Energetics and diffusional properties of He in BCC Mo: An empirical potential for molecular dynamics simulations |
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| Authors: | Yongfeng Zhang Paul C Millett Michael Tonks |
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| Affiliation: | 1. Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433, China;2. Shandong Peninsula Engineering Research Center of Comprehensive Brine Utilization, Weifang University of Science and Technology, Shouguang 262700, Shandong, China;3. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China;1. School of Mechanical Engineering, Hebei University of Technology, Tianjin 300132, China;2. Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology, Tianjin 300132, China;3. School of Physics, Beihang University, Beijing 100191, China;4. Beijing Key Laboratory of Advanced Nuclear Materials & Physics, Beijing 100191, China |
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| Abstract: | This paper presents an interatomic potential for modeling He defects and bubbles in body-centered-cubic (BCC) Mo. We utilize three existing frameworks: the Finnis–Sinclair (FS) potential for Mo–Mo, the Effective-Medium-Theory (EMT) for He–Mo, and the Hartree–Fock-Dispersion (HFD) potential for He–He interactions. The energetics of He defects and the diffusivity of He interstitial given by this potential agree well with ab initio calculations and experimental measurements. Furthermore, in agreement with theoretical prediction, it is shown that the introduction of He gas suppresses the surface diffusivity of BCC Mo, which decays exponentially with increasing He pressure acting on the free surface. The decay constant, correlated with the characteristic interaction volume for He–Mo, is close to the atomic volume of BCC Mo. This suppression effect is important to understand the mobility of small He bubbles. |
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