Near spherical α-Mg dendrite morphology and high damping of low-temperature casting Mg–1wt.%Ca alloy

A low-temperature casting method has been used to modify the microstructure of a Mg–1wt.%Ca alloy. A microstructure with nearly spherical regions of the primary α-Mg phase was obtained, rather than the more typical dendritic structure of the alloy cast at a higher temperature. A Dynamic Mechanical Analyzer was used to compare the damping properties of the alloy cast at a high temperature with those of the alloy cast at a lower temperature and with the damping properties of pure magnesium. The alloy cast at the lower temperature exhibited a higher damping capacity, although it was lower than that for pure magnesium. The damping is weakly dependent on strain amplitude at low strain amplitudes, but more strongly dependent on it at high strain amplitudes, which can be explained by the Granato–Lücke theory. The effects of microstructure on the damping properties of the Mg–1wt.%Ca alloy are discussed.