Solidification Behavior and Mechanical Property of a Highly Undercooled Al-Si Alloys

摘要

The solidification behavior of hypereutectic Al-Si alloys was investigated by electromagnetic levitation technique combining analysis of high-speed video and scanning electron microscopy. The results show that, with increasing degree of undercooling, the morphology of the primary Si transforms from dendrites to fragmented bulks and granular grains and then to equiaxed grains; the nucleation frequency increases exponentially, while the average grain size decreased exponentially. Furthermore, the effect of undercooling on microhardness was analyzed.