TEM Analysis of the Microstructure Evolution in Ion Irradiated Austenitic Stainless Steels

Austenitic stainless steels are widely used in nuclear power plants as internal structures of PWR. These steels are subjected to severe irradiation and temperature conditions. Understanding of microstructural changes of austenitic steels due to these conditions is an important task for safety and life-extension reasons. Ni ion irradiation on thin foils and in bulk is done in CSNSM-Orsay on commercial purity 316L and model FeNiCr alloy to a dose of 5 dpa at 450 degree C. These conditions are representative of several operational years. A detailed defect analysis (dislocation loops, cavities, induced phases) is performed by TEM techniques combination and discussed in the two alloys. TEM studies are associated with APT, detailed in an other paper. A special attention is ported on the differences in defects accumulation between both type of irradiated samples (thin and bulk). This work is done as a part of the FP7 European Collaborative project Perform60.