Abstract
Previous research by the current authors has demonstrated that thermomechanical treatments may significantly influence the monotonic properties, especially fracture toughness, of Al-SiCp materials through modification of grain size. The present paper gives afurther assessment of these effects. A metal matrix composite (MMC) of aluminium alloy 2124 containing 20 wt-% of 3 μm 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 exhibit the lowest workhardening rate in the naturally aged condition, which is in disagreement with conventional polycrystalline behaviour. Artificial aging and testing in liquid nitrogen were found to increase the workhardening rate of this material. It was argued, therefore, that the low workhardening rate was attributed to grain boundary sliding in the highly stressed particle/matrix interface region.
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