Effect of magnesium on strength and microstructure of Aluminium Copper Magnesium Alloy

Cast Al - Cu- Mg alloys have w idely used in aircraft, aerospace, ships and boat making, industrial and architectural applications for their good mechanical properties, high strength-to-weight ratio. An intensive study of these cast aluminium family has been found in the literature in terms of enhancing the mechanical properties. The objective of this paper was to investigate the influence of magnesium on microstrructural changes and mechanical properties such as tensile strength and hardness of the Al4Cu alloys. The modifications of Al4Cu by adding Mg of 0.5 to 2 % in the interval of 0.5% mixing w ith stirrer and casted by gravity die casting, subsequently the specimens w ere subjected T6 type heat treatment for 5 hr at 175C. The effect of Mg and ageing on microstructure was studied by using optical microscope w ith image analysis software for measuring grain size and dendrite arm spacing. The mechanical properties such as tensile strength and hardness were studied using universal testing machine and Brinell hardness tester respectively. The micro-structural analysis result shows the 2 % addition of Mg reduces the 20% grain size and 21.52% dendrite structure. The tensile strength and hardness increasing with % of Mg. The addition of 2% Mg increases tensile strength 57.9% and hardness of 25%. Aging specimens showed that 1% of Mg influence more on grain refinement and mechanical properties due to smaller the grain size.