α-Fe裂纹的分子动力学研究

通过分子动力学方法，模拟了α-Fe裂纹的单轴拉伸实验中的形变过程.研究了不同晶体取向裂纹的形变特点和断裂机理，观察到各种形变现象，如位错形核和发射，位错运动，堆垛层错或孪晶的形成，纳米空洞的形成与连接等.计算结果表明，裂纹扩展是塑性过程和弹性过程相结合的过程，其中塑性过程表现为由裂尖发射的位错导致的原子切变行为，而弹性过程的发生则是由无位错区中的原子断键所导致.同时还研究了α-Fe裂纹的形变特点和断裂机理与温度场和应力场的依赖关系.

Molecular dynamics simulation of fracture in α-iron

The deformation process of the crack in α-Fe has been simulated under uniaxial tensile deformation by molecular dynamics (MD) method. The effect of crystal orientations on the deformation mechanisms of the crack has been investigated. Various deformation evidences are clearly observed, such as dislocation nucleation and emission, dislocation movement，stacking faults formation or twinning， and formation and coalescence of voids. The simulated results indicate that the crack propagate by a combination of plastic and elastic processes in which the plastic portion of the crack results from the shear behavior of atoms created by the dislocations that are emitted from the crack tip, and the elastic process occurs as a result of the bond-breaking of the atoms in the dislocation-free zone. It has also been studied the deformation and fracture characteristics of the crack in α-Fe and their dependence on the stress state and the temperature.