Friction Stir Lap Welding Between Al and FeCoCrNiMn High Entropy Alloy

Friction stir lap welding between single-phase FeCoCrNiMn high entropy alloy (HEA) and commercial pure aluminum (1060Al) was studied. Sound joints were produced at a traverse speed of 50 mm/min and a rotation speed of 1500 RPM. The tensile shear strength reached -240 N/mm. The joint fractured at Al base material, showing a high interfacial bonding. The microstructure of joints was discussed. The interfacial structures were composed of the composite structure in the Al side, layered structure in the HEA side, and a transition layer between these two structures. In addition, significant differences in the microstructure were observed from the 1060Al side to HEA side through the interfacial microstructure. The microstructure of the HEA exhibits a complex microstructure including an equiaxed structure and an elongated structure and the average grain size was measured from nanometer to micrometer. And aluminum grains close to the weld interface were equiaxed with a complete mixture of grain orientations.