加载速率对单晶γ-TiAl裂纹扩展影响的分子动力学模拟

Molecular Dynamics Simulation for the Effect of Loading Rate on Crack Propagation in Single Crystal γ-TiAl Alloy

运用分子动力学方法研究微观尺度下单晶γ-TiAl裂纹的扩展过程,运用嵌入原子势进行模拟,得到裂纹扩展的轨迹图和能量演变图,比较分析不同加载速率对γ-TiAl能量和应力-应变关系的影响,进而揭示对裂纹扩展的影响。研究表明:随着加载速率的增大,体系的原子运动加剧,总能量上升到峰值的剧烈程度增加,试件断裂的时间缩短,所需的应变越小,而裂纹扩展的形态没有变化;总能量随时间的演化曲线只出现一个峰值。应力-应变曲线中只有弹性阶段,没有塑性阶段,加载速率对拉升过程的弹性变形机理没有影响。

Molecular dynamics simulation was performed to study the crack propagation in single crystalγ-TiAl in the atomic scale level.The atomic trajectory figure as well as energy evolution figure has been obtained by simulation based on EAM.The effect of different loading rate on the energy ofγ-TiAl and stressstrain relation was compared,and the effect of loading rate on crack propagation is revealed.The results indicate that along with the increasing loading rate,atomic motion of the system and total energy curve up to the peak were intensified,the life of specimen to fracture is shortened,the strain decreased,but the form of crack propagation did not change;besides only one wave crest could be discovered in the energy curve.Furthermore,only the elastic stage but no plastic stage could be discovered in stress-strain curve.Loading rate has no effect on elastic deformation mechanism in tensile stage.