Cast and investigate the characteristics of a high strength aluminium, copper and silver alloy

Jonathan Couch


This is an investigation into the effect of adding pure silver to a ‘duralumin’ type alloy and its impact on hardness and strength. The alloys were produced as small cuboid ingots by gravity casting into graphite molds and cooling in air. The silver content added ranged from zero to 10 per cent by weight. The following consecutive stages were used; casting; homogenisation, solution treatment, ageing for 2 hours and ageing for 4 hours. Post-casting the alloy ingots were heat treated simultaneously to ensure all samples had been subjected to the same conditions. After each stage of the investigation a slice was taken from each sample and mounted in Bakelite. The mechanical property of hardness was investigated by means of a Vickers hardness tester. The materials’ microstructure was examined under both an optical microscope and a scanning electron microscope in order to further understand the mechanisms that had contributed to the increase in the material’s strength. It was found that strength and hardness increased with silver content up to 10%. And a principle mechanism that caused this was the formation of precipitates in the materials’ microstructure. 

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