Effect of Zn Content and Solution Treatment on Damping Capacities of Mg–Zn Casting Alloys

Abstract

The effects of Zn content and solution treatment on the damping capacities of Mg–(0–6)%Zn casting alloys were investigated. In the as-cast state, increasing Zn content led to an increase in the volume fraction of the MgZn phase, and to the deterioration of the damping levels, both in the strain-amplitude-independent and strain-amplitude-dependent regions. The microstructural evaluation indicated that the increased Zn concentration in the α-(Mg) matrix and increased number of MgZn particles are responsible for the deterioration of the damping in the strain-amplitude-independent and strain-amplitude-dependent regions, respectively. The solution-treated Mg–6%Zn alloy exhibited better strain-amplitude-dependent damping than the as-cast one, but the tendency was reversed in the strain-amplitude-independent region. The dissolution of the MgZn phase and the correspondingly increased Zn concentration in the α-(Mg) matrix after the solution treatment can explain the reversed damping behaviors in the strain-amplitude-dependent and strain-amplitude-independent regions, respectively.