Microstructure Evolution and Toughening Mechanism of a Nb-18Si-5HfC Eutectic Alloy Created by Selective Laser Melting

Autor: Longhui Yao, Liang Wang, Xiaojiao Song, Ran Cui, Binqiang Li, Qi Lv, Liangshun Luo, Yanqing Su, Jingjie Guo, Hengzhi Fu
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Materials, Vol 15, Iss 3, p 1190 (2022)
Druh dokumentu: article
ISSN: 1996-1944
DOI: 10.3390/ma15031190
Popis: Because of their superior mechanical performance at ultra-high temperatures, refractory niobium–silicon-based alloys are attractive high-temperature structural alloys, particularly as structural components in gas turbine engines. However, the development of niobium–silicon-based alloys for applications is limited because of the trade-off between room temperature fracture toughness and high-temperature strength. Here, we report on the fabrication of a Nb-18Si alloy with dispersion of hafnium carbide (HfC) particles through selective laser melting (SLM). XRD and SEM-BSE were used to examine the effects of scanning speed on the microstructure and the phase structure of the deposited Nb-18Si-5HfC alloy. The results show that when the scanning speed rises, the solid solubility of the solid solution improves, the interlamellar spacing of eutectics slowly decrease into nano-scale magnitude, and the corresponding hafnium carbide distribution becomes more uniform. We also discover the hafnium carbide particles dispersion in the inter-lamella structure, which contributes to its high fracture toughness property of 20.7 MPa∙m1/2 at room temperature. Hardness and fracture toughness are simultaneously improved because of the control of microstructure morphology and carbide distribution.
Databáze: Directory of Open Access Journals
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