Liu Bin, Yuan Fenglin, Jin Ke, Zhang Yanwen, Weber William J
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA.
J Phys Condens Matter. 2015 Nov 4;27(43):435006. doi: 10.1088/0953-8984/27/43/435006. Epub 2015 Oct 6.
Low-energy recoil events in pure Ni and the equiatomic NiCo alloy are studied using ab initio molecular dynamics simulations. We found that the threshold displacement energies are strongly dependent on orientation and weakly dependent on composition. The minimum threshold displacement energies are along the [1 1 0] direction in both pure Ni and the NiCo alloy. Compared to pure Ni, the threshold displacement energies increase slightly in the NiCo alloy due to the stronger bonds in the alloy, irrespective of the element type of the PKA. A single Ni interstitial occupying the center of a tetrahedron formed by four Ni atoms and a <1 0 0> split interstitial is produced in pure Ni by the recoils, while only the <1 0 0> split interstitial is formed in the NiCo alloy. Compared to the replacement sequences in pure Ni, anti-site defect sequences are observed in the alloy, which have high efficiency for both producing defects and transporting energy outside of the cascade core. These results provide insights into energy transfer processes occurring in equiatomic alloys under irradiation.
利用从头算分子动力学模拟研究了纯镍和等原子比镍钴合金中的低能反冲事件。我们发现，阈值位移能强烈依赖于取向，而对成分的依赖较弱。纯镍和镍钴合金中最小的阈值位移能都沿[1 1 0]方向。与纯镍相比，由于合金中键更强，镍钴合金中的阈值位移能略有增加，而与初级撞出原子（PKA）的元素类型无关。反冲在纯镍中产生了一个占据由四个镍原子形成的四面体中心的单个镍间隙原子和一个<1 0 0>分裂间隙原子，而在镍钴合金中只形成了<1 0 0>分裂间隙原子。与纯镍中的置换序列相比，在合金中观察到了反位缺陷序列，其在产生缺陷和将能量传输出级联核心方面都具有高效率。这些结果为辐照下等原子合金中发生的能量转移过程提供了见解。
