Microstructural control and reinforcement mechanism of the Mo and B inserts in the SiCf/SiC composites/Ni-based superalloy joint

Abstract

The SiCf/SiC composites/Ni-based superalloys dissimilar joining encountered the problem of huge thermal mismatch and uncontrollable interfacial reactions. Two novel composite fillers were designed for the dissimilar joining. An AuCuTi/Mo/AuCuTi filler enabled a complete hindrance on the atomic exchange by a 50 μm Mo interlayer and an effective stress relief by multiple layers of the ductile (Au, Cu) solid solution and rigid Mo insert. Furthermore, the addition of B introduced an extra dimensionality to control the diffusion of interstitial atoms (Ni, Cr, and Si) and some TiB whispers to add extra nucleation sites for the Ni-compounds, by which way an easier and more accurate method to control the distribution of metallic atoms were obtained. The load-carrying of joints increased by 17.7% when using an AuCuTiB/Mo/AuCuTiB filler, because of the distribution of intermetallic compounds was homogenized and fined, and the interfacial region changed from Ti3SiC2 to TiC + Ni-compounds.