Effect of extrusion temperature on microstructures and damping capacities of Grp/AZ91 composite

Magnesium matrix composite reinforced by graphite particles was fabricated using stir casting with graphite particle size of 50 μm and graphite particle volume fraction of 10%. The as-cast composite was extruded at 250 °C, 300 °C and 350 °C with an extrusion ratio of 12:1. The experimental results reveal that the extrusion temperature plays an important role on the microstructures and damping capacities. The aspect ratio of graphite particles increases as the extrusion temperature rises. Extrusion at 300 °C leads to the highest damping values in low strain region at room temperature. It also demonstrates the highest damping values at elevated temperatures when the strain is 4 × 10−5. In addition, there are two definite damping peaks in the damping-temperature curves which occur at about 150 °C and 350 °C, respectively.