Effect of ultrasound on dissolution of Al in Sn

This study investigated the dissolution behavior of the aluminum substrate in molten tin at 523 K, 573 K, and 623 K with and without applied ultrasonic vibration (USV) respectively. In order to reveal the mechanism of accelerated dissolution by USV, the ultrasonic pressure distribution in the molten pool and the cavitation thermal effect were simulated by finite element analysis. Furthermore, the microstructures after the dissolution were observed. The results showed USV greatly accelerated the dissolution rate (by 21-27 times) at the interface, where an uneven ultrasonic pressure distribution in the molten pool caused inhomogeneous dissolution. The amount of Al dissolved in Sn at a particular temperature after 5 s of USV was equivalent to a holding time of 30 min without USV. The simulation results showed that the cavitation-thermal effect caused by USV increased the temperature (up to the melting point of Al) at the interfacial micro-region. It is evident that the combined effect of cavitation-thermal and ultrasonic streaming caused by USV increase the dissolution rate.