Low-cycle fatigue behavior of extruded Mg–10Gd–2Y–0.5Zr alloys

Abstract

The low-cycle fatigue properties of extruded Mg–10Gd–2Y–0.5Zr (GW102k) magnesium alloy have been studied and compared to those of conventional extruded AZ31 magnesium alloy. Typical post-fatigue microstructure and surface morphology features are presented for both the GW102k and AZ31 alloy. It is found that GW102k alloy contains a large amount of precipitated particles and possesses a relatively weak basal texture, which gives rise to near symmetric yield asymmetry. Different from AZ31 alloy, the GW102k alloy shows near-symmetric stress–strain hysteresis loops and marginal cyclic hardening. This symmetry significantly reduces tensile mean stress during low-cycle fatigue process. Due to the small reversible plastic zone size, the GW102k alloy shows rough faceted fracture surfaces in the fatigue crack propagation zone. Accordingly, the low-cycle fatigue life of GW102k alloy is found to be longer than that of AZ31 alloy.