Cu-Ni binary alloy has become the attention of scientific world for its potentials in nanodevices. It is indispensable to investigate on the mechanical properties of this material due to lack of previous work done regarding this binary alloy. Molecular dynamics (MD) studies were performed on nanopillar (NP) structures comprised of Cu-Ni binary alloy having an FCC unit cell with Cu atoms selectively replaced by Ni atoms. This selective replacement resulted in a better stress behavior than the randomly replaced alloy structure when both tension and compression load were applied. The effect of crystal orientation, NP dimensions, temperature, and strain rate on the stress–strain curve of Cu-Ni binary alloy NPs was thoroughly investigated under tensile loading. This investigation reveals significant influence of crystal orientation on ultimate strength and flow stress region. Among four different crystal orientations, <111> orientation shows maximum strength behavior under tensile loading, while <110> shows highest strength under compressive load. However, in both cases, i.e. tension and compression, the poorest stress behavior was observed for <001> orientation. Under tensile load, <111>-oriented binary alloy fails due to the formation of Shockley partials followed by formation of complex dislocation network. On the other hand, <110>-oriented binary alloy fails due to the formation of Lomer–Cottrell (LC) lock from the Shockley partials. Total dislocation length is calculated, and its effect on the stress–strain behavior of the Cu-Ni binary alloy is discussed. Highest Young’s modulus and yield stress are observed on <111>-oriented binary alloy among other orientations, and these values for <111>-oriented NP was found to decrease with the increment of temperature. If the temperature is increased, yield stress and Young’s modulus decrease. The effect of cross section width was also investigated in this study, and it was found that yield stress decreases with the increment of cross section width due to the effect of surface atom fraction. Increasing the strain rate causes the initiation of amorphous structure, resulting in superplastic behavior of the <111>-oriented Cu-Ni binary alloy NP.

中文翻译：

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Cu-Ni二元合金纳米柱的力学行为研究：分子动力学研究。

Cu-Ni二元合金因其在纳米器件中的潜力而备受科学界的关注。由于缺乏有关这种二元合金的先前工作，因此必须研究这种材料的机械性能。对纳米柱（NP）结构进行了分子动力学（MD）研究，该结构由具有FCC晶胞且Cu原子选择性地被Ni原子取代的Cu-Ni二元合金组成。当同时施加拉力和压缩载荷时，这种选择性置换比随机置换的合金结构产生更好的应力行为。在拉伸载荷下，研究了晶体取向，NP尺寸，温度和应变速率对Cu-Ni二元合金NPs应力-应变曲线的影响。这项研究揭示了晶体取向对极限强度和流动应力区域的显着影响。在四种不同的晶体取向中，<111>取向在拉伸载荷下表现出最大的强度行为，而<110>在压缩载荷下表现出最高的强度。但是，在两种情况下（即拉伸和压缩），对于<001>方向，观察到的应力行为最差。在拉伸载荷下，<111>取向的二元合金由于形成了Shockley部分而随后形成了复杂的位错网络而失效。另一方面，<110>取向的二元合金由于在肖克利零件中形成了Lomer–Cottrell（LC）锁而失效。计算了总位错长度，并讨论了其对Cu-Ni二元合金的应力-应变行为的影响。在其他取向中，在<111>取向的二元合金中观察到最高的杨氏模量和屈服应力，并且发现<111>取向的NP的这些值随温度的升高而降低。如果温度升高，则屈服应力和杨氏模量降低。在这项研究中还研究了横截面宽度的影响，发现由于表面原子分数的影响，屈服应力随着横截面宽度的增加而减小。应变速率的增加导致非晶结构的开始，导致<111>取向的Cu-Ni二元合金NP的超塑性行为。如果温度升高，则屈服应力和杨氏模量降低。在这项研究中还研究了横截面宽度的影响，发现由于表面原子分数的影响，屈服应力随着横截面宽度的增加而减小。应变速率的增加导致非晶结构的开始，导致<111>取向的Cu-Ni二元合金NP的超塑性行为。如果温度升高，则屈服应力和杨氏模量降低。在这项研究中还研究了横截面宽度的影响，发现由于表面原子分数的影响，屈服应力随着横截面宽度的增加而减小。应变速率的增加导致非晶结构的开始，导致<111>取向的Cu-Ni二元合金NP的超塑性行为。