Decommissioning of TEXTOR: properties of the Inconel liner

The final shut-down of Tokamak Experiment for Technology Oriented Research in year 2013 created unique opportunities for multi-directional studies of in-vessel components. A set of specimens from the Inconel liner parts was collected in order to assess material properties after 26 years of exploitation. The metal surfaces were covered with up to several m thick co-deposits rich in boron, carbon and silicon. Detailed examination of the co-deposits and near-surface structure of Inconel performed with Transmission Electron Microscopy (TEM) revealed: (i) stratified character of the deposits; (ii) a ∼200 nm thick layer identified as NiSi2 phase at the interface between the deposit and Inconel substrate; (iii) changed Inconel surface layer. TEM studies of the Inconel structure revealed its polycrystalline character with a mean grain size, low dislocation density and a significant number of heterogeneously distributed primary carbides.