Microstructure evolution and mechanical properties of 5083 aluminum alloy joints by ultrasonic soldering

Abstract

Aluminum alloy 5083 was joined with Sn–[Formula: see text]Zn ([Formula: see text], 5, 9, 30 and 60 wt.%) filler metal by ultrasonic soldering at 400[Formula: see text]C. The joint microstructure consisted of [Formula: see text]-Sn and [Formula: see text]-Al solid–solution phases when using pure Sn solder. Zn-rich phases were observed in the joints with Sn–Zn filler metal. The Zn-rich phases grew thicker and larger with the increase in Zn content in the filler metal. The joints soldered with Sn–30Zn filler metal reached a maximum shear strength of 70 MPa. Joint cracking occurred at the interface of pure Sn and Sn–9Zn solders as indicated by SEM observation of the fracture surfaces. The locations of the fracture surface moved from the interface to the seam when using the Sn–30Zn or Sn–60Zn filler metal. The coarse Zn-rich phases were also observed on the fracture surface using Sn–60Sn solder, which results in a shear strength reduction of the joints.