Summary of TEM examination of deformed microstructures. A qualitative description of the observed microstructural features in the deformed microstructure after tensile tests at different temperatures is given. At low testing temperatures, below 400ºC, the deformed microstructure is dominated by high dislocation density at the interior of the grains due to efficient pinning of the nanoprecipitates. Features indicating a lower efficiency on the pinning of dislocations by precipitates, as testing T increases are the observed free dislocation regions and the formation of subgrain boundaries between regions of different densities of precipitates or region delimitating inhomogeneities, due to the different mobility of dislocations in each region. The described features can be found after deformation in the different conditions, but their proportion would depend on testing T. Further work on quantifying every type of microstructural feature is needed in order to determine the relative importance of every deformation mechanisms depending on T. The experiments were performed at CEMES (Toulouse, France) in a TEM JEOL-2010 and employing an straining sample holder with possibility of heating. The experiments were performed thanks to an accepted proposal presented by CIEMAT at the ESTEEM2 platform for use of European facilities. They were performed in collaboration with X. Mompiou (CEMES) and X. Malaplate (CEA) by the end of March 2016. The studied material was Fe14Cr ODS, heat J27 from CEA (Bar 1-3). The orientation of the specimens refered to the received bar is shown schematically in figure 9. Orientation R was selected for this set of experiments in order to be complementary to previous experiments from CEA on L direction. R1 200 400 600 R2 000 000 000 700 R3 200 400 - - - - R5 - 400 600 700 R7 - - - 600 650 700 L5 - - - - - 700 Internal strains were evaluated by in-situ synchrotron compressive tests at room temperature conducted at EDDI beamline at the storage ring BESSY, at the Helmholtz Zentrum Berlin (Germany). The high temperature tests were performed at PETRA III-DESY facility (Germany). The investigated material was the Fe14CrODS in as-received estate and aged at 700ºC/10000h. Cylindrical samples were machined along the extrusion direction and 3 mm discs were extracted from the compressed specimens suitable for TEM examination.
