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

tel-00751814, version 1 - 14 Nov 2012
Chapter 2. Materials, experimental and simulation techniques
nanoparticles.
(b) No Ni atoms are located at 30, 30.5, 31, 32 amu. Ni is not associated to
(c) TiN 2+ and TiO 2+ overlap between 30 and 33 amu is deconvoluted in accordance to
Ti natural abundances. The total number of ions at 31 amu (Xtotal), is equal to the number of
TiN (XTiN 3 ) and the first isotope of TiO (XSi 1 ). XTiN 3 can be estimated from two others TiN 2+
isotopes at 30 and 30.5 amu which represent respectively 8.0 and 7.3 %:
XTiN 3 = (XTiN 1 +XTiN 2 ) × 79.3/(8.0+7.3),
where XTiN 1 and XTiN 2 is a number of detected ions located at 30 and 30.5 amu. Then the TiO
isotopes located at 31 amu can be calculated as:
XTiO 1 =X total-XTiN 3 .
Similarly, the TiN and TiO overlaps at 31.5 and 32 amu can be separated.
(a) (b)
Number of atoms
80
60
40
20
27Al 2+
14N + -14Si 2+
29Si 2+
30Si 2+
46Ti 3+
47Ti 3+
48Ti 3+
49Ti 3+
50Ti 3+
0
13 14 15 16 17 18
Mass-over-charge-ratio (amu)
Figure 2.12. Mass spectrum of MA NDS steel after annealing at 850°C/1h. Intervals of
mass spectrum (a) from 13 to 18 and (b) from 22 to 32 amu are represented.
Concerning as-nitrided NDS steel, a mass spectrum of a powder after annealing at
700°C/1h is shown on Figure 2.13.
Number of atoms
The calculation of chemical composition of nanoparticles follows these assumptions:
(a) Only N atoms are located at 14 amu (no Si atoms);
(b) No Ni 2+ atoms are located at 30, 30.5, 31, 32 amu.
160
140
120
100
80
60
40
20
46Ti 2+
47Ti 2+
48Ti 2+
49Ti 2+
50Cr 2+ -51Ti 2+
52Cr 2+
53Cr 2+
54Cr 2+ - 54Fe 2+
0
22 23 24 25 26 27 28 29 30 31 32
55Mn 2+
56Fe 2+
57Fe 2+
Mass-over-charge-ratio (amu)
58Fe 2+ - 58Ni 2+
61Ni 2+
60TiN 2 - 60Ni 2+
61TiN 2+ - 61Ni 2+
64TiN 2+ - 64TiO 2+ - 64Ni 2+
62TiN 2+ - 62TiO 2+ -62Ni 2+
63TiN 2+ - 63TiO 2+
68