WORKHARDENING EFFECTS IN SIC PARTICLE-REINFORCED ALUMINUM-ALLOYS

Previous research by the current authors has demonstrated that thermom echanical treatments may significantly influence the monotonic propert ies, especially fracture toughness, of Al-SiCp materials through modif ication of grain size. The present paper gives a further assessment of these effects. A metal matrix composite (MMC) of aluminium alloy 2124 containing 20 wt-% of 3 mu m SiC particles was produced via a powder route at Aerospace Metal Composites and rolled to 1.8 mm sheet at DERA , Farnborough. Tensile testing showed the finest grained MMC to exhibi t the lowest workhardening rate in the naturally aged condition, which is in disagreement with conventional polycrystalline behaviour. Artif icial aging and testing in liquid nitrogen were found to increase the workhardening rate of this material. It was argued, therefore, that th e low workhardening rate was attributed to grain boundary sliding in t he highly stressed particle/matrix interface region. MST/4029.