고엔트로피 합금강의 시효경화 및 재결정 연화현상

• Published in: 대한금속·재료학회지, 55(10) Vol. 55; no. 10; pp. 684 - 689
• Main Authors: 최병학, Byung Hak Choe, 장현수, Hyeon Su Jang, 김형섭, Hyoung Seop Kim, 문종언, Jong Un Moon
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 05.10.2017; 대한금속·재료학회
• Subjects: age hardening; annealed softening; Cr 23 C 6 carbide; high entropy alloy; nano-grain; nano-twin; TEM microstructure; 재료공학
• ISSN: 1738-8228; 2288-8241
• DOI: 10.3365/KJMM.2017.55.10.684

Age hardening and re-crystallization softening of a type of high entropy alloy, CoCrFeMnNi, was performed to investigate the relationship between microstructure and the property of mechanical hardness. Equiatomic CoCrFeMnNi was produced by casting followed by homogenizing, cold rolling and post heat treatments. TEM analysis revealed that the microstructure of the as-rolled alloy was composed of elongated grains with twin laths and a shear band with fine grains, which exhibited a hardness of 371 HV. Following a 500 ℃ heat treatment the microstructure was composed of nano-twins and nano-grains, which represented age hardening, with 454 HV hardness. The microstructure of 700 ℃ heat treated samples was composed of re-crystallized grains and annealing twins, which represented annealed softening, with 244 HV hardness. The 700 ℃ heat treatment also produced spherical particles of 0.1 m maximum grain size, identified as Cr 23 C 6 type carbide. †(Received March 13, 2017; Accepted May 22, 2017)