Influence of milling duration and aluminum pollution on the microstructure of Oxide Dispersion Strengthened

摘要

Oxide dispersion strengthened (ODS) steels are promising materials as cladding tubes for future nuclear reactors. They resist to swelling and have good mechanical properties at high temperatures and under irradiation thanks to a very fine nano-cluster (NC) dispersion. The usual process of their elaboration is a high energy milling of powders FeCrWTi and Y_2O_3 followed by thermo-mechanical treatments. Nevertheless, the process seems to be rather hard to control since the huge variations of mechanical properties observed in the literature. Previously, a new elaboration route inspired of reactive ball milling was developed on a very small milling device (FeCrW+YFe3+Fe2Ti+Fe2O3) where the crucial role of the milling parameters was highlighted. Two powders revealed different after milling remained different despite any post-milling heat treatment. The actual study proves the efficiency of the new procedure at large scale to elaborate ODS steels. From the production of different milling duration ODS steels, the role of titanium and aluminum contamination on NC dispersion is revealed. Even at a small content, aluminum is able to enter the NC composition causing their growth. Due to a competition between titanium and aluminum effect, the smallest and highest density NC distribution is obtained for an intermediate time of milling.