Abstract We perform molecular dynamics simulations to explore the effects of grain size, alloy composition, and temperature on the mechanical characteristics of Si100-xGex alloys during the indentation process. The structural evolution, von Mises shear strain, von Mises stress, and dislocation in workpiece are evaluated to explain the transformation of the loading force. Moreover, hardness and Young's modulus are also computed to evaluate the mechanical characteristics of different specimens. The results present that the loading force, hardness, Young's modulus of single crystalline are higher than polycrystalline. Besides, the loading force and hardness reduce as the grain size reduces; this result reveals a reverse Hall-Petch relation. In the indentation process of small grain size workpiece, the dislocation freely migrates to the grain boundary and absorbed, leading the amount of dislocation movement significantly reduces, which will instead promote the migration and sliding at the grain boundaries. It is confirmed that the grain boundaries play an essential role in the deformation behavior of the material. For the purpose of study the effect of various alloy compositions on the mechanical characteristics of the Si100-xGex substrate, a series of various alloy compositions are conducted: Si20Ge80, Si40Ge60, Si50Ge50, Si60Ge40, and Si80Ge20. The results reveal that the hardness, and Young's modulus of specimens increase as the Si content increases. In addition, the influence of temperature is also investigated in this work. It is found that when the temperature increases, leading to the atomic displacement and shear strain increase, the total dislocation length and the number of defect atoms increase, which leads to the hardness and Young's modulus reduction.

中文翻译：

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压痕过程中晶粒尺寸、合金成分和温度对 Si100-xGex 合金力学特性的影响

摘要 我们进行了分子动力学模拟，以探索在压痕过程中晶粒尺寸、合金成分和温度对 Si100-xGex 合金机械特性的影响。评估工件中的结构演化、von Mises 剪切应变、von Mises 应力和位错，以解释加载力的转变。此外，还计算硬度和杨氏模量以评估不同试样的机械特性。结果表明，单晶的加载力、硬度、杨氏模量均高于多晶。此外，加载力和硬度随着晶粒尺寸的减小而降低；该结果揭示了反向霍尔-佩奇关系。在小晶粒尺寸工件的压痕过程中，位错自由迁移到晶界并被吸收，导致位错运动量显着减少，反而会促进晶界处的迁移和滑动。已经证实，晶界在材料的变形行为中起着至关重要的作用。为了研究各种合金成分对Si100-xGex衬底机械特性的影响，进行了一系列各种合金成分：Si20Ge80、Si40Ge60、Si50Ge50、Si60Ge40和Si80Ge20。结果表明，试样的硬度和杨氏模量随着 Si 含量的增加而增加。此外，本文还研究了温度的影响。发现当温度升高时，导致原子位移和剪切应变增大，