SYNTHESIS OF IRON ALUMINIDE-AL2O3 COMPOSITES BY IN-SITU DISPLACEMENT-REACTIONS

Composites consisting of an iron aluminide matrix with ceramic particl e reinforcements, such as alumina, could improve the high temperature strength without compromising the oxidation resistance. In this paper, the feasibility of processing Fe-A1 alloy/A1(2)O(3) composites by an in-situ displacement reaction between Fe-40at.%A1 and iron oxide, Fe2O 3, is investigated. Simple powder metallurgical processing was perform ed without resorting to any externally applied pressures or deformatio ns during the high temperature processing step. The microstructural fe atures of the composites are rationalized based on results from diffus ion couples. Preliminary mechanical properties such as fracture toughn ess, yield strength and hardness are determined and compared with the values obtained for monolithic iron aluminide-Fe-28at.%A1. Results sug gest that a significant improvement in the properties is needed and fu rther avenues for modifications, such as changes in the interface stre ngth and externally applied forces during processing, are suggested. ( C) 1997 Elsevier Science S.A.