Stability of micro structure in magnesium reinforced by nanoscaled alumina particles

Changes in the microstructure of Mg with a grain size about 1 μm and Mg reinforced by 1 vol.% Al2O3 nanoscaled particles due to thermal treatment are investigated by internal friction measurements. The internal damping was measured on bending beams at frequencies from 220 to 230 Hz. It is shown that the value of the logarithmic decrement is influenced by the specimen preparation as well as the by thermal treatment of specimens. Results are discussed on the basis of existing models. It is shown that the internal friction measurements can be used for non-destructive investigations of changes in the microstructure.