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 ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
tel-00751814, version 1 - 14 Nov 2012<br />
Chapter 3. Oxi<strong>de</strong> Dispersion Strengthened Steels<br />
In the hot extru<strong>de</strong>d condition, TEM characterization [6] of the microstructure shows that<br />
it is ma<strong>de</strong> of very fine grains or ‘‘fibres”. Grains are elongated in the extrusion direction<br />
(several microns in longitudinal direction and about 300 nm in thickness), as expected after<br />
such a treatment. In addition, a high number <strong>de</strong>nsity of dislocations, 10 14 -10 15 m -2 , is reported<br />
[6, 41]. Such <strong>de</strong>nsities have the same or<strong>de</strong>r of magnitu<strong>de</strong> as in tempered martensitic ODS<br />
[42].<br />
Different c<strong>la</strong>sses of oxi<strong>de</strong>s are observed [6, 7]: (a) located mainly on the grain boundaries<br />
with sizes from several tens of <strong>nano</strong>metres, (b) spherical <strong>nano</strong><strong>par</strong>ticles (R=1.85 nm and<br />
<strong>de</strong>nsity 8×10 22 m -3 ) homogeneously distributed.<br />
As bigger <strong>par</strong>ticles are mainly located at grain boundaries and have a low number <strong>de</strong>nsity<br />
(
Change language