The effect of β′ precipitates on mechanical properties and damping capacity in the Mg–Gd alloy

Abstract

In this work, the effect of β′ precipitates on mechanical properties and damping capacity in Mg–10Gd alloys were investigated systematically. The results show that compared with the as-extruded alloy, the aged alloy has a higher strength and damping capacity due to large number of nano-β′ precipitates. After aging treatment, the ultimate yield strength and ultimate tensile strength increase obviously, and the damping capacity is improved, especially, in high strain amplitude region. After comparing the applied stress corresponding to the damping capacity test with the increment of yield strength contributing from β′ phases, the nano-β′ precipitates act as strong pining points in dislocations damping mechanism, which is not beneficial to improving damping capacity. However, the β′ phases/Mg interface will cause local strain. When theexternal stress reaches certain level, these local dislocations start to move, lead to the relationship between the strain amplitude and damping value fit the Granato-Lücke (G-L) dislocation theory for the aged alloys not well and enhance the damping capacity. Aging phases not only have great contribution on strength, but also have positive effect on damping capacity, so precipitate strength may become an effective strategy to moderate the contradiction between the strength and damping capacity.