Study of Some Physical Properties of Cast Mg Alloys

Abstract

Magnesium and its alloys are promising candidates in transportation industry. Magnesium alloys possess some excellent advantages of high specific strength, low density, good damping behaviour, high toughness, good electrical and thermal conductivites, low machining cost, good castability, strong electromagnetic shielding, and good heat dissipation. The Mg-Sn alloy system is a good contender for being both thermally stable and RE-free. However, it has significant drawbacks that limit its industrial use, such as a coarse microstructure that results in poor mechanical properties. As a result, the goal of this research is to solve the Mg-Sn system's shortcomings by adding various alloying elements and studying their effects on microstructure, mechanical, and corrosion properties. The effect of 0.5 wt. % percent Sb and Bi added to Mg-4Sn based alloys on microstructure, mechanical characteristics, and corrosion behaviour was investigated in this work. Optical microscope, scanning electron microscope, and X-ray diffraction technique were used to investigate the effect on microstructure. The effect on mechanical properties was studied using tensile testing, Vickers hardness testing and indentation creep testing, whilst corrosion behaviour was studied through different techniques; immersion testing, potentiodynamic polarization testing, as well as electrochemical impedance spectroscopy. According to the results, the base alloy's grain size is greatly refined following Bi addition. Bi addition also improves mechanical characteristics as well as

corrosion resistance. This caused as a result of the development of the Mg3Bi2 secondary phase. The base alloy has a coarse microstructure and poor mechanical and corrosion characteristics. The fourth alloy with mixed Sb and Bi additions has good fine grain structure and mechanical characteristics, but exhibits the highest corrosion rate.