PNNL

Abstract

Previously, results for CVD-SiC joints created using solid state displacement reactions to form a dual-phase SiC/MAX phase irradiated at 800°C and 5 dpa indicated some extent of cracking in the joint and along the CVD-SiC/joint interface. This paper elucidates the origin of cracking by thermomechanical modeling combined with irradiation-induced swelling effects using a continuum damage approach with support of micromechanical modeling. Three irradiation temperatures (400oC, 500oC and 800oC) are considered assuming experimental irradiation doses in a range leading to saturation swelling in SiC. The analyses indicate that a SiC/MAX joint heated to 400oC fails during irradiation-induced swelling at this temperature while it experiences some damage after being heated to 500oC and irradiated at the same temperature. However, it fails during cooling from 500oC to room temperature. The joint experiences minor damage when heated to and irradiated at 800oC but does not fail after cooling. The prediction agrees with the experimental findings available for this case.