Abstract
A combined casting-forging approach was employed to develop hybrid metal matrix composites using Mg-enriched 2218 as matrix and multiple reinforcements of Al2O3 and TiO2 particles. The forging pressure was varied from 0 to 200 MPa. The composites were given T6 thermal treatment. The composites were tested for tensile properties at elevated temperatures up to 400 degrees C and fracture behavior was characterized based on forging pressure, reinforced particles, dimple size and their number in coherence with the microstructures. The pressure applied during forging had a positive effect on the porosity, alloy-particle bonding, interfacial strength and segregation of the solutes, resisting the interdendritic cracking. The reinforcement restricted void growth. The transition of fracture mode from semi-ductile to ductile was observed as the test temperature was increased and from ductile to brittle when the forging pressure was increased.