The Effect of Si Addition on the Microstructure and Mechanical Properties of ZA-12 Alloy

Abstract

A ZA-12 Zinc-based alloy was melted in an induction melting furnace, and cast in a graphite mold. Different amount of Si was added for examining the microstructural evolution and mechanical properties of ZA-12 alloy. All alloys were annealed at 350oC for 22 hours to investigate the effect of the heat treatment on the properties of ZA-12 alloy. The microstructure examinations revealed that while ZA-12 alloy has a dendritic microstructure with fine grains, with the Si addition the dendrite arms were broken. After annealing, it is observed that the grain size of the alloy was coarsened and Si particles were dispersed in the structure homogeneously. The Si addition was not altering the hardness of the alloys. The hardness of all alloys was decreased with the annealing. Compression tests were performed to determine the mechanical properties. These tests showed that the yield strength is decreased with Si addition, but remain constant with increasing Si content for as casted alloys. The yield elongation was decreased continuously with increasing Si content. The annealing heat treatment slightly decreased the yield strength of alloys. It was observed that all as-cast and annealed alloys were exhibiting ductile behavior.

Keywords

• Zinc-based alloys
• microstructure
• hardness
• compression strength

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