Effect of Ag addition on microstructure and mechanical properties of Mg-14Gd-0.5Zr alloy

Microstructure and mechanical properties of the Mg-14Gd-0.5Zr (wt.%) alloy and Mg-14Gd-2Ag-0.5Zr (wt.%) alloy in homogenized, extruded and aged conditions have been investigated. Addition of 2% Ag enhances the tensile ultimate strength of the homogenized Mg-14Gd-0.5Zr alloy due to producing a larger strain field in magnesium crystal lattice. For the hot extruded alloys, the Ag-containing alloy shows a different type of texture, finer grains, higher hardness and a weak age-hardening response compared with the extruded Mg-14Gd-0.5Zr alloy, which are influenced by more Mg5Gd phases precipitating during extrusion in the Ag-containing alloy. The extruded Ag-containing alloy in peak-aged condition exhibit a lower yield strength due to a lower density of the prismatic β′ precipitate, while its better elongation is ascribed to the finer grain size and the basal precipitate.