Intrinsic brittleness of Mo5SiB2 and alloying effect on ductility studied by first-principles calculations |
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| Affiliation: | 1. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, PR China;2. Henan Engineering Research Center for Wear of Materials, Henan University of Science and Technology, Luoyang 471023, PR China;3. Institute of Applied Physics, University of Science and Technology Beijing, Beijing 100083, PR China;4. Hebei Huabei Diesel Engine Co., Ltd, Shijiazhuang 050081, PR China;1. Chemnitz University of Technology, Chair of Solid Mechanics, Reichenhainer Straße 70, 09126 Chemnitz, Germany;1. Department of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024, China;2. School of Physics and Elecronics, Hunan University, Changsha 410082, China;3. College of Electronmechanical Engineering, Hunan University of Science and Technology, Xiantang 411201, China;1. CNRS, Université de Bordeaux, ICMCB, UPR 9048, 33600 Pessac, France;2. Université Saint Esprit de Kaslik, CSR-USEK, CNRS_L, Jounieh, Lebanon |
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| Abstract: | The ordered intermetallic Mo5SiB2 displays a ceramic-like brittleness at the ambient temperature. The state density, charge distribution and elastic parameters were calculated by first-principles, based on the density functional method. The results indicated that the two different kinds of covalent bonds were intricately woven into the refractory phase. The improved Peierls–Nabarro stress which is caused by this kind of distribution mode makes dislocations move difficultly, resulting in intrinsic brittleness. The effects of substitutional alloying on the ductility of Mo5SiB2 were also assessed by the calculations on the elastic properties and dislocation line energy. It was shown that the metal (Nb, Tc) alloying was not to enhance effectively its toughness, but to improve the brittle-to-ductile transition temperature. |
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| Keywords: | A Molybdenum silicides B Bonding B Brittleness and ductility E Ab-initio calculations |
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