Precipitation and Age-Hardening in Al-Si-Cu-Mg-Fe Casting Alloys

Precipitation and age-hardening in Al casting alloys containing approximately 7.0wt% Si, 3.0wt% Cu, and 0.4wt% Fe and two levels of Mg (0.08wt% and 0.4wt%) have been examined. It was found by electron microscopy that at least six different types of precipitate formed during the range of ageing treatment applied. The types of precipitate in the matrix and the relative numbers of the different types were dependent upon cooling rate after solution treatment and the magnesium content.