The potential for achieving superplasticity in high-entropy alloys processed by severe plastic deformation

Hamed Shahmir,Megumi Kawasaki,Terence G Langdon

doi:10.1088/1757-899x/194/1/012040

Abstract

High-entropy alloys (HEAs) are now becoming important because they offer unique combinations of solid solution strengthening and good ductility at low temperatures. Only limited information is at present available on the high temperature mechanical properties of these materials. Nevertheless, it is evident that, as in conventional metallic alloys, processing through the application of severe plastic deformation can reduce the grain size to the nanometer range and this provides a potential for achieving good superplastic elongations. The superplastic data available to date are examined in this review and a comparison is made between the behaviour of HEAs and conventional superplastic alloys.

Highlights

High-entropy alloys (HEAs) are a new class of material containing five or more principal elements with each elemental concentration between 5 at.% and 35 at.% but producing a relatively simple structure based on solid solution phases [1,2,3]
Equation (1) provides an excellent description of the superplastic flow of conventional metals with grain sizes of a few micrometers but recently it was shown by analyses that the equation applies well to bulk ultrafine-grained materials with submicrometer grain sizes produced by either equal-channel angular pressing (ECAP) or high-pressure torsion (HPT) [23,24,25]
The experimental data for HEAs are in excellent agreement with the theoretical prediction and this is consistent with conventional alloys processed by severe plastic deformation (SPD)

Summary

Introduction

High-entropy alloys (HEAs) are a new class of material containing five or more principal elements with each elemental concentration between 5 at.% and 35 at.% but producing a relatively simple structure based on solid solution phases [1,2,3]. Equation (1) provides an excellent description of the superplastic flow of conventional metals with grain sizes of a few micrometers but recently it was shown by analyses that the equation applies well to bulk ultrafine-grained materials with submicrometer grain sizes produced by either ECAP or HPT [23,24,25].

Results

Conclusion