Pulse current induced damping enhancement in micron-submicron pure magnesium

Achieving synergistic enhancement of damping-mechanical performance in pure Mg remains a tough challenge. Electric pulse treatment has proven effective in regulating the microstructure of materials. This work comprehensively investigated the effects of pulse current on the microstructure and damping performance of pure Mg with micron-submicron grains, and revealed the mechanisms of damping enhancement associated with electric pulse treatment. The results suggest that pulse current effectively promotes dislocation disentanglement, thereby increasing the mobile dislocation density. In addition, pulse current facilitates dislocation slip and grain boundary relaxation in submicron samples, accompanied by the generation of high-density stacking faults. The microstructural evolution enhances the damping capacity of pure Mg. After electric pulse treatment, the strain amplitude independent damping (Q₀^–1) in samples I-Q-0 (7 µm), I-Q-20 (308 nm), and I-Q-60 (155 nm) increased by 17%, 11%, and 14%, while the strain amplitude dependent damping (Q_h^-1) increased by 5%, 11%, and 54%, respectively. The increment in strain amplitude independent damping capacity ΔQ₀^–1 is dominated by dislocations. Because pulse current can induce higher mobile dislocation density, contributing to greater energy dissipation and enhanced damping. Besides, the increment in strain amplitude dependent damping capacity ΔQ_h^-1 in micron I-Q-0 (7 µm) sample is also dominated by dislocation behavior. However, in submicron I-Q-20 (308 nm) and I-Q-60 (155 nm) samples, ΔQ_h^-1 is dominated by stacking faults rather than dislocations. Consequently, damping and mechanical properties are synergistically improved in micron–submicron pure Mg by electric pulse treatment.