Constitutive Behavior With Microstructure and Texture Evolution During the High-Temperature Deformation of Fe11.5Co20.6Ni40.7Cr12.2Al7.8Ti7.2 High-Entropy Alloy

Abstract

Microstructure and texture evolution of the Fe11.5Co20.6Ni40.7Cr12.2Al7.8Ti7.2 (at. pct) high-entropy alloy during the high-temperature deformation has been investigated in the temperature range of 1173 K to 1373 K and strain rate of 0.1 to 0.001 s−1. The stress–strain curve obtained from the deformation indicates significant flow softening at low temperatures. The softening at 1173 K is due to cracking, whereas high-temperature softening is attributed to dynamic recrystallization (DRX). Arrhenius-type sine hyperbolic relationship is used to carry out the flow stress analysis, and the predicted flow stress shows good agreement with the experimental results with an accuracy of (R 2 = 0.955), especially when the deformation takes place at a low strain rate. The estimated strain hardening exponent, n (&gt

3), and activation energy, Q (&gt

400 kJ/mol), indicated that the deformation mechanism is dislocation controlled. Detailed microstructural and textural characterization of the hot deformed sample has been carried out using EBSD analysis. Microstructural investigation confirms that dynamic recrystallization is the primary reason behind the flow softening for the samples deformed at 1273 K and above. Strain-free recrystallized grains are found to nucleate near the grain boundary region. Furthermore, the size of the recrystallized grains increases with an increase in temperature and a decrease in strain rate. The volume fraction of the recrystallized grains is found to decrease with an increase in the Zener Holloman parameter. DRX grain was found to possess a weak texture with a low texture index. © 2023, The Minerals, Metals & Materials Society and ASM International.