Characterization of Fiber-Matrix Interface Degradation in a Metal Matrix Compositte

The fracture and failure of fiber-reinforced composites are known to be strongly influenced by the properties of the fiber-matrix interface zone. Since these properties may be altered during processing, or may suffer degradation during service, the quality control of interface zones through nondestructive evaluation techniques is highly desirable. The overall properties of fiber-reinforced composites are related to their microstructure. In particular, the velocity of the average waves that can be transmitted in these materials depends on the elastic moduli and the densities of the constituents as well as the properties of the fiber-matrix interface. Thus, the interface conditions can, in principle, be determined from the measurement and analysis of wavespeeds in these materials. However, in practice, this is not a straightforward exercise due to the fact that the relationship between the overall and microstructural properties of a composite are in general nonlinear and thus may lead to an amplification of measurement errors. It is nevertheless extremely important to develop the capability to monitor the integrity of the fiber-matrix interface, especially in high temperature applications where the composites must operate in harsh environments