期刊
CERAMICS INTERNATIONAL
卷 47, 期 6, 页码 7511-7520出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2020.11.090
关键词
Transition-metal aluminium nitrides; First-principles; Mechanical properties; Ideal strength; Electronic structure
资金
- National Natural Science Foundation of China [51572219, 51872227, 11964026]
- Natural Science Basic Research Plan in the Shaanxi Province of China [2020JM-621, 2020JQ-892]
- Natural Science Foundation of the Education Committee of Shaanxi Province of China [18JK0050, 20JK0488]
- Natural Science Foundation of Inner Mongolia [2019MS01010]
- Scientific Research Projects in Colleges and Universities in Inner Mongolia [NJZZ19145]
Transition-metal aluminium nitrides, widely used as protective coatings, have been found to exhibit superior mechanical properties in the hexagonal phase V0.5Al0.5N compared to the metastable cubic phase. The mechanical enhancement is attributed to the metallic-to-semiconductor transition and the strengthening of bonds between metal elements and N atoms in the hexagonal phase.
Transition-metal aluminium nitrides widely used as protective tool coatings are a class of materials with a combination of high hardness, outstanding wear resistance as well as good chemical stability. In this work, through a well developed structure searching method, the ground-state phase of V0.5Al0.5N is verified and systematically studied on its mechanical and electronic properties by comparing with Ti0.5Al0.5N and W0.5Al0.5N via first-principles calculations. Our results show that the ground-state phase of V0.5Al0.5N adopts a hexagonal structure of P6(3)/mmc symmetry. Mechanical property studies demonstrate the hexagonal phase has a surprisingly improved hardness of about 38 GPa and enhanced ideal strengths relative to its well-known metastable cubic B1 phase whose hardness is only about 20 GPa. This mechanical enhancement greatly expands the upper limit of the strength and hardness for this type of Al-containing ternary systems. Meanwhile, detailed analysis on strength and elastic anisotropy indicates it also exhibits much better mechanical isotropy. Underlying mechanism of the mechanical enhancement is explored by the electronic analysis in-depth. The position of the E-F is tuned by the introduction of the Al element and this electronic tuning leads to a metallic-to-semiconductor transformation from B1 to the hexagonal phase and the strengthening of the bonds between the metal elements and the N atoms.
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