Vacancy formation enthalpies of high-entropy FeCoCrNi alloy via first-principles calculations and possible implications to its superior radiation tolerance
来源期刊:JOURNAL OF MATERIALS SCIENCE TECHNOLOG2018年第2期
论文作者:Weiliang Chen Xueyong Ding Yuchao Feng Xiongjun Liu Kui Liu Z.P.Lu Dianzhong Li Yiyi Li C.T.Liu Xing-Qiu Chen
文章页码:355 - 364
摘 要:Because atoms in high-entropy alloys(HEAs) coordinate in very different and distorted local environments in the lattice sites, even for the same type of constituent, their point defects could highly vary.Therefore, theoretical determination of the thermodynamic quantities(i.e., defect formation enthalpies)of various point defects is rather challenging because each corresponding thermodynamic quantity of all involve constituents is not unique. The knowledge of these thermodynamic quantities is prerequisite for designing novel HEAs and understanding the mechanical and physical behaviors of HEAs. However,to date there has not been a good method to theoretically derive the defect formation enthalpies of HEAs. Here, using first-principles calculations within the density functional theory(DFT) in combination of special quasi-random structure models(SQSs), we have developed a general method to derive corresponding formation enthalpies of point defects in HEAs, using vacancy formation enthalpies of a four-component equiatomic fcc-type FeCoCrNi HEA as prototypical and benchmark examples. In difference from traditional ordered alloys, the vacancy formation enthalpies of FeCoCrNi HEA vary in a highly wide range from 0.72 to 2.89 eV for Fe, 0.88–2.90 eV for Co, 0.78–3.09 eV for Cr, and 0.91–2.95 eV for Ni due to high-level site-to-site lattice distortions and compositional complexities. On average, the vacancy formation enthalpies of 1.58 eV for Fe, 1.61 eV for Cr, 1.70 eV for Co and 1.89 eV for Ni are all larger than that(1.41 eV) of pure fcc nickel. This fact implies that the vacancies are much more difficult to be created than in nickel, indicating a reasonable agreement with the recent experimental observation that FeCoCrNi exhibits two orders of amplitudes enhancement of radiation tolerance with the suppression of void formation at elevated temperatures than in pure nickel.
Weiliang Chen1,2,Xueyong Ding1,Yuchao Feng2,Xiongjun Liu3,Kui Liu2,Z.P.Lu3,Dianzhong Li2,Yiyi Li2,C.T.Liu4,Xing-Qiu Chen2
1. School of Metallurgy, Northeastern University2. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences3. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing4. Center of Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong
摘 要:Because atoms in high-entropy alloys(HEAs) coordinate in very different and distorted local environments in the lattice sites, even for the same type of constituent, their point defects could highly vary.Therefore, theoretical determination of the thermodynamic quantities(i.e., defect formation enthalpies)of various point defects is rather challenging because each corresponding thermodynamic quantity of all involve constituents is not unique. The knowledge of these thermodynamic quantities is prerequisite for designing novel HEAs and understanding the mechanical and physical behaviors of HEAs. However,to date there has not been a good method to theoretically derive the defect formation enthalpies of HEAs. Here, using first-principles calculations within the density functional theory(DFT) in combination of special quasi-random structure models(SQSs), we have developed a general method to derive corresponding formation enthalpies of point defects in HEAs, using vacancy formation enthalpies of a four-component equiatomic fcc-type FeCoCrNi HEA as prototypical and benchmark examples. In difference from traditional ordered alloys, the vacancy formation enthalpies of FeCoCrNi HEA vary in a highly wide range from 0.72 to 2.89 eV for Fe, 0.88–2.90 eV for Co, 0.78–3.09 eV for Cr, and 0.91–2.95 eV for Ni due to high-level site-to-site lattice distortions and compositional complexities. On average, the vacancy formation enthalpies of 1.58 eV for Fe, 1.61 eV for Cr, 1.70 eV for Co and 1.89 eV for Ni are all larger than that(1.41 eV) of pure fcc nickel. This fact implies that the vacancies are much more difficult to be created than in nickel, indicating a reasonable agreement with the recent experimental observation that FeCoCrNi exhibits two orders of amplitudes enhancement of radiation tolerance with the suppression of void formation at elevated temperatures than in pure nickel.
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