The Role of Substructural Features on the Deformation and Fracture Behavior of BCC and FCC High Entropy Alloys

Abstract

The applicability of high entropy alloys (HEAs) as useful structural components is limited due to our lack of systematic understanding of the role of micro- and sub-structural features on their deformation and fracture behaviour. Synergistic assessment of fracture toughness (FT) and activation volume (V) for plastic deformation of typical BCC and FCC HEAs containing Al-Cr-Co-Cu-Fe-Ni by standard practices have been made to throw some light in this direction; these assessments are supplemented by micro- and sub-structural examinations using electron microscopy together with measurements of conventional mechanical properties. The major results indicate that the BCC alloy exhibits higher hardness and strength with inferior FT compared to the FCC alloy. This observation has been explained using the estimated magnitudes of V which is governed by the operative deformation mechanisms controlled by the nature of dislocations in the concerned microstructural constituents.