Preparation of W–Cu functionally graded material coated with CVD–W for plasma-facing components

Abstract W–Cu functionally graded materials (FGMs) are designed to be a transition layer between CuCrZr bulk material and a W surface layer in plasma-facing components. In this study, a type of in-house developed ultrafine W–Cu composite powder has been used to fabricate a W–Cu FGM, which consists of three layers of W–10Cu, W–32Cu, and W–60Cu respectively. The sintered FGM has a homogeneous microstructure and a residual porosity of less than 3.3%. The W–10Cu side of the FGM has been coated with pure W using an optimized chemical vapor deposition (CVD) process with an increased deposition rate of 0.8 mm/h. The thickness of the coating is around 2 mm and the density is as high as 19.23 g/cm 3 . The columnar grain size of CVD–W at the end of deposition is approximately 20–50 μm in the direction parallel to the substrate and 1–1.5 mm in the direction perpendicular to the substrate. Compared with plasma-sprayed W–Cu FGM and W coating, the FGM and CVD–W developed in this study have a better microstructure, which is important for the thermal and physical properties of the components.