Etude par Sonde Atomique Tomographique de la formation de nano ...

tel-00751814, version 1 - 14 Nov 2012
Chapter 1.Bibliography
during milling. Concerning Cr2N, the author does not give any conclusions indicating that
further study is needed. In the case of FeXN and TiH2, dissolution during 48 h occurs.
In case of NDS elaboration by mechanical alloying several advantages can be envisaged:
� At least several solutions for nitrogen incorporation during MA can be suggested
(in contrast to ODS production, where commonly, only Y2O3 is used). These
solutions can offer some additional advantages in term of stability, i.e. they can
be less stable and dissolution may occur more easily (in comparison to stable
Y2O3);
� Homogeneous dispersion of strengthening particles (well known attribute of
MA).
� Significant experience gained form ODS production.
IV.3. Partial conclusions
Nitride Dispersion Strengthened Steels can have different advantages and could be an
alternative to ODS, replacing oxides by a fine and dense dispersion of nitrides. NDS materials
have been already envisaged for nuclear application in 1980s. Taking into account options
suggested in the past and new possibilities that are available nowadays, dispersion of nitrides
inside Fe-Cr matrix can be achieved by two ways: plasma nitriding and mechanical alloying.
Characterisation of such kind of materials in as-recieved state (as well as at elevated
temperature and irradiation) is needed at all levels as almost no database is available at the
moment in comparison to ODS steel.
In the framework of the ANR aXtrem program, ferritic Fe-18CrWT NDS steels are
elaborated by both mechanical alloying and plasma nitriding methods. The aim of the current
work is to provide a systematic study of the microstructural evolution at each step of the
elaboration process (initial state and subsequent heat treatments up to 1000°C) by means of
Atom Probe Tomography.
The studied materials and experimental technique used in this program and Ph.D will be
described in the next chapter.
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