Morphological evolution of semi-solid Mg2Si/AM60 magnesium matrix composite produced by ultrasonic vibration process

The application of ultrasonic vibration treatment (UVT) produced a nearly non-dendritic and refined semi-solid microstructure of Mg2Si/AM60 composite. The effects of UVT temperature and time on microstructure of the semi-solid slurry were studied. A good semi-solid slurry with average grain size of 75 μm and shape coefficient of 0.53 could be obtained by applying UVT at 620 °C for 60 s, which were decreased by a factor of 17/20 and increased by a factor of 3 respectively as compared to the sample without treatment. The Mg2Si and Mg17Al12 intermetallics are mainly located along the grain boundaries or dispersed uniformly in the metallic liquid matrix with network morphology. Mechanisms involved in the development of microstructure are discussed.