Experimental and numerical study on friction stir processing of Al0.3CoCrFeNi high entropy alloy

In this research, friction stir processing (FSP) was carried out on Al0.3CoCrFeNi high-entropy alloys (HEAs) using two different tool geometries (cylindrical and square-shaped pin) at different tool rotational speed (TRS) of 800 and 1000 rpm. Phase analysis exhibited BCC phase in both casted and friction stir processed (FSPed) HEAs. FSP of HEAs with a square-pin tool produced more refined grains in the stir zone than the cylindrical-pin tool. It was also discovered that as the TRS increased, it produced more refined grain size in the stir zone. FSP with a square-pin tool generated a processed zone having highest hardness, ultimate tensile strength, and % elongation due to the evolution of more refined microstructure. Further, a numerical study was performed using ABAQUS/Explicit finite element software to understand the complex thermo-mechanical process and to study the stress distribution, temperature distribution, and material flow behaviour during FSP. The numerical study involved the Johnson-Cook models for defining material flow behaviour during FSP. A coupled Lagrangian-Eulerian technique was used to control mesh distortion while simulating excessive deformation. The peak temperature of the FSPed zone got enhanced as the TRS increased, and the temperature enhancement was higher with a square-pin tool than a cylindrical-pin due to pulsating motion.