Microstructural evolution and mechanical properties of Mg-5Y-5Gd-<Emphasis Type="Italic">x</Emphasis>Nd-0.5Zr magnesium alloys at different states

The microstructural evolution and mechanical properties of Mg-5Y-5Gd-xNd-0.5Zr magnesium alloys at different states were studied. The results reveal that island compounds at the grain boundaries of the as-cast alloys mainly were Mg24Y5, Mg41Nd5, and Mg5Gd phases. After homogenization at 808 K for 24 h, the distribution of the island compounds became discrete and Mg5Gd phases mostly decomposed and dissolved. With hot extrusion, the grain size was refined to about 20 |ì m on average, and both the strength and elongation were greatly im-proved.After ageing at 523 K for 5 h, the strength of different extruded alloys largely increased but the elongation decreased. With the in-crease of neodymium content, the strength of the alloys at different states increased. The content ofneodymium element had an obvious ef-fect on the elongation of the designed alloys. In the designed alloys, the Mg-5Y-5Gd-2.2Nd-0.5Zr alloy exhibited the best combination prop-erties and its ultimate tensile strength, yield strength, and elongation could reach 380 MPa, 285 MPa, and 9.0%, respectively.