The effect of ultrasonic treatment on the microstructure of Sn-58Bi alloy

Abstract

Ultrasonic treatment of the melt metals is a hot research topic. In this paper, ultrasound was introduced from the bottom into liquid metal. By this way, the ultrasonic treatment can be acted on the liquid metal from pouring to the end of solidification. The effect of ultrasonic treatment on the microstructure of Sn-58wt.%Bi alloy are studied with the variation of different power levels. The microstructure of the treated specimen are significantly refined and only granular bismuth and tin phases is obtained, compared to the coarse dendrites microstructure without ultrasonic treatment. What's more, the refining mechanism of the microstructure is discussed. The coarse Bi phases are broken into fragments by cavitation bubbles during ultrasonic treatment and they move along with the acoustic stream and then serve as new nuclei for solidification. This process could last to the end of solidification.