Preparation of A357 Alloy Slurry by Pulsed Magnetic Field Processing

Pulsed magnetic field (PMF) processing was employed for preparing semi-solid A357 alloy slurry in this study. The effects of pouring temperature and vibration power on the microstructure of the primary phase in semi-solid A357 alloy slurry were studied, and some characteristic parameters characterized the morphology and the grain size of the primary alpha-Al particles were obtained. The results show that the primary alpha-Al particles became finer and rounder with the decrease of pouring temperature and/or the increase of vibration power. However, over a certain vibration power, coarse structures appeared again. The slurry with the primary alpha-Al particles of average diameter of approximately 92 mu m and average shape factor of 0.56 can be prepared under the action of a PMF at a vibration power of 250 W with pouring temperature of 903 K (630 A degrees C). It was feasible to use PMF processing to prepare semi-solid alloy slurry because of its strong forced convection within the whole bulk melt.