应变速率对含空洞的镁孪晶界面塑性变形机制的影响

利用嵌入原子势的分子动力学模拟,研究了应变速率对含空洞的镁孪晶界面塑性变形机制的影响。结果表明,塑性变形的主要形式包括不全位错、滑移带和堆垛层错;应变速率不会改变试样的杨氏模量,应变速率愈大屈服应力愈大;随着应变速率增大,位错和滑移带的数量增加,堆垛层错的数目先增加后减小,位错运动自由行程的平均长度减小;随着变形进行,位错源不断产生新位错,导致位错密度提高;高应变速率时,晶界处容易形成应力集中,并会有微裂纹产生。

Effects of Strain Rate on Plastic Deformation Mechanism of Void in Magnesium Twin Interface

The effects of strain rate on the plastic deformation mechanism of magnesium twin interface with void were investigated by molecular dynamics simulation with embedded atomic potential.The results reveal that the main forms of plastic deformation include partial dislocation,slip band and stacking fault.The Young’s modulus is independent of strain rate,and with the increase of the strain rate,the yield stress is increased.With the strain rate increase,the number of dislocations and slip bands are increased,while the number of stacking faults is increased firstly and then decreased,meanwhile the average length of dislocation motion free travel is decreased.With the deformation applied,the dislocation source produces new dislocations continuously,which leads to the increase of dislocation density.With high strain rate,stress concentration is easy to form at grain boundary,and microcracks will occur.