Refinement of eutectic grains by combined addition of strontium and boron in near-eutectic Al–Si alloys

Combined addition of strontium and boron led to a much greater decrease in the eutectic grain sizes in near-eutectic Al–Si alloys than that caused by addition of strontium alone. As expected, an increased cooling rate during solidification refines the eutectic grains. The mechanism of this refinement in the presence of strontium and boron is related to the combined effect of increased undercooling of the eutectic reaction and the effective number density of eutectic nuclei.