In-situ Si particle-reinforced joints of hypereutectic Al-60Si alloys by ultrasonic-assisted soldering
(Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China)
Abstract: To improve the wettability of hypereutectic Al-60Si alloy and enhance the mechanical properties of the joints, Al-60Si alloy was joined by ultrasonic soldering with Sn–9Zn solder, and a sound joint with in-situ Si particle reinforcement was obtained. The oxide film of Al-60Si alloy at the interface was identified by transmission electron microscopy (TEM) analysis as amorphous Al2O3. The oxide of Si particles in the base metal was also alumina. The oxide film of Al-60Si alloy was observed to be removed by ultrasonic vibration instead of holding treatment. Si particle-reinforced joints (35.7 vol.%) were obtained by increasing the ultrasonication time. The maximum shear strength peaked at 99.5 MPa for soldering at 330 °C with an ultrasonic vibration time of 50 s. A model of forming of Si particles reinforced joint under the ultrasound was proposed, and ultrasonic vibration was considered to promote the dissolution of Al and migration of Si particles.
Key words: hypereutectic Al-60Si alloy; ultrasonic-assisted soldering; Si particle reinforcement; Sn-9Zn solder