Effects of solid solution elements on damping capacities of binary magnesium alloys

Effects of solid solution elements on damping capacities of four Mg-1at%X binary alloys (X = Zn, Sn, Ga, Al) with similar grain sizes are carefully investigated with pure Mg as comparison. The strain-amplitude-independent damping capacity of the solid solution alloy decreases with the higher lattice distortion caused by solute atoms, while the yield strength is just the opposite. The strain-amplitude-dependent damping capacity is affected by the lattice distortion, the stacking fault energy and the mixing enthalpy between solute atoms and Mg atoms, while the stacking fault energy is the dominant. The Mg-1at%Sn alloy exhibits the highest strain-amplitude-independent damping capacity, while the Mg-1at%Al alloy has the best strain-amplitude-dependent damping capacity at room temperature. When the temperature rises to about 100 degrees C, the Mg-1at%Zn alloy with the largest lattice distortion degree has the best strain-amplitude-independent damping. This may be related to the increase of the dynamic force for dislocation bowing caused by thermal activation.