ISSN: 1003-6326
CN: 43-1239/TG

Vol. 27    No. 4    April 2017

Interfacial microstructure evolution and mechanical properties of Al/Sn joints by ultrasonic-assisted soldering
Wei-bing GUO, Tian-min LUAN, Xue-song LENG, Jing-shan HE, Jiu-chun YAN
(State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China)
Abstract: Soldering aluminum alloys at low temperature have great potential to avoid softening of base metals. Pure Al was soldered with pure tin assisted by ultrasound. The influence of primary α(Al) on the microstructure of Al/Sn interface and its bonding strength was studied. It is found that the primary α(Al) in liquid tin tends to be octahedron enclosed by Al {111} facet with the lowest surface free energy and growth rate. The ultrasonic action could increase the nucleation rate and refine the particles of primary α(Al). For the longer ultrasonic and holding time, a large amount of the octahedral primary α(Al) particles crystallize at the Al/Sn interface. The bonding interface exhibits the profile of rough dentation, resulting in an increment of bonding interface area and the effect of mechanical occlusion. The bonding strength at interface could reach 63 MPa with ultrasonic time of 40 s and holding time of 10 min.
Key words: aluminum alloy; tin; ultrasonic soldering; interfacial microstructure; mechanical properties
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
Managed by Central South University (CSU)