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.