AlxCoCrFeNi high entropy alloy with various Al contents has been successfully joined to 316L steel. The effect of mechanical properties of AlxCoCrFeNi induced by Al content on the interfacial microstructure in the 316L/ AlxCoCrFeNi has been investigated. All the 316L/AlxCoCrFeNi composite plates showed the typical interfacial microstructure of the high-velocity impact welding-periodic wavy interface. Four areas of the straight smooth area, the small wave area, the wave area, and the large wave area were along the radial direction in the interface orderly. The differences in wavelength, amplitude, ratios of the length in each area to the overall length, and the evolution of interfacial microstructure were discussed. The analysis of grain orientation, grain boundary, recrystallization, and orientation difference in the wave area showed that interfacial differences were caused by the difference in deformation mechanism of AlxCoCrFeNi matrix with different Al content. The deformation mechanism was closely related to the elongation and hardness in the macroscopic mechanical properties, which represented the ability to deformation and resist deformation, respectively. Consequently, the effect of Al content on the evolution of interface morphology was essentially the effect of hardness and elongation of AlxCoCrFeNi matrix. Additionally, all the wavy interfaces of 316L/AlxCoCrFeNi had good bonding strength in the wave area.
