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.