Deformation behaviour and microstructural evolution of high-entropy CoFeMnNi alloy at hot deformation condition with low strain rate

Abstract. High-entropy alloy is a promising structural material for high-temperature service applications due to the designable superior properties. Superplasticity, normally achieved at relatively high temperature and low strain rate, enables difficult to formation materials to manufacture complex-shaped parts. This paper presents a feasibility experimental study on the deformation and microstructure of CoFeMnNi high-entropy alloy under hot deformation conditions with low strain rate. A series of hot uniaxial tests were conducted at the temperature range between 800-1000℃ with typical strain rates of 10-4 and 10-5/s to determine the stress-strain behaviours. Additionally, to understand the deformation mechanism, microstructure evolution after deformation was characterized. Finally, a mechanism based constitutive model of high-entropy alloy was developed, which facilities the process optimization by finite element simulations.