Phase Transformation Kinetics of a FCC Al0.25CoCrFeNi High-Entropy Alloy during Isochronal Heating

Jun Wang,Haoxue Yang,Tong Guo,Chen Wei,Tingting Xu,Jinshan Li

doi:10.3390/met8121015

Abstract

The phase transformation kinetics of a face-centered-cubic (FCC) Al0.25CoCrFeNi high-entropy alloy during isochronal heating is investigated by thermal dilation experiment. The phase transformed volume fraction is determined from the thermal expansion curve, and results show that the phase transition is controlled by diffusion controlled nucleation-growth mechanism. The kinetic parameters, activation energy and kinetic exponent are determined based on Kissinger–Akahira–Sunose (KAS) and Johnson–Mehl–Avrami (JMA) method, respectively. The activation energy and kinetic exponent determined are almost constant, indicating a stable and slow speed of phase transition in the FCC Al0.25CoCrFeNi high-entropy alloy. During the main transformation process, the kinetic exponent shows that the phase transition is diffusion controlled process without nucleation during the transformation.

Highlights

High-entropy alloys (HEAs) have attracted extensive attention as its unique designing philosophy and excellent comprehensive properties such as high strength, high toughness and good corrosion resistance [1,2,3,4,5]
Niu et al [12] studied the tensile properties of Al0.5 CoCrFeNi HEAs annealed at 650 ◦ C and found the alloy is highly strengthened by nanoprecipitations
0.25CoCrFeNi HEA measured at heating rate of rate of Figure

Summary

Introduction

High-entropy alloys (HEAs) have attracted extensive attention as its unique designing philosophy and excellent comprehensive properties such as high strength, high toughness and good corrosion resistance [1,2,3,4,5]. Heat treatment is widely used for many kinds of materials in order to obtain ideal integrated properties effectively without macro appearance destruction. Implementation of heat treatment to high-entropy alloys achieved many successful cases [6,7,8,9,10,11]. Niu et al [12] studied the tensile properties of Al0.5 CoCrFeNi HEAs annealed at 650 ◦ C and found the alloy is highly strengthened by nanoprecipitations. Munitz et al [8]

Results

Discussion

Conclusion