b'Figure 2. Multiscale microstructuralAccomplishments: debonding indicates (1) significant characterization of neutron-irradiatedThe microstructural characterizationsdifferential swelling between Cr and Cr-coated SiC specimen using opticalof the neutron-irradiated coatingSiC and (2) insufficient interface microscopy, SEM and TEM.specimens were completed in fiscaladhesion. Limited void formation year (FY) 2019. Low-magnificationin the irradiated Cr (Figure 2) and optical microscopy found thatXRD lattice constants suggests larger PVD is the most promisingswelling of SiC than of Cr, which processing route to produce aresults in tensile stress in the Cr radiation-resistant coating. Thecoating and explains the vertical electro-plated and plasma-sprayedcracks it experienced. A significant coatings experienced macroscopicfinding is that such radiation-cracking and delamination asinduced cracking was almost absent results of neutron irradiation.in the PVD TiN coating, which Therefore, the microstructures ofwarrants further investigation of this the PVD coatings were investigatedcoating for future research. Another in detail. Multiscale analysis ofimportant finding is that different the microstructure identified thegrades of CrN coating showed radiation damage processes: the PVDdifferent responses to neutron Cr coating exhibited irradiation- irradiation; in a coating with an induced surface cracking, which~10 nm Ti interlayer between the was associated with partial interfaceSiC substrate and the CrN coating debonding and cracks propagating(Figure 3), the number of radiation-vertically to the coating/substrateinduced cracks was reduced. This interface (Figure 2). The interfacialresult implies that a ductile interlayer 88 2019|AFC ACCOMPLISHMENTS'