Energetics and electronic structure of grain boundaries and surfaces of B- and H-doped Ni3Al

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	Energetics and electronic structure of grain boundaries and surfaces of B- and H-doped Ni3Al
	Q. M. Hu; R. Yang; D. S. Xu; Y. L. Hao; D. Li; W. T. Wu
	2003
发表期刊	Physical Review B
ISSN	1098-0121
卷号	67 期号:22
摘要	By using a first-principles plane-wave pseudopotential method, the energetics and electronic structure of Sigma5(210) grain boundary (GB) and the (210) surface of undoped as well as B- and/or H-doped Ni3Al are investigated. The geometric structures of the GBs and surfaces are fully relaxed by minimizing the total energy and interatomic force. The results show that B induces a large lattice expansion but H does not. Both B and H "prefer" to occupy the Ni-rich hole at the GB or surface but not the Ni-deficient one. The segregation energies of B and H as well as the interaction energy between them at the GB and surface are calculated. The calculation indicates that B segregates more strongly to the GB than to the surface, which results in an increase in the Griffith work of the GB and, therefore, in agreement with the experiments, improves the ductility of Ni3Al. Contrary to the case of B, H segregates more strongly to the surface than to the GB, which results in a decrease in Griffith work and confirms H as an embrittler for Ni3Al. The calculation of the interaction energy between B and H demonstrates that B and H repel each other. Consequently, B may block the site of occupation of H at the GB, and restrain the H-induced embrittlement. To understand the mechanism of the obtained energetic features, the electronic densities of states (DOSs) are calculated. A comparison of the total DOSs between the B-doped GB and undoped as well as H-doped ones shows that B increases the hybridization of the GB, which contributes to the enhanced binding of the B-doped GB over the undoped and H-doped ones. When the site of B changes from bulk to GB to surface, the hybridization between B and Ni decreases accordingly. It is proposed that the segregation behavior of B at the GB and surface is dominated by the competition between B(p)-Ni(d) bond energy and the strain energy induced by B. The preference of B for the Ni-rich interstice in Ni3Al is explained by the repulsive interaction between B and Al atoms resulting from the hybridization between their electrons when they are close to each other. The repulsion between B and H can also be explained by the same electronic structure mechanism as that for the B-Al interaction. The segregation of B at surface shifts the DOS of its nearest neighbor Ni to lower energy. This may increase the chemisorption potential energy of H2O on Ni3Al surface and, therefore, decrease the reactivity of the surface, inhibiting the environmental embrittlement of Ni3Al.
部门归属	chinese acad sci, inst met res, titanium alloy lab, shenyang 110016, peoples r china. chinese acad sci, inst met res, state key lab corros & protect, shenyang 110016, peoples r china.;hu, qm (reprint author), chinese acad sci, inst met res, titanium alloy lab, 72 wenhua rd, shenyang 110016, peoples r china
关键词	Intergranular Fracture Environmental Embrittlement Polycrystalline Ni3al Water Dissociation First-principles Metal-surfaces Boron Segregation Ductility Hydrogen
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WOS记录号	WOS:000184011600027
引用统计	被引频次：53[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/35855
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	Q. M. Hu,R. Yang,D. S. Xu,et al. Energetics and electronic structure of grain boundaries and surfaces of B- and H-doped Ni3Al[J]. Physical Review B,2003,67(22).
APA	Q. M. Hu,R. Yang,D. S. Xu,Y. L. Hao,D. Li,&W. T. Wu.(2003).Energetics and electronic structure of grain boundaries and surfaces of B- and H-doped Ni3Al.Physical Review B,67(22).
MLA	Q. M. Hu,et al."Energetics and electronic structure of grain boundaries and surfaces of B- and H-doped Ni3Al".Physical Review B 67.22(2003).