  W-SiC composite material is a promising plasma-facing material candidate
alternative to pure W due to the low neutron activation, low impurity
radiation, and low tritium diffusivity of SiC while leveraging the high erosion
resistance of the W armor. Additionally, W and SiC have high thermomechanical
compatibility given their similar thermal expansion rates. The present study
addresses the synthesis and performance of compositionally graded W-SiC films
fabricated by pulsed-DC magnetron sputtering. Compositional gradients were
characterized using transmission electron microscopy (TEM) and
energy-dispersive X-ray spectroscopy (EDS), and crystallographic information
was obtained using electron diffraction and X-ray diffraction (XRD). Samples
were exposed to L-mode deuterium plasma discharges in the DIII-D tokamak using
the Divertor Material Evaluation System (DiMES). Post-mortem characterizations
were performed using scanning electron microscopy (SEM) and XRD. Electron
diffraction and XRD showed that the compositionally graded W-SiC films were
composed of polycrystalline W and amorphous SiC with amorphous W+SiC
interlayers. No macroscopic delamination or microstructural changes were
observed under mild exposure conditions. This study serves as a preliminary
examination of W-SiC compositionally graded composites as a potential candidate
divertor material in future tokamak devices.
