Microstructure evolution and mechanical properties of the Sip/Zn-Al composite joints by ultrasonic-assisted soldering in air

Hypereutectic Al-27Si alloys were joined without flux by ultrasonic-assisted soldering at 420 ℃ in air using Zn-5Al the filler alloys, and Si particulate-reinforced Zn-Al based composites filler joints were obtained. The ultrasonic vibration introduced into soldering could influence the migration of Si particles and the microstructure of solidified Zn-Al based alloys. Both the distribution of Si particles and microstructure of the solidified Zn-Al based alloys affected the shear strength of joints. The shear strength increased with the ultrasonic vibration time. The highest average shear strength of joints reached to ～68.5 MPa. Transcrystalline rupture mode was observed on the fracture surface.