Microstructures and tensile properties of Mg–8Gd–0.6Zr–xNd–yY (x + y = 3, mass%) alloys

Mg–8Gd–0.6Zr–xNd–yY (mass%) alloys which containing different Nd:Y mass ratio of 3:0, 2:1, 1:2 and 0:3 with a constant x + y = 3 were prepared by metal mould casting method, and the microstructure, aging behaviour and tensile properties have been investigated. The fibrous eutectic areas along the boundaries enlarge clearly in the as-cast alloys containing Y element, and the fine grain boundaries and dispersed precipitation are observed in the aged alloys. The Mg–8Gd–0.6Zr–2Nd–Y alloy exhibits notably age-hardening behaviour and the highest mechanical property. The ultimate tensile strength and yield strength of Mg–8Gd–0.6Zr–2Nd–Y alloy in the peak aged hardness are 293 and 221 MPa at room temperature, 248 and 191 MPa at 230 °C. The improvement of age-hardening response and tensile properties is mainly attributed to the quadrate-like stable Mg5RE precipitate, which forms readily and orderly in aged Mg–8Gd–0.6Zr–2Nd–Y alloy.