RHEOCASTING OF A356 ALLOY BY LOW SUPERHEAT POURING WITH A SHEARING FIELD

A novel semi-solid slurry-making process was developed, which was a controlled nucleation and growth technique using a specially designed rotational barrel. Experimental study was undertaken to investigate the effects of pouring temperature and rotation speed of barrel on the microstructure of A356 alloy. Localized rapid cooling, combined with vigorous mixing during the initial stage of solidification enhanced wall nucleation and nuclei survival. High nuclei density combined with a much gradual cooling afterwards led to the formation of the near-ideal semi-solid shiny under a large processing window for the pouring temperature. Primary phase presented in mean equivalent diameter of 50-70 μm and shape factor of 0.812-0.847, and featured zero-entrapped eutectic.