Cyclic Deformation of Rare-Earth Containing Magnesium Alloys

Cyclic deformation characteristics of a rare-earth (RE) element containing extruded Mg-10Gd-3Y-0.5Zr (GW103K) magnesium alloy were evaluated via strain-controlled low-cycle fatigue tests under varying strain amplitudes. Microstructural observations revealed that this alloy consisted of fine equiaxed grains and a large number of RE-containing precipitates. Unlike the RE-free extruded magnesium alloys, this alloy exhibited essentially cyclic stabilization and symmetrical hysteresis loop due to relatively weak crystallographic textures and reduced twinning-detwinning activities. The fatigue life of the present alloy was observed to be longer than that of the RE-free extruded magnesium alloys, which could also be described by the Coffin-Manson law and Basquins equation. Fatigue crack was observed to initiate from the specimen surface and crack propagation was basically characterized by fatigue striations.