DENSITY, ULTIMATE TENSILE-STRENGTH AND MICROSTRUCTURE OF A SQUEEZE CAST AL-11.8 SI-3 MG-5 GRAPHITE COMPOSITE

This paper deals with the improvements obtained in density, ultimate tensile strength and microstructure of eutectic Al-Si alloy dispersed with 5% graphite particulate, squeeze cast into square plates of 100 x 100 x 15 mm in size. The density and ultimate tensile strength of the composite increased from 2.63 to 2.67 g cm(-3) and from 75 to 145 MN m(-2), respectively, when the composite was subjected to a squeeze pressure of 50 MPa. Both primary alpha and eutectic silicon are refined owing to increased heat transfer, and pas and shrinkage porosities are minimized with pressurized solidification. The composite melt requires higher squeeze pressure than the matrix alloy. in order to obtain maximum possible properties under identical experimental conditions.