Damping behavior of as-extruded pure Mg and Mg-Bi binary alloys

Based on cost-effective wrought Mg-Bi based alloy with high strength and ductility, this study investigates the damping properties of Mg-xBi (x: 3, 6, 9 wt.%) binary alloys at both ambient and elevated temperatures. The results reveal that as-extruded Mg-6Bi and Mg-9Bi alloys not only maintain adequate strength but also exhibit superior damping performance at room temperature compared to alloys with similar strength. The damping behavior of Mg-xBi binary alloys aligns with the Granat-Lücke dislocation pinning model, and their damping performance improves with increasing strain (ε). In comparison to as-extruded pure Mg, the addition of Bi significantly enhances high-temperature damping properties. The high-temperature damping behavior of Mg-xBi binary alloys is consistent with the viscoelastic relaxation mechanism, with damping performance decreases as vibration frequency (f) increases. Notably, when f exceed 5 Hz, the influence of frequency on damping performance becomes negligible. The P₁ peak observed in the damping curves of Mg-xBi binary alloys demonstrates distinct thermal activation characteristics. The activation energies for the P₁ peak in as-extruded pure Mg and Mg-xBi alloys are 128.1 kJ/mol, 133.5 kJ/mol, 134.1 kJ/mol, and 138.3 kJ/mol, respectively.