Microstructural characteristics of a fresh U(Mo) monolithic mini-plate: Focus on the Zr coating deposited by PVD

• Main Authors: Xavière Iltis, Doris Drouan, Thierry Blay, Isabelle Zacharie, Catherine Sabathier, Claire Onofri, Christian Steyer, Christian Schwarz, Bruno Baumeister, Jérôme Allenou, Bertrand Stepnik, Winfried Petry
• Format: Article
• Language: English
• Published: Elsevier 2021-08-01
• Series: Nuclear Engineering and Technology
• Subjects: U(Mo); Monolithic; Coating; Microstructure
• Online Access: http://www.sciencedirect.com/science/article/pii/S1738573321001327

Within the frame of the EMPIrE test, four monolithic mini-plates were irradiated in the ATR reactor. In two of them, the monolithic U(Mo) foil had been PVD-coated with Zr before the plate manufacturing. Extensive microstructural characterizations were performed on a fresh archive mini-plate, using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS), Electron Backscattered Diffraction (EBSD) and Focused Ion Beam (FIB)/Transmission Electron Microscopy (TEM) with nano EDS. A particular attention was paid to the examination of the U(Mo) foil, the PVD coating, the cladding/Zr and Zr/U(Mo) interfaces.The Zr coating has a thickness around 15 μm. It has a columnar microstructure and appears dense. The cohesion of the cladding/Zr and Zr/U(Mo) interfaces seems to be satisfactory. An almost continuous layer with a thickness of the order of 100–300 nm is present at the cladding/Zr interface and corresponds to an oxidized part of the Zr coating. At the Zr/U(Mo) interface, a thin discontinuous layer is observed. It could correspond to locally oxidized U(Mo).This work provides a basis for interpreting the results of characterizations on EMPIrE irradiated plates.