High strain rate compression behaviour of single phase CoCuFeMnNi high entropy alloy

Abstract

Deformation behaviour of FCC CoCuFeMnNi single phase high entropy alloy (HEA) was studied under quasistatic and dynamic loading conditions in compression at strain rate of 0.001 s−1 and 3000 s−1 using screw driven universal testing machine and split Hopkinson pressure bar respectively. A detailed microstructural characterization was carried out using electron back scatter diffraction (EBSD) while bulk texture measurement was carried out using X-ray diffraction. The high strain rate deformed sample shows high strain rate hardening as well as higher strain hardening that is attributed to operation of deformation twinning as observed from EBSD. The operation of deformation twinning and multiple slip systems leads to grain fragmentation and weakening of characteristic <101> compression texture in sample subjected to high strain rate. Constitutive behaviour of the CoCuFeMnNi HEA explained using the Johnson-Cook model further justifies better strain rate and strain hardening response of the alloy compared to individual elements.