Solidification Behavior of Spray Atomized Silicon Droplets

摘要

Twin lamellae structures with (110) and (211) directions are observed in atomizedsilicon powders. The thickness of the twin lamellae increases with increasing droplet size. The growth mechanism and resulting microstructure are undercooling dependent. The lamellae structure may stem from the low undercoolings that are present during the solidification of the atomized silicon droplets. The transition from the edgewise growth mechanism to the continuous growth mechanism occurs from low undercooling to high undercooling. The (110) to (211) dendritic transition is attributed to a break-up of the coherent growth of two (211) dendritic growths. The cooling rate that is experienced by atomized silicon droplets is calculated to be 10(exp 3)-10(exp 5) K/s. The homogeneous