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激光冲击强化利用激光冲击波力学效应可提高金属材料力学性能,现有实验手段难以测量波后动态物理参量、局部动态力学量以及微观组织动态运动过程。采用分子动力学方法,在300K初始温度下对纯钛进行冲击模拟,观察到冲击加载下冲击波在纯钛中传播的动态双波结构,得到了加载过程中的力学量动态变化以及力学作用下孪晶的动态生长过程。塑性变形过程中,由于位错的塞积和释放,正应力上升的同时剪切力和流变应力不断下降,形成平行孪晶栅。在受冲击表面观察到了极薄的非晶层,其形成与超高应变率塑性变形和动态再结晶相关,且孪晶和非晶层结构均与透射电子显微镜结果吻合较好。
Laser shock strengthening can improve the mechanical properties of metallic materials by using the laser shock wave mechanical effect. It is difficult to measure the dynamic physical parameters of waves, the local dynamic mechanics quantities and the microscopic dynamic process by the existing experimental methods. The dynamic simulation of pure titanium at 300K initial temperature was carried out by using molecular dynamics method. The dynamic double-wave structure of shock wave propagating in pure titanium under shock loading was observed. The dynamic changes of mechanical quantities during loading and twins Crystal dynamic growth process. During plastic deformation, due to the plugging and release of dislocations, the normal stress increases while the shear stress and the flow stress continue to decrease, forming a parallel twin gate. An extremely thin amorphous layer was observed on the impacted surface, and its formation was related to the ultrahigh strain rate plastic deformation and dynamic recrystallization. Both the twinned and amorphous layer structures were in good agreement with those of transmission electron microscopy.