Dynamic impact behavior and deformation mechanisms of Cr26Mn20Fe20Co20Ni14 high-entropy alloy

Abstract

In this work, the dynamic impact behavior and linked deformation mechanisms of a Cr26Mn20Fe20Co20Ni14 high-entropy alloy (HEA) with face-centered cubic structure were systematically explored. The HEA displays uniform plastic deformation without any adiabatic shear bands at a strain rate range from 1000 to 3000 s−1. Moreover, the yield strength exhibits a pronounced strain rate dependence, increasing by 28% from 282 MPa at 1000 s−1 to 360 MPa at 3000 s−1. The strain hardening exponent, strain rate sensitivity and temperature rise were calculated to be 0.899–0.95, 0.076 and 64.7 K, respectively, indicative of high strain and strain-rate hardening capabilities and strong resistance to thermal softening induced adiabatic shear localization. Detailed microstructural analyses decipher a transition of deformation mechanism from dislocation slip at 1000 s−1 to stacking faults (SFs) at 2000 s−1 and further to twinning at 3000 s−1, respectively. The strengthening mechanisms are delineated as manifold interactions between glide dislocations and SFs, SFs and SFs (i.e. the Lomer-Cottrell locks), and SFs and twins. Our work provides a comprehensive understanding on the dynamic impact behavior, deformation and strengthening mechanisms of Cr26Mn20Fe20Co20Ni14 high-entropy alloy.