| Summary: | Y2O3 has been regarded as an effective diffusion barrier in SiCf/Ni composites to block the violent interfacial reactions, however, its high intrinsic brittleness makes it susceptible to cracking and/or peeling off during the consolidation process, thereby destroying the blocking effect. In this work, the (Y/Y2O3)n multilayer with enhanced fracture toughness was fabricated on C-coated SiC fibers as diffusion barrier layer in SiCf/Ni3Al composites, achieving intact protection of the SiC fibers, which is superior to single C layer and C/Y2O3 dual-layer. The (Y/Y2O3)n multilayered diffusion barrier coating enables the tensile strength of the composite to reach ∼ 715 MPa at 900℃, which is ∼ 1.5 times higher than that of the composite with C/Y2O3 dual-layer. TEM investigation showed that the outermost Y2O3 sublayer in (Y/Y2O3)n multilayer reacted with nearby Ni3Al matrix to form YAlO3/Al2O3 bilayer products, which effectively inhibited the diffusion of Ni atoms to SiC fibers. The remained (Y/Y2O3)n multilayer first mixed to form oxygen vacancy-rich Y2O3-x compounds and then reacted with C coating to form fine and coarse YO0.7C0.3 sublayers nearby YAlO3/Al2O3 bilayer. The results suggest that constructing the toughened (Y/Y2O3)n multilayer as diffusion barrier coating should be a potentially effective strategy for inhibiting interfacial reaction in SiCf/Ni composites.
|
|---|
