Liquid-phase sintered iron aluminide-ceramic composites

Iron aluminide intermetallics, which exhibit excellent oxidation and sulfidation resistance, were found to be suitable as the matrix phase in metal matrix composites, or the binder in hard metals (or cermets). In particular, ceramics such as TiB2, ZrB2, TiC and WC could all be liquid-phase sintered with an Fe-40 at% Al iron aluminide. The processing and properties of such iron aluminide composites were assessed. Density, hardness, bend strength, and fracture toughness data are presented. Nearly complete densification was achieved for ceramic volume fractions up to 60%. For iron aluminide-tungsten carbide composites containing 60 vol% WC, room temperature three-point bend strengths and fracture toughnesses reached 1460 MPa and 20 MPa m(1/2), respectively. Consistent with the high fracture toughness values, the fracture surfaces showed evidence for ductile deformation of the iron aluminide binder. (C) 1996 Elsevier Science Limited.