Dynamic softening kinetics of Al0.3CoCrFeNi high-entropy alloy during high temperature compression and its correlation with the evolving microstructure and micro-texture

Abstract

To establish the characteristics and kinetics of dynamic softening in a Al0.3CoCrFeNi high–entropy alloy (HEA), isothermal compression tests were carried out in a suitable temperature range of 1273–1423 K at 10−2 and 10−1 s−1 in accord with our previous study. It was found that the discontinuous dynamic recrystallization (DRX) was the dominant microstructural reconstitution mechanism. The conditions of critical stress/strain for the onset of dynamic recrystallization were determined using the Poliak–Jonas analytical criterion. Further, a kinetic model was established based on the Avrami-type function in order to be able to predict the volume fraction of DRX. The DRX volume fraction expectedly increased with strain. The microstructural investigation of the isothermally compressed specimens revealed a good agreement with the proposed DRX kinetics model and validated its accuracy. Additionally, the evolution of DRX with strain was characterized by interrupting the test carried out at 1323 K/10−1 s−1 at different strains. The progress of DRX evolving as increased formation of new recrystallized grains further corroborated the predictions of the kinetic model. The micro-texture analysis revealed random texture in the recrystallized grains, whereas the unrecrystallized grains had shown their preferred orientation towards the fiber texture.