Etude par Sonde Atomique Tomographique de la formation de nano ...
Etude par Sonde Atomique Tomographique de la formation de nano ...
Etude par Sonde Atomique Tomographique de la formation de nano ...
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tel-00751814, version 1 - 14 Nov 2012<br />
Chapter 4. Nitri<strong>de</strong> Dispersion Strengthened Steels<br />
Figure 4.15. Composition of <strong>nano</strong><strong>par</strong>ticles in MA NDS steel after hot extrusion<br />
(800°C) as a function of their sizes. Only Ti, N, Al, O and Fe, Cr (at.%) are shown. For<br />
com<strong>par</strong>ison the mean chemical composition is reported.<br />
a) b)<br />
Figure 4.16. Concentration profile drawn through Ti-N rich <strong>par</strong>ticle in MA NDS<br />
pow<strong>de</strong>r (consolidated by hot extrusion). (a) Profile has been drawn along evaporation<br />
direction. Ti, N, O species are shown together, Cr and Fe elements are also presented. The<br />
Guinier radius of the <strong>par</strong>ticle is 3.7 nm. (b) Profile showing a reduction of the re<strong>la</strong>tive<br />
atomic <strong>de</strong>nsity insi<strong>de</strong> of <strong>par</strong>ticle. Sampling size is 1.5×1.5×1 nm 3 .<br />
e) Annealing at 850°C/1h<br />
3D reconstruction of a small volume containing <strong>nano</strong><strong>par</strong>ticles in pow<strong>de</strong>rs annealed at<br />
850°C during 1h is shown on Figure 4.17 (a, b). Two distinct families of <strong>nano</strong><strong>par</strong>ticles are<br />
observed in this analyse: Ti-N-rich and Ti-Al-O rich <strong>par</strong>ticles. It must be mentioned that<br />
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