Modification effect of Sr on the microstructures and mechanical properties of Al–10.5Si–2.0Cu recycled alloy for die casting

The effect of Sr addition on the microstructure and mechanical properties of Al–10.5Si–2.0Cu (in wt%) recycled die-casting alloy was studied. With increasing Sr content, the morphology of the eutectic Si evolved from coarse acicular → lamellar → fine fibrous shapes. Sr addition significantly improved the mechanical properties, with the tensile strength being increased from 209 to 237 MPa and the elongation from 2.0 to 4.1%. This improvement was associated with the morphological evolution of the eutectic Si and was qualitatively evaluated by using a quality index.