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

tel-00751814, version 1 - 14 Nov 2012
Chapter 2. Materials, experimental and simulation techniques
(c) Deconvolution of overlap between 64CrN 2+ and 64TiN 2+ is conducted due to
natural abundances of Cr and Ti in agreement with the procedure discussed above
(for 64TiO 2+ /64TiN 2+ or 54Cr 2+ /54 Fe 2+ ).
Figure 2.13. Mass spectrum of nitrided NDS steel after annealing at 700°C/1h by
LAWATAP. Interval from 23 to 36 amu is shown.
c) Methods for APT data treatment
The data treatment procedure, in general, is similar for all materials and consists of
several steps:
Number of atoms
3000
2500
2000
1500
1000
500
(a) Measurement of the global chemical composition of the analysed volume;
(b) Investigation of solute distributions in analysed volumes. If clusters are not visible
(simply by eyes), then statistical tests are used. The assumption of a random distribution of
solute atoms (Cr, Ni, Mn, W, Si, etc.) is tested using the statistical test described in Appendix
3-a. Two results are possible:
0
(i) Statistical test confirms that the distribution of solute atoms in the analysed
volume is random. In this case the analysed volume is considered as a part of
matrix.
48Ti 2+
50Cr 2+ -50Ti 2+
52Cr 2+
53Cr 2+
54Cr 2+ - 54Fe 2+
55Mn 2+
56Fe 2+
57Fe 2+
58Fe 2+ - 58Ni 2+
23 24 25 26 27 28 29 30 31 32 33 34 35 36
Mass-over-charge ratio (amu)
60TiN 2+ - 60Ni 2+
61TiN 2+ - 61Ni 2+
62TiN 2+ - 62Ni 2+
63TiN 2+
64CrN 2+
66CrN 2+
67CrN 2+
68CrN 2+
69