Strengthening CoCrFeNi high-entropy alloy by Laves and boride phases

• Published in: China foundry Vol. 19; no. 6; pp. 457 - 463
• Main Authors: Chen, Xiu-gang, Qin, Gang, Gao, Xue-feng, Chen, Rui-run, Song, Qiang, Cui, Hong-zhi
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.11.2022; School of Materials Science and Engineering,Shandong University of Science and Technology,Qingdao 266500,China%School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China%School of Materials Science and Engineering,Shandong University of Science and Technology,Qingdao 266500,China; School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China
• Subjects: Engineering; Machines; Manufacturing; Materials Engineering; Metallic Materials; Processes; Research & Development; eutectic structure; A; boride; high-entropy alloy; TG146.1+6; mechanical properties
• ISSN: 1672-6421; 2365-9459
• DOI: 10.1007/s41230-022-1007-4

To strengthen the face-centered-cubic (FCC) type CoCrFeNi high-entropy alloy (HEA) by in-situ reinforced phase, (CoCrFeNi) 100− x (NbB 2 ) x ( x =0, 2, 4, 6, 8, at.%) alloys were prepared. Phase constitution, microstructure, tensile mechanical properties of the alloys were studied, and the mechanisms were discussed. Results show that the microstructure of all the reinforced alloys consists of the matrix FCC phase, Laves phase, and (Cr 3 Fe)B x phase. The eutectic structure and (Cr 3 Fe)B x phases are formed in the interdendritic region, and the eutectic structure is composed of Laves and FCC phases. When x increases from 0 to 8, i.e., with increase of Nb and B elements, the volume fraction of Laves and (Cr 3 Fe)B x phases increases gradually from 0 to 5.84% and 8.3%, respectively. Tensile testing results show that the ultimate strength of the alloys increases gradually from 409 MPa to 658 MPa, while the fracture strain decreases from 75% to 1.6%. Fracture analysis shows that the crack originates from the (Cr 3 Fe)B x phase. The CoCrFeNi alloys are mainly strengthened by the second phase (Laves phase and boride phase).