Influence of Cr addition on microstructure of vacuum brazed NiCr-Cr3C2 composite coatings

Metallurgically bonded NiCr-Cr3C2 composite coatings modified by the additions of Cr were produced on a Ni-based superalloy substrate by high temperature vacuum brazing process. Effects of Cr addition on the microstructure, phases presented and the interfacial diffusion of the coatings have been investigated. Results show that the Cr additive consumed Si element to form Cr3Si and reduced the amount of brittle phase Ni3Si at the interface. The higher was the Cr addition in the coating, the thinner was the thickness of the secondary reaction zone, and the lower was the amount of the Ni3Si at the interface.