An aluminium composite has been processed by squeeze casting and hot extrusion and the tensile properties at room temperature have been determined. The strength contributions of oxide particles and subgrains in the extruded state have been calculated. The effect of heat treatment (T4) is discussed and it is suggested that precipitation hardening occurs during cooling both after casting and after hot extrusion and therefore contributing significantly to the flow stress also of the nonheat treated composites. The maximum yield strength (0·2% offset) is 550 MPa, obtained in a composite containing 50 vol.-%Al2O3 after heat treatment for 1 h at 490°C (T4).
