Influence of Strontium Addition on Microstructure and Mechanical Properties of an Al–10Si–5Cu Alloy

The microstructure and mechanical properties of Al–10Si–5Cu cast alloys with micro-addition of alloying elements (V, Cr and Ni) were studied before and after strontium addition. Samples were examined using the X-Ray diffraction, the optical microscope, the scanning electron microscope and the energy dispersive spectrometer. The results indicated that the α-Al matrix, eutectic Si phase and Al2Cu phase were the main constituent phases of Al–10Si–5Cu alloys before or after strontium addition. Strontium addition affected the refining of the α-Al grains and transforming the configuration of interdendritic phases. The un-modified alloy showed a brittle nature because of existing brittle and aggregated AlSiMnFe phases. Contributing to the alteration of microstructure in strontium modified alloy, the strength and elongation of the alloy were improved. In addition, the fracture mechanism and crack propagation process were investigated in both the alloys.