期刊
ACTA MATERIALIA
卷 148, 期 -, 页码 110-122出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2018.01.058
关键词
Grain boundaries; Impurity segregation; Thermodynamic stability; Embrittlement; First-principles calculations
资金
- U.S. Army Research Office [W911NF-16-1-0369]
- National Natural Science Foundation of China [51472188, 51521001]
- Natural Research Funds of Hubei Province [2016CFB583]
- Fundamental Research Funds for the Central Universities in China
- 111 project [B13035]
Impurities are often driven to segregate to grain boundaries, which can significantly alter a material's thermal stability and mechanical behavior. To provide a comprehensive picture of this issue, the influence of a wide variety of common nonmetallic impurities (H, B, C, N, O, Si, P and S) incorporated during service or materials processing are studied using first-principles simulations, with a focus on identifying changes to the energetics and mechanical strength of a Cu Sigma 5 (310) grain boundary. Changes to the grain boundary energy are found to be closely correlated with the covalent radii of the impurities and the volumetric deformations of polyhedra at the interface. The strengthening energies of each impurity are evaluated as a function of covalent radius and electronegativity, followed by first-principles-based tensile tests on selected impurities. The strengthening of a B-doped grain boundary comes from an enhancement of the charge density among the adjacent Cu atoms, which improves the connection between the two grains. Alternatively, the detrimental effect of 0 results from the reduction of interactions between the Cu atoms. This work deepens the understanding of the possible beneficial and harmful effects of impurities on grain boundaries, providing a guide for materials processing studies. (c) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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