Brazing of reaction-bonded silicon carbide and Inconel 600 with an iron-based alloy

The objective of the present work was to join reaction-bonded silicon carbide to Inconel 600 (IN600, a nickel-based superalloy) for use in high temperature applications by brazing with an Fe-20wt% alloy. This joining method resulted in the molten filler metal reacting with the IN600 to form a Ni-Fe-Si solution, which in turn formed a liquid with the free silicon phase of the RBSC. This liquid reacted vigorously with the SiC component of the RBSC to form low melting point phases in both starting materials and chromium carbides at the metal-ceramic interface. By using solution thermodynamics, it was shown that a Ni-Fe-Si liquid with equimolar nickel and iron contents and silicon content of less than 30 at% Si will decompose α-SiC at the experimental brazing temperatures; it was also shown that these predictions agree with the experimentally observed microstructures and line composition profiles.