Effect of heat treatment on fatigue life improvement of Mg-Gd-Zn-Zr alloy.

This work investigated the fatigue behaviors of Mg 96.32 Gd 2.5 Zn 1 Zr 0.18 alloy under both solution and aging conditions. The main microstructural difference between the two conditions is characterized by the dense β′ nano-precipitates under aging condition. The fatigue strengths are comparable under both conditions, whereas the fatigue lives at medium stress levels tend to be improved apparently under aging condition. The improved fatigue lives under aging condition are attributed to the dense β′ nano-precipitates, which delay the processes of crack initiation and early propagation. Under solution condition, fatigue damage exhibits a continuous pattern along the damage bands. However, under aging condition, fatigue damage shows a scattered pattern along the damage bands due to the pinning effect of β′ nano-precipitates and their inhomogeneous distribution. • Dense β′ nano-precipitates delaying the crack initiation and early propagation process. • Inhomogeneous distribution of β′ nano-precipitates influence the damage accumulation. • Fatigue damage showing a high concentration of oxygen. [ABSTRACT FROM AUTHOR]