The importance of taking into account directional solidification of grains formed during 3D printing is determined by a substantial influence of their crystallographic orientation on the mechanical properties of a loaded material. This issue is studied in the present study using molecular dynamics simulations. The compression of an FCC single crystal of aluminum bronze was performed along the <111> axis. A Ni single crystal, which is characterized by higher stacking fault energy (SFE) than aluminum bronze, was also considered. It was found that the first dislocations started to move earlier in the material with lower SFE, in which the slip of two Shockley partials was observed. In the case of the material with higher SFE, the slip of a full dislocation occurred via successive splitting of its segments into partial dislocations. Regardless of the SFE value, the deformation was primarily occurred by means of the formation of dislocation complexes involved stair-rod dislocations and partial dislocations on adjacent slip planes. Hardening and softening segments of the calculated stress–strain curve were shown to correspond to the periods of hindering of dislocations at dislocation pileups and dislocation movement between them. The simulation results well agree with the experimental findings.

中文翻译：

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增材制造<111> FCC CuAl单晶变形的数值研究与实验验证

考虑到3D打印过程中形成的晶粒的定向凝固的重要性，取决于晶粒的晶体取向对负载材料的机械性能的重大影响。在本研究中使用分子动力学模拟研究了这个问题。沿着<111>轴执行铝青铜的FCC单晶的压缩。还考虑了一种镍单晶，其特征在于比铝青铜具有更高的堆垛层错能（SFE）。发现在具有较低SFE的材料中，第一个位错开始较早地运动，在该运动中观察到两个Shockley分部的滑移。对于具有较高SFE的材料，完全位错的滑动是通过将其片段连续拆分为部分位错而发生的。无论SFE值如何，变形主要是通过位错复合体的形成而发生的，该位错复合体包括阶梯状位错和相邻滑移面上的部分位错。计算出的应力-应变曲线的硬化和软化段表明与位错堆积处的位错受阻的时间以及位错之间的位错运动相对应。仿真结果与实验结果吻合良好。