Microstructure and tensile properties of Mg-Zn-Gd casting alloys.

<title/> The effects of Gd additions to a Mg-3Zn based casting alloy on the microstructure and tensile properties at room and elevated temperature have been investigated. As cast microstructures of the Mg-Zn-Gd alloys consists principally of primary Mg and Mg-Gd-Zn phases. The maximum tensile strength at both room and 175°C was found to occur at 1-2%Gd, while the elongation was continuously reduced by increasing Gd content. The ultimate tensile strength of 1-2%Gd containing alloys was comparatively high (∼150 MPa) at 175°C. The tensile creep resistance was remarkably enhanced by the Gd additions, presumably due to the formation of Mg-Gd-Zn phases. Creep deformation of only ∼0·5% was observed after 200 h (175°C and 50 MPa) in the case of 3%Gd. It was found that hot cracking resistance was slightly reduced at 1-2%Gd but recovered at 3%Gd. No significant change of fluidity was found with respect to the Gd content. [ABSTRACT FROM AUTHOR]