Microstructure, mechanical properties and corrosion properties of Mg-Zn-Y alloys with low Zn content

The microstructure, mechanical properties and corrosion properties of Mg-Zn-Y alloys with low Zn content have been investigated in detail by the use of optical microscopy, SEM, mechanical properties testing and electrochemical measurement. SEM and optical microscopy observation firmly indicated that the grain size of as-cast and extruded alloys decreased with the increasing of Y content. Mechanical properties results have shown that the element Y could improve both tensile strength and elongation. The strengthening effect of I-phase is superior to that of W-phase while W-phase, however. has a better toughening effect than I-phase. Electrochemical measurements and immersion tests have indicated that the alloys with single secondary phase exhibited a better corrosion resistance than the alloys with two secondary phases. The alloy with single I-phase as second phase demonstrated the lowest corrosion rate. Mg-Zn-Y alloys with low Zn provided moderate strength, high ductility and excellent corrosion resistance, which open a new window for materials design, especially for biomedical application. (C) 2007 Elsevier B.V. All rights reserved.