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

Authors :
Longhui Yao
Liang Wang
Xiaojiao Song
Ran Cui
Binqiang Li
Qi Lv
Liangshun Luo
Yanqing Su
Jingjie Guo
Hengzhi Fu
Source :
Materials, Vol 15, Iss 3, p 1190 (2022)
Publication Year :
2022
Publisher :
MDPI AG, 2022.

Abstract

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.

Details

Language :
English
ISSN :
19961944
Volume :
15
Issue :
3
Database :
Directory of Open Access Journals
Journal :
Materials
Publication Type :
Academic Journal
Accession number :
edsdoj.9987e110d00d4202916f0b9343ec8ce4
Document Type :
article
Full Text :
https://doi.org/10.3390/ma15031190