Brazing of ceramic-matrix composites to Ti and Hastealloy using Ni-base metallic glass interlayers

Carbon-carbon, carbon-silicon carbide, and silicon carbide-silicon carbide composites were vacuum brazed to Ti and Hastealloy X using Ni-base metallic glass braze foils (MBF-20 and MBF-30). Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) of the joints showed that compositional changes due to substrate dissolution led to secondary-phase precipitation which aided interfacial bonding although inter-laminar shear failure occurred within some composites. Residual thermal stresses in the joint led to hardness gradients; however, stress accommodation by the brazes prevented interfacial cracking. The peak Knoop microhardness in the joints was as high as 1165-1294 KHN.