Hypereutectic Aluminium-Silicon Casting Alloys—A Review

The structure, properties and uses of hypereutectic aluminium-silicon foundry alloys are reviewed. Emphasis is placed on the control of primary silicon morphology through phosphorus treatment. The effects of various process variables on the silicon structure are discussed. Experimental work related to the simultaneous refinement of primary silicon and modification of the eutectic is reviewed. It is concluded that beneficial effects can be obtained by simultaneous refinement and modification, although the primary silicon is never as finely distributed as when only phosphorus refined.