Development of high ductility magnesium-zinc-cerium extrusion alloys

A previous paper [I] showed that the ductility of extruded Mg-0.2%Ce alloy is higher than that of magnesium and other conventional magnesium alloys. However, the yield and tensile strengths of the Mg-0.2%Ce alloy were low. The addition of aluminum to the Mg-0.2%Ce improved its strength but significantly decreased its ductility [2]. This study shows that a small addition of zinc (about 2%) can significantly improve the strength of the Mg-0.2%Ce alloy (96% increase in yield strength to 135 MPa; and 32% increase in ultimate tensile strength to 225 MPa) with only a slight reduction in elongation (27.4% vs. 31%). With increasing Zn content, from 2% to 6%, the ultimate tensile strength of the Mg-Zn-Ce alloys increased, the yield strength remained the same, but the elongation decreased considerably. Electron probe micro-analysis (EPMA) and electron backscattered diffraction (EBSD) results showed that while Zn increased strength through solid solution strengthening, the Ce increased the ductility of these alloys through improvement in texture.