Rotary friction welding of AlCoCrFeNi2.1 eutectic high entropy alloy

AlCoCrFeNi2.1 eutectic high entropy alloy was rotary friction welded, and the evolution of microstructure and the mechanical properties of the resultant joints were investigated. Compared with the base material, the amount of eutectic cells in the heat-affected zone decreased slightly, while most grains were bended and elongated in thermal-mechanically affected zone. Grain refinement occurred in the dynamic recrystallization zone. At friction pressure of 200 MPa, the tensile strength and elongation of the joint reached 913.5 MPa and 12.1%, which are over 100% of the base metal, and fracture occurred at the base metal region far away from the weld center. While decreasing the friction pressure to 120 MPa or 80 MPa, the tensile strength of the joint degraded by 12.5% and the fracture occurred at the weld interface in the dynamic recrystallization zone. The interface appeared due to the inadequate plastic deformation under lower friction pressure and the sluggish diffusion of AlCoCrFeNi2.1 eutectic high entropy alloy.