Effect of Process Parameters on Mechanical and Corrosion Properties of Twin-roll Cast Mg-2Y-1Zn Magnesium Alloy

Abstract

Magnesium and its alloys have gained utmost attention as potential lightweight structural materials owing to their low density. However, the application of magnesium alloys is still limited by their low strength and poor corrosion resistance compared to aluminum alloys. Recently, Mg-RE-Zn alloys have shown good mechanical and corrosion resistance by forming long period stacking ordered (LPSO) phase. In the present study, Mg-2Y-1Zn (at. %) alloy was cast by horizontal twin-roll casting (TRC) process. The cast strips were processed through hot-rolling and analyzed for their mechanical properties and degradation behavior. The tensile behavior of the alloy showed improved mechanical property with higher preheating temperatures. Electrochemical and immersion tests indicated that the corrosion resistance was enhanced by higher preheating and annealing temperatures. The SKPM measurement revealed that the LPSO phase acts as a micro cathode to form galvanic couple with the alpha Mg which dominated the corrosion mechanism. The alloy showed its unique microstructure when solution heat-treated and the corrosion resistance was greatly improved by forming dense surface film.