The strain-amplitude-dependent and strain-amplitude-independent damping capacities of a cast AZ91 magnesium alloy as functions of its age-hardening response induced by continuous precipitation have been investigated. The damping capacities of the AZ91 alloy exhibited a decreasing tendency in the order of solutionised, underaged, overaged, and peak aged states in the strain-amplitude-dependent region, whereas they increased continuously with aging time in the strain-amplitude-independent region. In view of the microstructural evolution during aging, the lower Al concentration in the α-(Mg) matrix and the lower number density of continuous precipitates are thought to be responsible for the better damping capacities of the AZ91 alloy in the strain-amplitude-independent and strain-amplitude-dependent regions, respectively.
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