Characterization of hot deformation behavior of Al0.3CoCrFeNi high entropy alloy and development of processing map

Abstract

This study presents the characteristics of hot deformation behavior of a Al0.3CoCrFeNi high entropy alloy in the temperature and strain rate ranges of 1023–1423 K and 10–3–10 s–1, respectively. The constitutive flow behavior was modeled based on the hyperbolic–sinusoidal Arrhenius–type equations and a mathematical relation was used to observe the influence of true – strain on material constants. To define hot workability of the alloy, a processing map was developed based on the principles of dynamic materials model. Accordingly, a dynamic recrystallization (DRX) domain in the temperaure and strain rate ranges of 1273–1423 K and 10–2–2 x 10–1 s–respectively, with a peak efficiency of ~45 % at 1423 K/6 x 10–2 s–1, was identified as prudent for processing. At lower temperatures (1048–1148 K) and strain rates (10–3–3x10–3 s–1), a dynamic recovery (DRV) domain was identified with a peak efficiency of 38% at 1123 K/10–3 s–1. A large instability regime occurred above 3x10–1 s–1 with an increased tendency of adiabatic shear bands. It extended to lower strain rates 10–2–10−1 s−1 at temperatures <1123 K, manifested by localized shear bands and grain boundary cracking . At low strain rates (5x10–3–10–3 s–1) and temperatures (1148 – 1298 K), particle stimulated nucleation of new DRX grains occurred at B2 precipitates, though the efficiency of power dissipation dropped sharply to 9%.