Diffusion bonding reactions between a SiC/SiC composite and two superalloys during joining by hot isostatic pressing

Abstract Diffusion reactions during solid state joining of a ceramic SiC/SiC composite to two superalloys, Hastelloy X and Incology 909, by hot isostatic pressing (HIP) have been investigated. The HIP pressure was 200 MPa in all joining cycles, and the temperature/dwell time were either 800°C/15 min, 900°C/1 h or 1000°C/ 1 h. The reaction zones formed consisted of a thin layer of carbides surrounded by several layers containing silicides and free carbon. The thickness of the reaction layers increased with increasing temperature, but were more affected by the composition of the alloy. With more carbide formers in the alloy, the thickness of the reaction layer decreased. The SiC composite was found to be considerably more prone to reactions with these superallys during HIP as compared to Si 3 N 4 under similar conditions.