温度对金属材料钼位错发射的影响

应用关联参照模型、随位错位置变化的柔性位移边界条件和三维分子动力学方法研究了体心立方（ＢＣＣ）金属晶体钼在不同温度下裂尖发射位错的力学行为，随着温度的提高，不但发射位错的临界应力强度因子下降而且在同一应 度因子条件下，发射位错的数量出增加，位错速度和不全位错之间的扩展距离对温度不敏感，在位错发射过程中，发现了稳定的和不稳定的两个变形状态，在稳定的有状态，位错发射后，塞积在远离裂纹尖端处；必须增加外

THE EFFECT OF TEMPERATURE ON DISLOCATION EMISSION FOR THE METAL MATERIAL Mo

For the metal material Mo, the effect of thermally activated energy on the dislocation emission from a crack tip is simulated. The simulation is based on the correlative reference model on which the flexible displacement boundary scheme is introduced naturally. The simulation shows that as temperature increases the critical stress intensity factor for the first dislocation emission will decrease and the total number of emitted dislocations increase for the same external loading condition. The dislocation velocity and the extensive distance among the emitted partial dislocations are not sensitive to the temperature. In the process of dislocation emission, two different deformation states are observed. They are the stable and unstable deformation states respectively. In the stable deformation state, the nucleated dislocation will emit from the crack tip and piles up at a distance far away the crack tip, after that the new dislocation can not be nucleated unless the external loading increases. In the unstable deformation state, a number of dislocations can be emitted from the crack tip continuously under the same external load.