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利用分子动力学方法研究了不同晶粒度的纳米多晶铁在冲击压缩下的结构相变过程,模拟结果表明:纳米多晶铁的冲击结构相变(由体心立方(bcc)结构α相到六角密排(hcp)结构ε相)发生的临界冲击应力在15GPa左右.纳米多晶铁在经过弹性压缩变形后,晶界导致的塑性变形开始发生,然后大多数相变从晶界成核并最终发展为大规模相变.不同变形过程在应力和粒子速度剖面上能得到清晰的体现,并通过微观原子结构分析分辨.冲击压缩后的微观结构以晶界原子和以fcc结构原子充当孪晶界的hcp原子为主.晶粒度明显影响晶界变形及相变原子比例,从而影响冲击波阵面的结构,并初步分析了影响原因.
The phase transformation process of nanocrystalline polycrystalline iron with different grain size under impact compression was studied by molecular dynamics method. The simulation results show that the impact phase transition of nanocrystalline polycrystalline iron (bcc structure α phase To hexagonal close-packed (hcp) structure ε) occurs at a critical impact stress of about 15 GPa. After the elastic deformation of nano-polycrystalline iron, the plastic deformation caused by the grain boundary begins to occur, and then most of the phase transition occurs from the grain boundary And finally developed into a large-scale phase change.Different deformation process in the stress and particle velocity profiles can be clearly reflected, and through the analysis of microscopic atomic structure analysis.After impact compression of the microstructure with grain boundary atoms and fcc structure atoms act as a twin Grain boundary hcp atomic dominated grain size significantly affect the grain boundary deformation and phase transformation atomic ratio, thus affecting the structure of the shock wave front, and the initial analysis of the causes.