激光温喷丸诱发单晶铜位错扩展的分子动力学模拟

Molecular Dynamics Simulation of Dislocation Development in Monocrystalline Copper induced by Warm Laser Peening

为了研究面心立方金属在热力耦合作用下的微观组织,采用分子动力学方法对激光温喷丸在单晶铜内诱导的位错扩展进行了模拟,并使用中心对称参数研究了变形量对位错扩展的影响规律,以及温度对塑性变形诱导位错扩展的作用,进而从加工硬化的角度分析了其对激光温喷丸强化效果的影响。结果表明,激光温喷丸过程中,塑性变形以"空位簇-不全位错-堆垛层错"的方式诱导产生不全位错与堆垛层错。随塑性变形增加,激光温喷丸的硬化效果逐渐增加。并且,温度可以促进塑性变形过程中位错的形核与扩展,200℃以内,激光温喷丸的硬化效果随温度的增加而增强,温度增至250℃时,硬化效果由于位错湮灭而减弱。

In order to study the microstructure of face center cubic metals induced by thermo-mechanical impact,molecular dynamics method was used to investigate the dislocation evolution of monocrystalline copper treated by warm laser peening（WLP）. The effects of plastic strain on the dislocation development were researched through centrosymmetry parameter. Moreover, the effects of temperature on the dislocation development induced by plastic strain during WLP were also investigated. Finally, the strengthening effects of WLP were analyzed by work hardening. It is shown that partial dislocation and stacking faults are induced by plastic strain in the way of＂vacancy group-partial dislocation-stacking faults＂. As the plastic strain increases, the amount of stacking faults and their stacking extent increases, which leads to a better effect of WLP in work hardening. A higher temperature can promote the nucleation and development of dislocations induced by WLP. The hardening effect of WLP increases with the temperature within 200 ℃, and the hardening effect reduces while it increases to 250 ℃ because of the dislocation annihilation.