ROUND-ROBIN ATOM-PROBE EXPERIMENT : PRELIMINARY RESULTS IN JAPAN

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ROUND-ROBIN ATOM-PROBE EXPERIMENT : PRELIMINARY RESULTS IN JAPAN

S. Nakamura

To cite this version:

S. Nakamura. ROUND-ROBIN ATOM-PROBE EXPERIMENT : PRELIMINARY RE- SULTS IN JAPAN. Journal de Physique Colloques, 1986, 47 (C2), pp.C2-459-C2-464.

�10.1051/jphyscol:1986270�. �jpa-00225704�

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ROUND-ROBIN ATOM-PROBE EXPERIMENT : PRELIMINARY RESULTS IN JAPAN S. NAKAMURA

I.S.I.R, Osaka University, Mihogaoka, Ibaraki, Osaka 567, Japan

Abstract

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A round-robin experiment *re to be carried out by 6 laboratories in Japan (Nishikawa; Tokyo Inst. Tech., Sakurai and Igata; Univ. of Tokyo, Ishikawa; Hitachi, Tanino; Nippon Steel Corp. and Nakamura; Osaka MT.) under the normal operating condition (T<lOO°K,.~lse fraction-75%~~ Pc10' torr).

Fe-Cr-Al and W-25%Re alloys, which are divided fran a single wire were chosen as the specimen materials. A prelimi~ry analysis of the W-Re alloy of the laboratory cxmemrd s h w the good agreeinent with the expecting value even if it was under different experimental conditions. However the apparent concentration of the Fee-Al alloy s h w different result and is found to depend on the haging gas (Ne) pressure even at the same pulse fraction and specimen temperature. The operating condition will be discussed to obtain accurate quantitative analysis of alloys in the atom probe.

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mwm1ON

There are many type of atcm prohes which are conventional linear type and the energy focusing type

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gated imaging type and magnetic deflection type. The atan-probe instrument analyses a very small volum of the specimen. How accurately dose the atan-probe spectrum represent the actual ampsition of this volum? At the 25th and 26th I F S , round-robin atan probe experiment have already been presented before. These round investigated a ternary Molybdenum based alloy and alloy containing Silicon. In some atan probe microanalytical investigation of hanogeneous alloys, the apparent concentrations of certain element have been found to differ fran the expected values. For quantitative atan probe analysis of Silicon-containing alloys, it appears that a pulse fraction of at least 15% is required and the analysis inside the central ring of low index poles should be avided./'/ To cleare the present status of relative and absolute accuracies of the instnnnent, we have a co-operative research of ten groups in Japan. Preliminary results of six groups have been sumnerized.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1986270

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JOURNAL DE PHYSIQUE

The all of the specimen, W-25%Re and Fe-Cr-Al alloys used in this investigation were divided f r m a single wire and were sent out to all participating laboratories.

Sharply-pointed FIM specimen of these alloys were to be prepared by the specified electroetching technique in 3-5%KOH solution at 3-6V A.C. for W-25%Re alloy and in HN03 (1)

+

^HCl(1)

+

HJ)(2) solution at 4-+3 +l .2-1.5V D.C. for Fe-Cr-A1 The analysis were to be carried out under the normal operating condition of the laboratory concerned, which is indicated in Table. Co-operated groups and the instrument are shown in Table 1.

Table 1. Co-operative groups

Group Instrument

A Nishikawa et al: Poschenrieder-type Tokyo Inst. Tech.

B Sakurai et al: Poschenrieder-type Univ. of Tokyo

C Nakamura et al: Canbined linear and Osaka Univ. Poschenrieder-type D Igata et al: Magnetic deflection type

Univ. of Tokyo

E Ishikawa et al: Poschenrieder-type Hitachi

F Tanino et al: Poschenrieder-type Nippon Steel Corp.

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RESULTS AND DISCUSSION i) W-25%Re

A typical m s s spectrum for a W-25%Re alloy, showing the mass-to-charge range of 40-70 a.m.u. is exhibited in Fig.1. Fine structure of two major peaks located near 46 and 61 a.m.u. are clearly visible. W and Re appear in bth the i - 3 a n d t 4 . ionization states. Even using the linear flight tube (2m long), all isotope of

~e&*and W"'- be distinguished from one another at low pulse fraction and with 511s resolution timer. A s u n a ~ ~ y of the results fran matrix of W-25%Re alloy is shown in Table 2. The experimental composition of W-25%Re alloy show goad agreement with the naninal canposition of that. Re*'/~e~~ratios were 2.3% to 6 .l %. These results differ from other works which exhibited no ReAcat any case of W-lOat%Re alloys 'z'.

Only B group detected R@ions. Fig.2 shows a Re integrate profile of W-25%Re alloy.

The slope of the integrate profile is indicating that Re atoms are distributed uniformly.

ii) Fe-Cr-Al alloy

Sane precipitates, which may pssibley be TiN, were observed by optical microscope.

A h a X X g y dispersive X-ray (EDX) spectrum in the mtrix of alloy shows quit uniform

concentration of three elements Fe, Cr and Al. The peak height ratio of EDX spectra in the matrix were Fe:Cr:Al = 10:6:1. The many precipitates of Ti and Si were also observed by E13X spectrum. A typical mass spectrum of Fee-Al alloy by the linear flight tube mode is exhibited in Fig.3. Major peaks 56Fe2+, 57Fe2*, 5 3 e t , 52~e"

and 27A12*are clearly distinguished. 2 7 ~ 1 ' ~ , 54~e'~and 54k2'could not be separated even using the poschenrieder type mode, so that the mass-to-charge ratio of 27Alt+,

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handbook value of natural isotogic abundance. Number of atom 54Fe2+and 54Cr2'are 17 and 2 respectively then 27A1 is 14. Thus a t d c concentration ratio Fe:Cr:Al = 301 : 1 1 1:68. Other datas were also estimated frcm the same maner. A sunmary of the experimental dabs is shown in Table 3. Cr and Al integrate profile through the alloy rrratrix were uniform. In Table 3, the concentration of Al atom were disagree with one another even at the same exprimental conditions. The apparent concentration of Al a t m in the matrix decreased with gas pressure of Ne as shown in Table 4. The background pressure always held at about 10"~torr. A possible reason is as following; Ne gas atcms of kinetic energy 312 kTgas + 1 121X F2 collide with the surface atcm to which they can transfer a considerable fraction of thixe energy.

The energy transfer to Al atcm should be the most efficient canparing with other element in the matrix, because of the lawest mass number. Field evaporation of W and MO occurs in neon at slightly low fields than in vacuum or in helium when the inccming imaging gas molecules which have dipole attraction energy colide with surface a t m (31. Thus a selective D.C. field evaporation of Al a t m may give rise to a systematic error in the spectrumr,

Table 2. A sunanary of the results on the m e a s m t s of canposition in W-25%Re under different experimental conditions.

Group Number of atoms detected A t d c ampsition Conditions

~ 3 * R ~ ~ ~ Rehi- R ~ ~ Re ' : W

C 1986 204 664 30 24.1 75.9 P£ = 7%

T- 50K-,o 2 X 10 torr D

- - - - - - -

^-

- ---

24.5 75.5 Magnetic

deflection type

torr

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JOURNAL DE PHYSIQUE

Table 3. A sumnary of the experimental results on the m e a s ~ t s of ampsition in Fe-Cr-Al alloy under different experimental conditions.

Group Number of atans detected Atcmic canposition Conditions

Fe CS Al Fe:Cr:Al

Table 4. The experimental canposition of the same tip of F e e - A l alloy under different Ne gas pressure.

Ne gas pressure Fe(at%) -(at%) Al(at%) other (P.€=16%)

Vacuum_:,,

1. 2 X 1 0 t o m 57.5 26.4 14.1 2.0

Vacuum:

5. 2 X 10*"tom 57.8 25.3 14.1 2.8

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1 L

0 NUMBER OF ATOMS ¹²⁰⁰

Fig. 2

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The Re integral profil £ran W-25%Re alloy (B g r o u p )

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JOURNAL DE PHYSIQUE

10 15 28 25 30 35 48

MASS-TD-CHhRGE RATIO

( C group ) Fig. 3

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A typical mass spectrum of Fe-Cr-Al alloy taking in vacuum 2 X 10"~torr, employing 7% of pulse fraction and T--50°K, the fligh tube is linear type.

lhis work was partly supported by a Grant-in Aid for Co-operative Research from The Ministry of Education, Science and Culture.

/l / M.K.Miller and G.D.W.Smith, J. Vac. Sci. Technol. 19 ( 1 981 ) 57.

/2/ R.Herschitz and D.N.Seidnan, Acta Metall.

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⁽¹^98% ^{1 1}41.

431 0.Nishikawa and ~.~.I&ller, J. Appl. Phys. 3 (1964) 2806.