Effects of Adiabatic Heating and Strain Rate on the Dynamic Response of a CoCrFeMnNi High-Entropy Alloy

This work presents a comprehensive analysis of the effects of strain and strain rate on the adiabatic heating and the mechanical behavior of a CoCrFeMnNi high-entropy alloy (HEA). In this investigation, compression tests were carried out at quasi-static and dynamic strain rates. The temperature of the specimens was measured using high speed infrared thermography. The high strain rate tests were conducted with a Split Hopkinson Pressure Bar, and the tests at lower strain rates were performed using a universal testing machine. The material exhibited a positive strain rate sensitivity, as true stress–strain plots were shifted upwards with the increase in strain rate. With exception of the isothermal tests, temperature rise and the Taylor–Quinney coefficient (β) were noticeably similar for the investigated strain rates. This study shows that the common assumption that β can be considered 0.9 and constant is possibly not very accurate for the CoCrFeMnNi alloy. The β is influenced by at least strain and strain rate.