High-pressure torsion of face-centered cubic multi-principal element alloys: Nanostructuring and its influence on properties
Avanish Kumar Chandan, Kaushal Kishore, Megumi Kawasaki, Terence G. Langdon, Jenő Gubicza
Abstract
A decade of research combining multi-principal element alloys (MPEAs) processed by high-pressure torsion (HPT) and possessing unique effects has generated considerable anticipated and unexpected insights related to the deformation behavior and properties of these alloys. Processing by HPT offers a simple route for obtaining nanostructured grains, thereby overcoming the long-standing issue of the low yield strength in face-centered cubic (FCC) MPEAs. This review provides the first comprehensive report on the processing‒structure‒property relationship in the realm of FCC MPEAs. It casts light on the breakdown of the conventional stacking fault energy‒deformation mechanism correlation for HPT-processed FCC MPEAs, the unexpected occurrence of deformation-induced phase transformations and it clarifies the role of different material-specific as well as processing-dependent factors dictating the grain refinement down to the nanoscale regime. Additionally, a detailed discussion is presented on the potential of HPT processing to achieve outstanding mechanical properties for FCC MPEAs. The multifunctional aspects of the nanostructured FCC MPEAs are critically examined from the viewpoint of their high temperature stability, corrosion resistance and susceptibility to hydrogen embrittlement. Accordingly, this review provides a pathway for future research by highlighting the key research gaps and the opportunities for niche industrial applications of FCC MPEAs processed using HPT.