Heat Resistance of Mg-Nd Based Casting Alloys Containing Gadolinium and Yttrium

Influences of Gd or Y addition on microstructures and tensile properties at room and elevated temperatures were investigated for T6-treated Mg-3%Nd-0.5%Zn-0.4%Zr casting alloys, on the basis of experimental results from X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, tensile and creep tests. Microstructures of the T6-treated alloys are characterized by recrystallized α-(Mg) grains containing various nano-sized precipitates such as Mg41Nd5, Zn2Zr3 and Zr particles. In T6 condition, most of added Gd and Y elements are dissolved in Mg41Nd5 precipitates rather than formation of new phases. Tensile properties and creep resistance of the Mg-3%Nd-0.5%Zn-0.4%Zr alloy are remarkably increased by the addition of Gd or Y, but their efficiencies are substantially the same.