Low-Cyclic Fatigue Behavior of Peak-Aged Mg–Nd-Based Alloy

In low cycle fatigue, Mg–Nd based alloys exhibit initial cyclic hardening and then softening. The cyclic hardening and softening behaviour of a peak-aged Mg–Nd-based alloy has been studied using transmission electron microscopy. The initial cyclic hardening is attributed to the increase of dislocation density and interaction of dislocations with nano-scale precipitates. The shearing of dislocations through precipitates and the transformation of precipitates in different stages of fatigue are responsible for the cyclic softening. The competing hardening and softening mechanisms present throughout the entire fatigue process. Hardening mechanism dominates in the very beginning of cyclic loading while softening takes over after certain numbers of cycles, say ~ 350 cycles.