For Al-11.6%Si alloy,the influence of the addition of Sr on the morphology of the
dendrite α phase was investigated,and the characteristic parameters of the dendrite α phase,the
primary dendrite spacing and the secondary dendr ite arm spacing,were also measured. The addition of
strontium promotes the colu mnar dendrite growth and leads to a decrease of both the primary dendrite spacin g and
secondary dendrite arm spacing with the increase of the content of stronti um in the modified near-eutectic Al-Si alloys. It is thought that the addition of Sr leads to a reduction of the solid-liquid interfacial energy of the dendr ite α phase,consequently resulting in a decrease of the growth undercoolin g of dendrite tips. And hence,the nucleation of the equiaxed grains in the liqu id in front of the columnar dendrite tips is restrained,thus the addition of st rontium in Al-Si
alloys promotes the growth of the columnar dendrites. The redu ction of the solid-liquid interfacial energy also leads to the decreases in the primary dendrite
Spacing and the secondary dendrite arm spacing.
More summaries about the Effect of strontium on columnar growth of dendritic α phase in near-eute ctic Al-11.6%Si alloys