The tensile properties and high cyclic fatigue characteristics of Mg–5Li–3Al–1.5Zn-2RE alloy

The tensile and fatigue properties of the Mg–5Li–3Al–1.5Zn-2RE (LAZ531-2RE) alloy were presented. The alloy was prepared by hot extrusion after vacuum casting. The Portevin–Le Chatelier (PLC) phenomenon was observed during tensile deformation. The PLC effect was attributed to the dynamic interaction between solute atoms (Li) and dislocation movement. The abnormal negative strain rate sensitivity (SRS) in high strain rate regime can be explained by the dynamic strain ageing (DSA) mechanism. The higher ductility may be associated with finer-grained microstructure and Li addition. Fatigue crack propagation was characterized by striation-like features. The smaller spacing of fatigue striations and larger fatigue crack propagation zone at the lower total strain amplitude gave rise to a longer fatigue life.

Research highlights▶ The PLC phenomenon was observed during tensile deformation in LAZ531-2RE alloy. ▶ The negative SRS in high strain rate regime can be explained by the DSA mechanism. ▶ The higher ductility may be associated with finer-grained microstructure and Li addition. ▶ Fatigue crack propagation was characterized by striation-like features.