Microstructure and mechanical properties of a high volume fraction SiC particle reinforced AlCu4MgAg squeeze casting

The microstructure and mechanical properties of a high volume fraction SiC particle reinforced AlCu4MgAg alloy produced by squeeze pressurised infiltration of dense packed particle preforms were characterised. It was found that the addition of 60 vol.% 12 μm SiC particles eliminates the processing related intrinsic macrosegregation of the matrix alloy, induces coarse precipitates in as-cast matrix, but does not impede matrix grain growth. The SiC–Al interfacial chemical reaction is suppressed to a limited extent. In T6 condition, the interfacial intermetallics are largely dissolved and the matrix is decorated with fine and dense precipitates of θ′ and Q phases. The addition of SiC particles accelerates the age-hardening response of the matrix alloy. Mechanically, the stiffness, hardness, flexural strength, fatigue strength and abrasive wear resistance are substantially improved, together with significantly reduced fracture toughness and ductility in comparison with the matrix alloy.