锆自辐射损伤的分子动力学模拟与缺陷判定研究

Molecular dynamics simulation of self-radiation damages in zirconium and defects identification research

采用分子动力学方法,模拟了300 K温度时由能量10 keV到50 keV的初级反冲原子(primary knock-on atom, PKA)在密排六方(hexagonal close packed, HCP)结构锆晶体内自辐射造成的级联碰撞. 采用离位原子判定法、自间隙原子(self-interstitial atom, SIA)判定法以及Wigner-Seitz(WS)原胞分割法等三种方法对级联碰撞过程中产生的点缺陷进行了判定. 通过对比不同方法获得的点缺陷变化趋势、统计涨落、鲁棒性等特征,发现采用WS分割方法获得的点缺陷数更适合用于描述锆晶体中级联碰撞的辐射损伤. 此外还研究了自间隙原子的基本扩散特征,结果发现其更倾向于一种二维(2D)扩散.

Molecular dynamic simulations were conducted to simulate the collision cascades in HCP zirconium induced by self-recoils in 300 K with primary knock-on atom (PKA) energies setting from 10 keV to 50 keV. Three point defects identification methods, including off-site atoms judgment, SIAs(self-international atom, SIA) determination and WS cell segmentation were used to analyze simulation results. Comparing with the difference of defects evolution, defects statistical fluctuation and robustness of the identification methods, the approach based on the principle of Wigner-Seitz (WS) cell segmentation is considered to be more appropriate in point defects analysis. In addition, the basic diffusion feature of SIA was studied, and the results showed that it is more inclined to a 2D diffusion.