体心立方金属反常滑移及其微观机制的系统研究

The <111>/2 screw dislocations dominate the low-temperature plastic deformations of body-centered cubic metals. Atomistic modeling is a powerful tool to capture their behaviors, but its predictions cannot account for anomalous slip that violates the Schmid law and its underlying mechanism because the interaction and reaction between dislocations are ignored. In this research project about anomalous slip in body-centered cubic metals, our main efforts will focus on the following aspects: (1) to give the variation of yield stress of anomalous slip and primary slip with the loading axis in a quantitative way at different temperatures and strain rates, and then to propose a criterion of the onset of anomalous slip, (2) to simulate the interaction and reaction between two sets of screw dislocations with different Burgers vectors , to trace the variation of core structures and kink formation to uncover the underlying mechanism of anomalous slip, and (3) to properly analyze the experimental data of anomalous slip.

体心立方金属中<111>/2螺位错主导材料塑性变形过程。原子尺度模拟计算是定量描述这些位错最有效的工具，但是仍然无法解释反常滑移这种完全违反Schmid定律的塑性变形行为及其微观机制。这主要是由于前人的模拟计算主要研究单一螺位错的性能，而忽略了位错交互作用和反应（生成六边形位错网）。本项目将利用原子尺度模拟计算系统研究反常滑移现象，主要完成以下内容：（1）在一定温度和应变速率下，模拟计算单一位错和六边形位错网的屈服准则，定量预测反常滑移出现的条件，用于解释伴随反常滑移的实验现象；（2）动态揭示两列不同Burgers矢量螺位错间的交互作用和反应，重点关注在位错近距离作用或反应时位错核结构的变化和扭折形成机制，开辟理解体心立方金属塑性变形的正确路径；（3）纠正前人实验数据分析中的偏差和谬误。