Effect of magnesium on mechanical properties of alumina-fiber-reinforced aluminum matrix composites formed by pressure infiltration casting

Al-Al2O3 composites containing 0.48%-6.8% Mg in the matrix alloys have been fabricated by pressure infiltration casting. Optical microscopy, scanning electron microscopy and image analysis were used to examine and to analyze the details of the microstructure and the fracture surface. Tensile tests were utilized to evaluate the mechanical properties. The addition of magnesium was found to improve the infiltration and to decrease the porosity of the composites. The tensile strength of the composites increased with increased magnesium content, while elongation remained almost constant (10%).