LIQUID-PHASE SINTERED IRON ALUMINIDE-CERAMIC COMPOSITES

Iron aluminide intermetallics, which exhibit excellent oxidation and s ulfidation resistance, were found to be suitable as the matrix phase i n metal matrix composites, or the binder in hard metals (or cermets). In particular, ceramics such as TiB2, ZrB2, TiC and WC could all be li quid-phase sintered with an Fe-40 at% Al iron aluminide. The processin g and properties of such iron aluminide composites were assessed. Dens ity, hardness, bend strength, and fracture toughness data are presente d. Nearly complete densification was achieved for ceramic volume fract ions up to 60%. For iron aluminide-tungsten carbide composites contain ing 60 vol% WC, room temperature three-point bend strengths and fractu re toughnesses reached 1460 MPa and 20 MPa m(1/2), respectively. Consi stent with the high fracture toughness values, the fracture surfaces s howed evidence for ductile deformation of the iron aluminide binder. ( C) 1996 Elsevier Science Limited.