Xu Q, Guan H Q, Zhong Z H, Huang S S, Zhao J J
Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, 590-0494, Japan.
Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian, 116024, China.
Sci Rep. 2021 Jan 12;11(1):608. doi: 10.1038/s41598-020-79775-0.
When face-centered cubic (FCC) metals and alloys with low stacking fault energy (SFE) are irradiated by high-energy particles or deformed at high speed, stacking fault tetrahedra (SFTs), which are a type of vacancy cluster defect, are often formed. Therefore, SFTs were expected to form in the CoCrFeMnNi equiatomic high-entropy alloy (HEA). However, no SFT was observed in the CoCrFeMnNi HEA with high-speed plastic deformation even after annealing at 873 K. To elucidate this mechanism, the binding energy of vacancy clusters in the CoCrFeMnNi HEA was calculated based on first principles. The binding energy of the di-vacancy cluster was positive (average of 0.25 eV), while that of the tri-vacancy cluster was negative (average of - 0.44 eV), suggesting that the possibility of formation of a tri-vacancy cluster was low. The inability to form a cluster containing three vacancies is attributed to the excellent irradiation resistance of the CoCrFeMnNi HEA. However, if an extra vacancy is added to a tri-vacancy cluster (with negative binding energy), the binding energy of the subsequent tetra-vacancy cluster may become positive. This suggests that it is possible to form vacancy clusters in the CoCrFeMnNi HEA when high-energy ion or neutron irradiation causes cascade damage.
当具有低堆垛层错能（SFE）的面心立方（FCC）金属和合金受到高能粒子辐照或高速变形时，常常会形成一种空位团簇缺陷——堆垛层错四面体（SFTs）。因此，预计在CoCrFeMnNi等原子高熵合金（HEA）中会形成SFTs。然而，即使在873 K退火后，在经历高速塑性变形的CoCrFeMnNi HEA中也未观察到SFTs。为了阐明这一机制，基于第一性原理计算了CoCrFeMnNi HEA中空位团簇的结合能。双空位团簇的结合能为正（平均0.25 eV），而三空位团簇的结合能为负（平均-0.44 eV），这表明形成三空位团簇的可能性较低。无法形成包含三个空位的团簇归因于CoCrFeMnNi HEA具有优异的抗辐照性能。然而，如果向具有负结合能的三空位团簇中添加一个额外的空位，随后的四空位团簇的结合能可能会变为正。这表明当高能离子或中子辐照导致级联损伤时，在CoCrFeMnNi HEA中有可能形成空位团簇。
