Nuclear Instruments and Methods in Physics Research B76 (1993) 96-98 North-Holland
NUNIB
Beam Interactions with Materials 8 Atoms
Mijssbauer and X-ray diffraction study of electrochemically Fe-Ni-Cr and Fe-Ni-Cr-P alloys
deposited
E. Kuzmann a, A. VCrtes a, F.Kh. Chibirova b, C.U. Chisholm ’ and M.R. El-Sharif ’ a Department of Nuclear Chemistry, Eiitvijs University, Budapest, Hungary b Kharpou Institute of Physical Chemistry, Moscow, Russian Federation ’ Glasgow Polytechnic, Glasgow, Scotland, UK
Miissbauer spectroscopy and X-ray diffractometry were used to study electroplated Fe-Ni-Cr and Fe-Ni-Cr-P alloys prepared under different circumstances resulting in a very wide composition. range. The X-ray diffractograms of deposits reveal amorphous-like or microcrystalline character of these materials. There are significant differences among the MGssbauer spectra of electrodeposited samples of different composition. We have found that most of the low temperature Miissbauer spectra of electroplated alloys significantly differ from those recorded at room temperature. A new magnetically split component appears beside the paramagnetic part in the spectra of Fe-Ni-Cr-P alloys at 5 K. The magnetic transition takes place in a wide temperature interval.
1. Introduction Constant composition having thick Fe-Ni-Cr electrodeposit [1,2] has a remarkable industrial importance due to its corrosion resistance, good adhesion and attractive appearance. In our previous works [3-.5] it was shown that the microcrystalline Fe-Ni-Cr electrodeposited alloys containing more than 40% iron, consist of ferromagnetic and paramagnetic phases. There are significant differences among the MGssbauer spectra of electrodeposited samples of different composition. The main phases of Fe-Ni-Cr and Fe-Ni-Cr-P coatings with lower iron concentration showed paramagnetic behavior at room temperature. The aim of the present work was to get further information about the structure of Fe-Ni-Cr and FeNi-Cr-P electrodeposited alloys by measuring the temperature dependence of their MGssbauer spectra between 4 to 300 K. X-ray diffractometry was also used for the investigation.
2. Experimental The samples electrodeposited onto Cu substrate were plated from electrolyte consisting of 0.8 M CrCl,, 0.2 M NiCl,, 0.3 M FeCl,, 0.5 M NH&l, 0.5 M NaCl, 0.15 M H,BO, or 0.2 NaH,PO, (for samples 9-12) and 0.2 M glycine (for samples 5-12) or 500/O (V/V) dimethylformamide (for samples l-4) and H,O at 25°C. 0168-583X/93/$06.00
The composition of samples was determined by electron microprobe analysis. Table 1 shows the preparation conditions and the composition of samples. X-ray diffractograms of electrodeposites were recorded by computer controlled DRON-2 diffractometer using Co K, radiation and beta filter. MGssbauer spectra of samples were measured in transmission geometry in temperature interval between 4 and 300 K. The measurements were performed on samples from which the copper substrate was removed electrolytically using phosphoric acid solution. 5 x lo9 Bq activity 57Co(Cr) source provided the gamma rays. Isomer shifts are given relative to alpha iron.
3. Results and discussion Fig. 1 shows an X-ray diffractogram typical for high Fe containing samples. The lines in the diffractogram are very broad and diffuse and they are centered around the positions expected for fee phase. This can reflect microcrystalline character of the electrodeposited alloy with very fine grain size. This result is the same as was found previously in the case of electrodeposited alloys plated onto griphite [3]. However, the diffractograms of P containing samples are very similar to those of rapidly quenched amorphous alloys. Massbauer spectra of electrodeposited Fe-Ni-Cr and Fe-Ni-Cr-P samples exhibit a large variety depending on the production parameters or the composition. The room temperature spectra of the samples are demonstrated in our previous paper [5].
0 1993 - Elsevier Science Publishers B.V. All rights reserved
E. Ktrzmann et al. / E~ectrochem~cally deposited Fe-IV-G
Fig. 1. X-ray diffractogram of Fe-41.9Ni-16.8Cr posited alloy.
97
alloys
electrode-
-4
0 vimm/s)
I
Fig. 3. Mijssbauer spectra of Fe-24.7Ni-33.2Cr electrodeposited alloy, recorded at 300 K (a), 225 K (b), 77 K (cl and 5 K (d).
Massbauer spectra, taken at temperature of liquid nitrogen and liquid helium, of deposites containing 40-50% Fe (samples l-4)correspond to those recorded at room temperature. No new components appeared in these spectra at temperature as low as 5 K. On the
Fig. 2. MGssbauer spectra of Fe-15Ni-47Cr electrodeposited alloy, recorded at 300 K (a) and at 77 K (b).
Table 1 Characterization
of samples Cathode potential [VI
PH
IlO.
1 2 3 4 5 6 7 8 9 10 11 12
-1.2 -1.5 - 1.5 - 1.7 - 1.8 -1.5 - 1.8 - 1.8 - 1.5 - 1.35 - 1.5 -1.5
1.6 1.6 1.6 1.6 1.4 1.4 1.6 07 0.33 0.33 0.33 0.33
Sample
Plating time [h]
Current [Al
2 1.75 2 19 2 4 4 2 2 5 4 2
0.08-0.11 0.16-0.23 0.14-0.31 0.28-0.32 0.46 0.24-0.37 0.67-0.91 0.70- 1.05 0.35 0.31-0.38 0.41
Composition [wt%] Cr
Fe
Ni
1.79 9.25 13.66 16.82 81.2 33.2 28.0 47.0 43.8 4.0 25.0 51.0
43.7 50.9 45.95 41.32 13.6 42.1 35.2 37.9 30.1 37.0 13.0 26.0
54-51 39.85 40.49 41.87 5.3 24.7 36.8 15.0 18.7 39.0 43.0 6.0
P -
17.5 19.0 19.0 16.0
E. Kuzmann et al. / Electrochemically deposited Fe-Ni-Cr
98
0
-4
alloys
--T-T?-
4
v(mm/s)
vlmmk)
Fig. 4. Mijssbauer spectra of Fe-39Ni-4Cr-19P, 77 K (a) and at 5 K(b).
recorded at
other hand, the low temperature spectra can also be understood taking into consideration the effect of the alloying elements in the neighborhoods of iron atoms by the methods worked out by us [6,7]. Consequently, it strongly supports that these electrodeposits can be considered as homogeneous alloys of solid solution having random binomial distribution of alloying elements. We have found that most of the low temperature Mijssbauer spectra of electroplated alloys significantly differs from those recorded at room temperature. This is illustrated in figs. 2-6. In the case of sample Fe-47Cr-15Ni the Mijssbauer spectrum reveals the appearance of a new magnetically split component at 77 K (fig. 2b) compared to the room temperature spectrum in which only paramagnetic component exists (fig. 2a). The spectra of sample Fe24.7Ni-33.2Cr (fig. 3) well illustrate that the magnetic
Fig. 6. Mijssbauer spectra of Fe-6Ni-SlCr-16P electrodeposited alloy, recorded at 77 K (a) and at 5 K (b).
transition takes place in a wide temperature range. Similar observations have often be obtained with amorphous alloys [81. The phosphorus containing electrodeposits exhibit only paramagnetic Mossbauer spectra even at 77 K (figs. 4a, 5a, 6a). However, a new magnetically split component appears beside the paramagnetic part in the spectra of Fe-Ni-Cr-P alloys at 5 K (figs. 4b, Sb, 6b). The relative intensity of magnetic component varies with the concentration of alloying elements in the samples. The paramagnetic and ferromagnetic components can be associated with different phases in these samples. Consequently, the low iron concentration and the phosphorus containing electrodeposits also consist of two main phases similarly to that found in the case of high iron concentration samples 13-51.
References ._.I
,;.
-
--A.f cl
4
0
4
vimmk)
Fig. 5. Mijssbauer spectra of Fe-43Ni-25Cr-19P electrodeposited alloy, recorded at 77 K (a) and at 5 K (bl.
[l] A. Watson, C.U. Chisholm and M.R. El-Sharif, Trans. Inst. Met. Finish 60 (1986) 149. [2] A. Watson, CU. Chisholm and M.R. El-Sharif, Trans. Inst. Met. Finish 64 (1988) 34. [3] A. Vertes, A. Watson, C.U. Chisholm, I. Czako-Nagy, E. Kuzmann and M.R. El-Sharif, Electrochim. Acta 32 (1987) 1761. [4] E. Kuzmann, I. Czak&Nagy, A. VCrtes, CU. Chisholm, A. Watson, M. El-Sharif, J. Kerti and G. Konczos, Hyp. Int. 45 (1989) 397. [5] E. Kuzmann, A. Vertes, C.U. Chisholm, A. Watson, M. El-Sharif and A.M.H. Anderson, Hyp. Int. 54 (19901 821. [6] E. Kuzmann, R. Oshima and F.E. Fujita, Proc. CAME, Jaipur, 1981, p. 553. [7] S. Nagy, E. Kuzmann, A. VCrtes, G. Szabd and G. Konczos, Nucl. Instr. and Meth. B34 (1988) 217. [8] CL. Chien and R. Hasegawa, Phys. Rev. B16 (19773 3024.