Superplasticity in Severely Deformed High-Entropy Alloys

Abstract

High-entropy alloys (HEAs) are a new class of material producing superior properties that have a potential for replacing many structural materials in industry. Single-phase solid solution HEAs with face-centered cubic crystal structure show significant ductility and toughness over a wide temperature range including at cryogenic temperatures. Nevertheless, the occurrence of decomposition at elevated temperatures is challenging for many applications. These materials reveal sluggish diffusion and therefore high thermal stability so that processing by severe plastic deformation gives increased kinetics of decomposition and leads to fine-multiphase microstructures which provide a potential for achieving superior superplastic elongations. The present review is designed to examine the available superplastic data for HEAs and thereby to compare the behavior of HEAs with conventional superplastic alloys.

Fig. 12 Temperature and grain size compensated strain rate versus normalized stress showing excellent agreement with the theoretical prediction for conventional superplasticity.⁶⁴⁾