Investigation of the strain rate sensitivity of CoCrFeMnNiTix (x = 0, 0.3) high-entropy alloys using the shear punch test

Abstract

High entropy alloys (HEAs) are a novel class of metallic materials that exhibit a unique blend of properties due to their chemical composition and atomic arrangement. This research aims to investigate the strain rate sensitivity (SRS) of two HEA CoCrFeMnNiTix (x = 0, 0.3) alloy compositions through the use of shear punch testing. This method has been proven to provide reliable results for both HEA materials, including the CoCrFeMnNiTi0.3 HEA composition which was found to be inherently brittle and contained both σ-phase and Laves phase compounds with a hardness close to 14 GPa and a soft FCC phase. Among all the testing temperatures (room temperature to 400 °C) and deflection rates (0.2, 2 and 10 mm.min−1) used, only the CoCrFeMnNi HEA alloy was found to exhibit SRS at room temperature (m = 0.0333), while for the other HEA alloy variant and testing conditions, the SRS was found to be zero. From empirical correlations and finite element analysis (FEA), the calculated value for m ranged from 0.0333 to 0.0359, thus evidencing that the FEA simulations provide an accurate and suitable means of capturing the deformation behaviour of such alloys when subjected to shearing.