The effects of boron and hydrogen on the embrittlement of polycrystalline Ni3Al |
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| Affiliation: | 1. State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi''an Jiaotong University, Xi''an 710049, China;2. Department of Geosciences, Center for Materials by Design, and Institute for Advanced Computational Science, State University of New York, Stony Brook, NY 11794-2100, USA;3. School of Chemical Engineering & Technology, China University of Mining and Technology, Xuzhou 221116, China;4. School of Department of Heat Treatment and Surface Treatment, Avic Aircraft. Co., Ltd. Xi''an Brake Branch, Xingping 713106, China;1. Research Center of Heterogeneous Catalysis and Engineering Sciences, School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou 450001, People''s Republic of China;2. State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People''s Republic of China;3. School of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001, People''s Republic of China |
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| Abstract: | The discrete-variational method within the framework of density functional theory is used to study the effects of both boron and hydrogen on the embrittlement of polycrystalline Ni3Al. The calculated results show that there are strong repulsive interaction between the boron and the hydrogen atoms, if they occupy the nearest interstitial sites, respectively, in the Ni3Al grain boundaries. It indicates that the boron atoms inhibit the diffusion of hydrogen atoms along the grain boundary. It may be the main reason why boron can suppress the moisture induced hydrogen embrittlement. Our results also show that the attractive interactions between boron and some substrate atoms are weakened, but the attractive interactions between boron and other substrate atoms are enhanced, when hydrogen atoms are forced into the grain boundary and occupy the nearest interstitial sites to boron atoms. As a result, the bonding states are polarized in the local region of the grain boundary. It may suppress the movement of slips across the grain boundary. Furthermore, the weakening effects of hydrogen to the grain boundary are hardly affected by the boron atoms, even though they are very near to each other. It can be concluded that hydrogen embrittlement takes place when the boron-doped polycrystalline Ni3Al are charged with hydrogen. |
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