrix interface, which serves as the primary site for shear-strain localization and dislocation nucleation. As deformation progresses, shear bands propagate diagonally across the specimen, forming approximately 45° to the loading direction. Structural analysis demonstrates that regions adjacent to the inclusions undergo significant atomic rearrangement, including the formation of HCP and amorphous phases from the initial FCC matrix. Furthermore, Cr- and Fe-based BCC inclusions as well as HCP Co inclusions experience partial transformation toward FCC-like configurations because of interfacial interactions with the surrounding alloy matrix. The evolution of dislocations indicates that inclusions act as preferential sources for defect generation, followed by extensive dislocation propagation toward free surfaces under increasing strain.
Thi-Nhai Vu, Van-Trung Pham, T. Nguyen et al.· 2026 11th International Conf...· 0 citations