Abstrakt
Magnesium matrix composites show improved wear resistance, enhanced strength and creep resistance in comparison with their monolithic counterparts, on the other hand keep low density and good machinability. Internal friction measurements are a suitable tool to detect changes in the microstructure of thermally or mechanically loaded composites.
Samples from pure magnesium reinforced with zirconia nanoparticles were thermally cycled between room temperature and increasing upper temperature of thermal cycle. After thermal cycling amplitude dependence of damping measured in terms of the decrement was measured.
Very high values of the logarithmic decrement are described to the poor binding between the matrix and ceramic nanoparticles. The influence of number of cyclic bending to fatigue on the damping behaviour of the same nanocomposite was determined at room temperature.
The measured decrease of the resonant frequency indicates a loss of stiffness during cycling. Crack deflection along an interface is followed by the separation of the particle/matrix interface.