Superior bonding of Al/Mg interface by introducing nanocrystals via high-entropy alloy coating and ultrasonic vibration

A novel FeCoNiCrCu high-entropy alloy (HEA) coating and ultrasonic vibration composite treatment method were developed to prepare the Al/Mg bimetal to enhance the Al/Mg interface. Elemental interdiffusion at the Al/HEA interface led to the formation of AlxFeCoNiCrCu. The HEA/Mg interface melted due to friction heat and cavitation effect by ultrasonic vibration and then cooled at an extremely high cooling rate to form nanocrystals. The presence of the nanocrystals hindered dislocation movement, resulting in difficulty in crack propagation, significantly improving the shear strength of the Al/Mg bimetal, which increased from 34.52 MPa without treatment to 77.86 MPa, increasing by 125.55%.