Temperature effects in aluminium melts due to cavitation induced by high power ultrasound

Extensive research has been carried out previously in ultrasonic (cavitation) melt treatment. Such treatment can reduce grain size and improve material homogeneity. However, it is still not well understood which of the mechanisms is responsible for cavitation aided grain refinement. For better understanding of the processes which take place during solidification under the influence of ultrasonic vibrations, it is very important to consider the change in the cooling conditions during such treatment and thermal effects which are generated in the cavitation zone and in the bulk of liquid. The current paper presents the results of an experimental work on temperature effects in aluminium alloys and their impact on resultant microstructures. The results are discussed based on heat flow, nucleation and fragmentation during solidification.