沿〈111〉晶向冲击加载下铜中纳米孔洞增长的塑性机制研究

 用分子动力学方法计算模拟了沿〈111〉晶向冲击加载过程中，单晶铜中纳米孔洞（直径约1.3 nm）的演化及其周围区域发生塑性变形的过程。模拟结果表明，在沿〈111〉晶向冲击加载后，在面心立方（fcc）结构中的4族{111}晶面中有3族发生了滑移。伴随孔洞的增长，在所激活的3族{111}晶面上，观察到位错在孔洞表面附近区域成核，然后向外滑移，其中在剪切应力最大的〈112〉方向上，其位错速度超过横波声速，其它〈112〉方向的位错速度低于横波声速。模拟得到的位错阻尼系数范围与实验值基本符合。由于孔洞周围产生的滑移在空间比较对称，孔洞增长形貌接近球形。在恒定的冲击强度下，孔洞半径增长速率近似保持恒定，其速率随着冲击强度的增加而增大。

Plasticity Mechanism Associated with Nano-Void Growth under Impact Loading along <111> Direction in Copper

Evolution of Nano-void (diameter d≈1.3 nm) in single crystal copper and associated plasticity deformation around the nano-void under impact loading are investigated by means of molecular dynamics (MD) simulation. The results of simulation reveal that in the tensile process there are three of all four {111} family planes to be activated to glide, dislocations are nucleated in the region near the void surface and then move outside on three {111} family planes as the void grows. The velocity of dislocation along 〈112〉 directions with the maximum resolve shear stress can exceed transverse sound velocity. The calculated dislocation damping constant is appropriately consistent with the experiment results. Due to the approximately symmetrical plastic deformation around the void, the shape of the void during growth process is almost spherical. The growth rate of the void radius is observed to be constant under constant shock strength, and the amplitude increases as well as the shock strength increases.