Microstructural Characteristics of Sr And Na Modified Al-Mg-Si Alloy
B.N.Sarada1, P.L. Srinivasamurthy2, Swetha3
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The research for new materials that could be used for components with complex geometry in automotive and aircraft industries led to exploitation of Al-Si-Mg alloys. Aluminium alloys are known for easy machinability and very good casting characteristics. In this present investigation Al- 7.0Si- 0.6Mg alloy castings confirming to A357 were produced by Sand casting method and Gravity die casting method. For substantial improvement in mechanical properties Modification was carried out by adding 0.01% Sodium and 0.01% Strontium to the molten metal just before pouring into moulds. Metallographic examination was carried out to reveal the constituents and structure by means of “metallurgical Microscope”. The microstructures of as-cast alloy showed dendritic structure with large primary aluminum dendrites and the eutectic phase. Modification treatment changed Silicon morphology from needle like structure to fibrous structure, which improved mechanical properties and wear resistance of A357 alloy. The results are presented in the paper.