期刊
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
卷 103, 期 5, 页码 3311-3320出版社
WILEY
DOI: 10.1111/jace.17018
关键词
first-principles; grain boundary; segregation; strength; TiB2
资金
- National Natural Science Foundation of China [51672064, 51972089, U1435206]
TiB2 exhibits a unique combination of excellent properties that make it promising candidate for applications in extreme environments, where retention of strength at high temperatures is essential. Tailoring grain boundary properties by segregation is believed a prominent way to design high-temperature performance of ceramics. In this work, segregation tendencies of solute elements, including Sc, Y, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, in TiB2 grain boundaries and the strengthening/weakening effects induced by segregations are investigated by first-principles calculations. The results reveal that small atoms tend to segregate to grain boundary sites with local compression strains, while large atoms prefer grain boundary sites with local expansion strains. Deteriorated grain boundary strength is usually caused by additional expansion strain induced by segregation, while improved grain boundary strength results from either enhanced local bonding induced by segregation of small atoms or increased fracture strain due to segregation of large atoms. Cr and V, especially Cr, exhibit strong segregation tendency and improvement on grain boundary strength, which provides useful guidelines for the design of high performance TiB2-based materials.
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