Damping properties of aluminum matrix–fly ash composites

The damping properties of the hollow sphere fly ash/6061Al composites with various reinforcement diameters and with about 40 vol.% porosities (enclosed within the hollow sphere fly ash particles) have been measured by using the forced vibration mode and the bending–vibration mode on the multifunctional internal friction apparatus. The results indicate that the damping capacity of the fly ash/6061Al composite with smaller reinforcement diameter is higher than that with larger reinforcement diameter in both vibration modes. In the bending–vibration mode, there is a more significant increase in the damping capacity of the as-received commercial 6061Al due to the addition of fly ash particles and the damping capacities of the fly ash/6061Al composites can reach (2–3) × 10− 2, which is more than two times of the maximum values measured in the forced vibration mode. But this phenomenon has not been found in the as-received 6061Al. The related mechanism has also been discussed.