Metallurgical Characterization of the Interfaces and the Damping Mechanisms in Metal Matrix Composites.

Fiber reinforced metal matrix composites MMC are candidate structural materials for space applications because of their high specific modulus, low CTE, high electrical and thermal conductivity and high environmental resistance. Furthermore, the need for dynamic dimensional precision and weight savings in space structures suggests inherent material damping as an additional property requirement. A preliminary investigation indicates MMC exhibit improved damping with respect to conventional structural alloys of aluminum or titanium. In the present investigation, a graphite-aluminum composite P556061 has been selected to study the microstructural features and mechanisms responsible for damping in MMC. The objectives for this reporting period have been Establish a reliable test method and its limitations Develop reproducible damping test data at different frequencies and strain amplitude Thorough metallurgical characterizations of interfaces Suggest an operative damping mechanism in MMC and Recommendations for further investigations.