Role of calcium in aluminium based alloys and composites

The role of calcium in aluminium alloy systems is reviewed, commencing with a survey of binary and ternary Al–Ca(–X) alloy systems. The influences – both beneficial and deleterious – of calcium on the physical, electrical and mechanical properties of aluminium alloys are considered. Beneficial applications of Ca include modifier in Al–Si alloys, iron neutraliser in recycled aluminium alloys with high iron content, scavenger of Sb, P and Bi from secondary alloys, thickening agent in the production of aluminium foams and wetting promoter in the synthesis of aluminium metal matrix composites; as an alloying element, Ca can also impart superplasticity. The interaction of Ca with other elements, high temperature oxidation, and applications of Al–Ca alloys are discussed and avenues for further work recommended.