【摘要】 通过分子动力学方法模拟了三维α-FeⅠ型裂纹的单向拉伸实验中的裂纹扩展过程.研究了在不同温度下裂纹扩展时位错的形成过程和断裂机理.计算结果表明,裂纹扩展过程是位错不断发射的过程.裂纹尖端附近先形成无位错区和层错,当裂纹处应力增加到K₁=0.566 MPam^1/2时,裂纹尖端附近的某一层原子会逐渐分叉形成两层原子,分层后的原子层继续分离形成位错;当应力K_I达到0.669 MPam^1/2时第一个位错发射.随着温度的升高,临界应力强度因子逐渐降低,同时位错发射也相应地加快.更多还原

【Abstract】 The process of I-mode crack propagations in crFe for uniaxial tension experiments are simulated by molecular dynamics（MD） methods.The formation process of dislocation and fracture mechanisms in the crack growing under various temperatures were studied.The results show that the crack propagation is a process of successive emission of dislocation.The dislocation-free zone and the stacking faults were initially formed at crack tip.When the stress K_I increased into 0.566 MPam^1/2,one layer of atoms near crack tip would be separated into two layers which produced a dislocation.The first dislocation was emitted when stress K_I reached 0.669 MPam^1/2.With the temperature increasing,the critical stress intensity factor decreased gradually and the dislocation emission correspondingly became faster as well.更多还原