Abstract: The effects of graphite and SiC particles on the resultant damping behavior of the spray deposited high silicon alloy ZA27 were examined by Sound frequecy internal friction apparatus. The experimental results show that the damping capacities of the MMCs reinforced by SiC and Gr particulates are 3.90 and 3. 381 times more respectively than tha of the ascast alloy ZA27 at 30℃. After extrusion, the damping capacities of the MMCs improve a tittle, but the difference between them decreased a lot. The operative damping mechanisms were discussed in ligh of the data obtained from characterization of microstructure.