المستخلص: |
In this work, the effect of 0.1, 0.2, and 0.5 wt.% Mn additives on the grain size and microhardness number of Zamak 5 alloy was investigated. The Mn concentration was controlled by microalloying process. The master alloy composed of Al-10Mn wt.% was diluted to produce three microalloys. Microstructural investigation was carried out using an optical microscope and the Vickers hardness number was acquired using a microhardness tester. The grain size measurements were performed using ASTM standard test method and confirmed using the attached lens with the microhardness tester. The yield strength, strength coefficient and strain-hardening exponents were calculated from the true stress-true strain diagrams. The results showed that addition of 0.1, 0.2 and 0.5 wt.% Mn to Zamak 5 transformed the dendritic structure into more equiaxed structure with 15.5, 26.7 and 101.3 μm equivalent diameters, respectively. Furthermore, the microhardness number improved by 16.6%, 44.4% and 33.3% for the three microalloys, respectively. The calculated yield strengths and strength coefficients were consistent with the microhardness results. This improvement is an indication for property enhancing of Zamak 5 by small Mn additives. From the current study, the optimum Mn concentration that may significantly enhance the mechanical properties of Zamak 5 was 0.2 wt.%.
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