A comparative study on shock compression of nanocrystalline Al and Cu: Shock profiles and microscopic views of plasticity
A comparative study on shock compression of nanocrystalline Al and Cu: Shock profiles and microscopic views of plasticity
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DOI：
10.1063/1.4826624
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发表时间：
2013-10
影响因子：
3.2
通讯作者：
Wen-Fei Ma;Wenjun Zhu;Yong Hou
中科院分区：
文献类型：
--
作者：
Wen-Fei Ma;Wenjun Zhu;Yong Hou
用分子动力学模拟方法研究了具有相同晶粒度和织构的纳米金属Al和Cu的冲击压缩行为。结果表明，Al和Cu的冲击前沿可分为三个阶段：弹性阶段、晶界驱动阶段和位错驱动塑性变形阶段。二维冲击响应分析表明，这三个阶段之间的过渡面是非平面的，包括局部应力、剪切、温度和原子构型。冲击铝与铜的不同之处在于，在相同加载条件下，铜的弹性阶段上升率略高于铝，铝的冲击波前宽度比铜宽。在塑性阶段，冲击Al的位错密度低于Cu，晶界塑性对NC Al的冲击前沿和应变的贡献比NC Cu更显著。这些结果通过材料的本征性质和塑性过程的原子学分析得到了解释。在冲击Al样品中，观察到部分位错、完全位错和孪晶，而在冲击铜中几乎没有观察到完美位错和孪晶的证据。
Shock compressions of nanocrystalline (nc) metals Al and Cu with the same grain size and texture are studied by using molecular dynamics simulations. Results have revealed that the shock front of both Al and Cu can be divided into three stages: elastic, grain-boundary-mediated, and dislocation-mediated plastic deformation. The transition planes among these three stages are proven to be non-planar by two-dimensional shock response analysis, including local stress, shear, temperature, and atom configuration. The difference between shocked Al and Cu is that the rise rate of the elastic stage of Cu is slightly higher than that of Al, and that the shock-front width of Al is wider than Cu at the same loading conditions. For the plastic stage, the dislocation density of shocked Al is lower than Cu, and the contribution of grain-boundary-mediated plasticity to shock front and strain for nc Al is more pronounced than for nc Cu. These results are explained through intrinsic material properties and atomistic analysis of the plastic process. In the case of the shocked Al sample, partial dislocations, perfect dislocations, and twins are observed, but few evidence of perfect dislocations and twins are observed in the shocked Cu.