The Impact of Sn Additions on Microstructure, Hardness and Wear Behavior of the As-Cast AZ41 Magnesium Alloy

Abstract Magnesium alloys, especially those in the AZ series, are widely attractive for the automotive applications due to their lightweight and high specific strength. However, the wear performance of these alloys is a key factor in determining their appropriateness for ensuring durability and reliability. Therefore, the microstructure, hardness and wear resistance due to the various Sn additions on the as-cast AZ41 have been investigated. The optical microscope and an electron microscope coupled with energy dispersive spectroscopy have been used to examine the morphology of the microstructure of the investigated alloys. The hardness, wear and surface texture behavior of worn surfaces of the investigated alloys employing the Abbott-Firestone curve after wear test have also been explored. The results revealed that the as-cast AZ41 magnesium alloy containing 0.7 wt.% Sn showed significant grain refinement of the α-Mg phase from 230 to 73 µm. The hardness and the wear resistance of 0.7 wt.% Sn-containing AZ41 alloy are noticeably improved, compared to the Sn-free AZ41 alloy. Upon the addition of 0.7 wt.% Sn, the average hardness value significantly exceeds from 75 to 97 HV 3 (30% increase). On the other hand, the average wear rate of the as-cast AZ41 alloy decreased from 0.017 to 0.001067 mg/s (94% reduction) for AZ41-0.7Sn alloy. The worn surface of the AZ41 has deep scratches, plastic lines, and layers of lamination. While with 0.7 wt.% Sn, a groove on the worn surface develops discontinuous delamination layers. The findings showed that the AZ41-0.7Sn alloy has the maximum exploitation region (88%). Conversely, the AZ41 alloy displayed the lowest exploitation zone (63%). However, the highest voids region of 26% was observed for AZ41 alloy, while the lowest voids region of 0% was recorded for AZ41-0.7Sn alloy. So, the best Abbott-Firestone regions (exploitation & voids) can be achieved for AZ41-0.7Sn alloy.