Solidification of Pb-Sn alloys under ultrasonic field

Grain size reduction and improved material homogeneity through ultrasonic treatment of a melt are well-established facts; however, the mechanisms responsible for cavitation aided grain refinement are still not well understood. For an in depth analysis of processes taking place during solidification, it is very important to consider the changes in the cooling conditions during the ultrasonic treatment. In addition, the thermal effects generated in the cavitation zone and in the bulk of liquid melt also need to be investigated. In this present work, experiments were performed to investigate any temperature effects in Pb-Sn alloys and study their impacts on the resulting microstructures. The results are discussed in relation to heat flow, nucleation and fragmentation during solidification.