金属Mo中韧位错运动特性的分子动力学研究
Dynamics characteristics of edge dislocation in Mo by molecular dynamics
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摘要: 通过分子动力学方法(MDM), 采用镶嵌原子势法(EAM), 沿[111]方向插入两层(211)半原子面形成位错，模拟了低温不同冲击载荷下和相同载荷不同温度下金属Mo中韧位错的动力学特性. 结果表明：在低温冲击载荷下，Mo中的韧位错可以由静止加速到超过波速. 随着载荷的增加，在位错运动的[111]方向将会出现3个波速；在相同载荷不同温度下，位错的速度随着温度的升高而减小，即影响位错速度的拖动系数$B(T)$随温度升高而增大. 随着冲击载荷的增大，拖动系数随温度的变化趋势减缓，即外加载荷对B(T)也有影响.Abstract: This investigation simulates the dynamics characteristics of edge dislocation in BCC crystal Mo under different temperature and abrupt shear strains by molecular dynamics (MD) simulation. Results show a decrease of mobility with increasing temperature, namely the drag force increased with increasing temperature and decrease with increasing loading. A stationary dislocation can surmount the wave velocity under an abrupt shear strain in crystal Mo in this simulation. Results indicate that there are three wave speeds in the [111] direction in which the dislocation moved. The movement of the edge dislocation when it surmounts the transverse wave speed and drops to subsonic is pictured.
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