The Observation of a Cellular Reaction in a Ni ₃₆Co ₁₈Cr ₂₀Fe ₁₉Al ₇ High-Entropy Alloy after Quenching and Annealing

Abstract

High-entropy alloys (HEAs) are composed of three or more elements. The development of HEAs requires knowledge of phase transformations influencing the synthesis techniques. In this paper, phase transformations of a Ni₃₆Co₁₈Cr₂₀Fe₁₉Al₇ HEA have been studied. The methodology includes heating to and quenching from 1323 K, followed by isothermal holding at 873 K. Not only coherent fine L1₂ particles precipitate homogeneously in austenite, but also lamellae of austenite and L1₂ phase nucleate and grow from the grain boundaries. Subsequently, a cellular reaction occurs and high-temperature austenite transforms into low temperature lamellar austenite and L1₂ phase, i.e., austenite -> austenite + L1₂.

Keywords: high-entropy alloy, cellular reaction, L12 phase