Effect of Interfacial Reaction on High Temperature Properties of Fe-Cr-Si Fiber Reinforced AC8A Aluminum Composites

Metallic fibers (Fe-Cr-Si) with an excellent high temperature strength are expected to be use as a reinforced material of the engine piston head. However, the high reactivity of Al with most metals has disturbed the use of metallic fibers in aluminum composites until now. In this study, the influence of the reaction products at the fiber/matrix interface on high temperature properties of the composites was investigated by different solution treatment conditions. It is found that hardness and strength increase with an increase the solution treatment temperature (Tst). Reaction products (Al-Fe intermetallic compounds) resulting from solution treatments were formed along the fiber/matrix interface at 773 K or higher. The composites without interfacial reaction products (Tst=763 K) showed excellent rotating-bending fatigue life at 573 K. The fatigue crack propagation in this composite occurred at the necking region of the metal fiber because no cracks were observed in the interfacial reaction products.