Rapid and reliable metallurgical cladding of Sn-0.7Cu solder onto ADC12 Al alloy driven by ultrasonic-electric coupled field

In this study, an ultrasonic-electric coupled cladding method was developed to achieve rapid and reliable metallurgical cladding of Sn-0.7Cu solder onto ADC12 Al alloy. Using a coupled field could combine the advantages of both ultrasonic and electric fields. The differences in microstructure, cladding ratios, and mechanical properties of samples between ultrasonic cladding and ultrasonic-electric coupled cladding were compared. Results showed that a diffusion layer composed of α-Al, eutectic Si, and Al₂Cu phases was formed at the cladding interfaces of both cladding methods. Adding an ultrasonic-electric coupled field could improve cladding efficiency and enhance interfacial reactions. When the substrate was connected to the cathode, the substrate erosion was intensified. The cladding samples prepared using ultrasonic-electric coupled cladding for 1s exhibited the cladding ratio and shear strength of 98.72 % and 16.57 MPa, representing improvements of 43.11 % and 279.17 % compared to those of ultrasonic cladding. The initial oxide film at the cladding interface was rapidly removed under the coupled field, and an amorphous Al₂O₃ layer was in-situ formed. The enhanced cladding behavior was primarily attributed to the synergistic effects of electrocaloric, cavitation, current accumulation, and Marangoni effects. This study may offer a promising cladding strategy for improving the solderability of Al alloys.