Development of Mg-Sb-Sn and Mg-Sb-Ca Magnesium Alloys for Automotive Applications: Microstructure, Mechanical Properties, and Corrosion Behavior Analysis

In the present study, two Mg-Sb-Sn and Mg-Sb-Ca alloys were prepared, and their microstructure, mechanical and corrosion properties were studied systematically. The microstructure of the Mg-4 wt.% Sb-(2,4 wt.%) Sn alloys showed primary α-Mg as white region and eutectic α-Mg as dark region. As Sn content increased from 2 to 4 wt.%, the Mg₃Sb₂ and Mg₂Sn phases were seemed to be finer and the number of Mg₂Sn phases were increased. The Mg-4 wt.% Sb-(2,4 wt.%) Ca alloys composed of α-Mg and MgSbCa phases. As Ca content increased from 2 to 4 wt.%, volume fraction of MgSbCa phase increased and its morphology was changed from shorter network to lengthy skeleton-like structure. The increased amount of finer Mg₂Sn and Sb-Sn-rich phases and the α-Mg refinement increased strength of Mg-4 wt.% Sb-4 wt.% Sn alloy compared to Mg-4 wt.% Sb-2 wt.% Sn alloy. The refinement of α-Mg dendrites and a higher fraction of MgSbCa phases increased strength of Mg-4 wt.% Sb-4 wt.% Ca alloy compared to Mg-4 wt.% Sb-2 wt.% Ca alloy. Increased addition of Sn from 2 to 4 wt.% suppressed Mg₃Sb₂ phases in Mg-4 wt.% Sb-4 wt.% Sn alloy, that deteriorate creep resistance of this alloy related to Mg-4 wt.% Sb-2 wt.% Sn alloy. The presence of lengthy skeleton-type MgSbCa phases reduced creep resistance of Mg-4 wt.% Sb-4 wt.% Ca alloy compared to Mg-4 wt.% Sb-2 wt.% Ca alloy. The long-term immersion test results demonstrated that the corrosion resistance of the Mg-4 wt.% Sb-4 wt.% Sn alloy was higher compared to the Mg-4 wt.% Sb-2 wt.% Sn alloy. Additionally, due to the lower cathode/anode surface area in the Mg-4 wt.% Sb-2 wt.% Ca alloy, it exhibited higher corrosion resistance than the Mg-4 wt.% Sb-4 wt.% Ca alloy.