Microstructural Characterization of Mg-TM (TM=Ni or Cu) - Y Alloys and their Mechanical Property

Abstract

Microstructure and mechanical property of the Mg-TM (TM=Ni or Cu) -Y alloys were investigated. Results revealed that Mg phase, Long period stacking ordered (LPSO) phase, and Mg2TM phase were formed in the Mg-TM-Y alloy around the composition ratios of TM and Y are 1:1 or 1:2. Tensile test clearly showed relationship between the mechanical property and microstructure in Mg-Ni-Y cast alloy. The 0.2% proof stress (σ0.2) of the Mg-Ni-Y cast alloy increase with the increasing solute elements contents, while the elongation decreases. This result indicated that the Mg-TM-Y alloy with the composition ratios of TM and Y are 1:1 or 1:2 have both high proof stress and appropriate elongation. It was suggested that the LPSO phase was appropriate strengthening phase in the Mg-rich region in the Mg-TM-Y alloy system. Basal texture of the LPSO and Mg phases was formed by hot-rolling in the sheet plane and the Mg2TM phase was dispersed in the Mg phase. The Mg97Cu1Y2 rolled sheet showed highσ0.2 about 350 MPa at room temperature. Furthermore, formation of an oxide film on the Mg-Cu-Y alloy was investigated at 973 K in air. As a result, it was suggested that the Y2O3 film was formed on the re-melted Mg-Cu-Y alloy surface as an incombustible oxide film.