EFFECT OF MAGNESIUM ON MECHANICAL-PROPERTIES OF AL2O3 AL-ZN-MG-CU METAL-MATRIX COMPOSITES FORMED BY SQUEEZE CASTING/

Al2O3/Al-Zn-Mg-Cu composites containing 2.0 similar to 3.0 wt.% Mg in the matrix alloy have been fabricated by squeeze casting. Light micros copy, scanning electron microscopy and image analysis were used to exa mine and analyze the details of microstructure and the fracture surfac e. Tensile tests were utilized to evaluate the mechanical properties. The aging behavior of the composites was studied by using differential scanning calorimetry technique and microhardness tests. The microhard ness and ultimate tensile strength (UTS) of the composites increase wi th increasing Mg content. The maximum microhardness and UTS of the com posites occur at 120 degrees C aging for 24 h.