Influence of Tin addition on microstructure, mechanical, and tribological properties of magnesium matrix

In this study, the effect of Tin (Sn) addition on the microstructure, mechanical properties, and wear resistance of pure magnesium (Mg) was examined. Mg-Sn alloys were synthesized using stir casting technique with Sn concentrations of 2.5%, 5%, and 7.5% by weight. The specimens were prepared as per ASTM standards for their evaluation. Higher Sn concentrations result in a reduced volume fraction of the eutectic phase, while Mg2Sn precipitates are observed in alloys with 5% or more Sn. Scanning electron microscopy (SEM) analysis of the Mg-7.5wt.% Sn alloy reveals the presence of Mg(OH)2, with X-ray diffraction (XRD) confirming an oxygen content of 18% by weight. The addition of Sn minimizes casting porosity, enhancing the quality of the alloys. The findings demonstrate a positive correlation between increasing Sn content and enhanced strength and wear resistance. The Mg-7.5wt.% Sn alloy exhibits significantly enhanced tensile properties attributed to grain refinement and the formation of well-defined grain boundaries compared to alloys with lower Sn additions (2.5% and 5%), although a slight reduction in microhardness is observed. Tribological evaluation indicates reduced wear and friction, suggesting better surface performance. This research underscores the complex interplay between Sn content, microstructural evolution, and the resulting mechanical and tribological performance of Mg-Sn alloys.