J. Mater. Sci. Technol. ›› 2021, Vol. 60: 35-43.DOI: 10.1016/j.jmst.2020.03.078

• Research Article • Previous Articles     Next Articles

Microstructural and mechanical behavior of a CoCrFeNiCu4 non-equiatomic high entropy alloy

Zijuan Xua, Zhongtao Lia, Yang Tongc, Weidong Zhanga,*(), Zhenggang Wua,b,*()   

  1. a College of Materials Science and Engineering, Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082, China
    b State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China
    c Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
  • Received:2020-02-08 Revised:2020-03-07 Accepted:2020-03-26 Published:2021-01-10 Online:2021-01-22
  • Contact: Weidong Zhang,Zhenggang Wu


High entropy alloy (HEA)-based alloy design is experiencing a conceptual broadening from equiatomic alloys to non-equiatomic alloys. To provide experimental basis for designing Cu-rich non-equiatomic HEAs, in the current study, a dual phase (Cu-rich and CoCrFeNi-rich phases) face-centered cubic CoCrFeNiCu4 alloy was systematically investigated. We provided initial and experiment-based understanding of the behavioral change of the alloy during a variety of thermal cycles and thermomechanical processing. The current results indicate that, during heating, preferred precipitation of Cu-rich particles occurs, leading to more pronounced compositional differences between the two constituent FCC phases and increased relative volume fraction of the Cu-rich phase. The Alloy exhibits a continuous melting and discontinuous solidification of the Cu-rich and CoCrFeNi-rich phases. After being cold-rolled to ~ 90 % thickness reduction, the alloy exhibits a recrystallization temperature higher than 800 °C. Annealing at 300 and 500 °C led to strength reduction and/or ductility decrease; further increasing annealing temperature monotonically caused softening and ductilization due to decreased density of pre-existing dislocations. The yield-drop phenomena observed for the 900 °C- and 1000 °C-annealed specimens are associated with the locking of pre-existing dislocations by some “atmosphere”, the nature of which warrants further elucidation.

Key words: High entropy alloy, Non-equiatomic alloy, Microstructure, Melting and solidification, Mechanical behavior