Damping capacities and microstructures of magnesium matrix composites reinforced by graphite particles

Magnesium matrix composites reinforced by graphite particles were fabricated using stir casting with graphite particle size of 50 μm and graphite particle volume fractions of 5%, 10%, 15% and 20%, respectively. A dynamic mechanical analyzer was used to measure the damping capacities of as-cast composites. The experimental results reveal that the graphite particles play an important role on the damping capacities of as-cast composites. The strain amplitude independent damping of as-cast composites increases significantly as the graphite particle volume fraction increases from 0% to 15%, but decreases when the volume fraction exceeds 15%. The damping values of as-cast composites rise slowly with increasing temperature from room temperature to 125 °C, and have no obvious change with increasing temperature from 125 °C to 250 °C, but rise rapidly with increasing temperature from 250 °C to 400 °C.