Low-frequency damping properties of dual-phase Mg–xLi–0.5Zn alloys

Low-frequency damping capacities of dual-phase Mg–xLi–0.5Zn alloys with x = 6.0 (α-rich LZ60), 9.5 (LZ100) and 10.5 (β-rich LZ110) are studied by dynamic mechanical analyzer. Both LZ100 and LZ110 have a significant P1 peak but only LZ110 exhibits a significant P2 peak. LZ60 does not show any obvious internal friction peak and has the lowest tan δ value of high-temperature damping background (HTDB). Both P1 peak and HTDB of LZ100 are frequency dependent and thermal activated with their activation energy being 0.87 and 0.59 eV, respectively. The relatively low activation energy of HTDB for LZ100 is corresponding to the smaller atomic radius of Li atoms in Mg alloys which facilitates the dislocation climbing process at moderately high temperature. The strain amplitude dependence of tan δ value shows that, for LZ100 at room temperature, the critical strain is 3 × 10−5.