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Submitted on 1 Jan 1971
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EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF IMPURITIES ON THE CURIE
TEMPERATURE OF IRON
S. Stoelinga, A. Grimberg, R. Gersdorf, G. de Vries
To cite this version:
S. Stoelinga, A. Grimberg, R. Gersdorf, G. de Vries. EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF IMPURITIES ON THE CURIE TEMPERATURE OF IRON. Journal de Physique Colloques, 1971, 32 (C1), pp.C1-330-C1-331. �10.1051/jphyscol:19711110�. �jpa-00213926�
STRUCTURE EL ECTRONIQUE D M L LIA GES
EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF IMPURITIES ON THE CURIE TEMPERATURE OF IRON
STOELINGA S. J. M., GRIMBERG A. J. T., GERSDORF R. and D E VRIES G.
Natuurkundig Laboratorium der Universiteit van Amsterdam, the Netherlands
R6sum6. - On a mesure la variation de la temperature de Curie du fer causee par des impuretks dissoutes, en fonc- tion de la concentration. Dans presque tous les 27 systemes consideres la dkpendance de la concentration etait linkaire pour des titres de moins de 1 %.
Abstract. - The shifts of the Curie temperature of iron due to about 1 at % and less of 27 different dissolved ele- ments has been measured. Almost all the investigated alloys show a linear dependence on concentration.
Introduction. - Among others M. Fallot ( E 1937) djd many accurate measurements of the Curie tem- perature of binary alloys of iron with roughly 1-2 at %
and more of different elements [ I , 2, 3, 4, 5, 61. We measured the shifts for low concentrations up to 1 a t %. In this range the shifts proved to be linear in the concentration in almost all cases. As many diffe- rent systems as reasonably possible were investigated.
They were alloys of Fe with : Ti, V. Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Mo, Ru, Rh, Pd, In, Sn, Sb, W, Re, Os, Ir, Pt, Au, Al, Si, Be.
Lacking an adequate theoretical model we inves- tigated this large number of alloys in order to find trends in behaviour.
Experimental. - Our samples were in the shape of rings with an outer diameter of 1 cm, an inner diameter of 0.5 cm and a thickness of 0.1 cm. Two rings, one of pure iron and one of the alloy were measured together in a copper block that served as a constant temperature housing and had a fairly large mass in order to get a smooth variation of the temperature.
The primary current was led through a wire through the hole in the disks and 10 secondary windings were wound on the rings. A current of 10 mA, 31 Hz, was used. Sintered alumina was used as electrical insu- lating material, figure 1. The assembly was placed
F G. 1. - Sample holder.
1) Copper block, 2) sintered alumina tube, 3) secondary win- dings, 4) lid, 5) sintered alumina disks, 6, 7) iron ring and alloy
ring, 8) thermocouple.
in a quartz tube inserted in an electric furnace. The measurements were performed in a vacuum of about l o p 5 mm Hg. Pure iron as well as the dilute iron alloy show just below the ferromagnetic Curie temperature a very large initial permeability associated with the vanishing magnetic anisotropy a t this temperature [7].
The transition to the paramagnetic state above the Curie temperature is very sharp. If the alloy is inhomo- geneous the peak is not as sharp. The temperature of the copper housing with sample was measured with a chromel-alumel thermocouple and recorded.
Heating at a rate of some degrees per hour, it was possible to measure the shifts accurately, figure 2.
Induction
j time
FIG. 2. - Measured permeability of one of our samples, consis-
ting of a pure iron and an iron alloy disk. The sample was heated through the Curie points at a rate of 3 OC/hour.
Apart from carbon and nitrogen the pure iron, which was from Johnson and Matthey, had an impurity content of about 10 p. p. m. The C and N was remo- ved by annealing during 24 h at 800 CC in wet hydro- gen. Almost all alloys were prepared in an argon atmosphere by a high frequency induction melting technique. If not homogeneous, the alloys were annea- led during 200 h at l 000 OC in an evacuated quartz capsule. The FeZn alloys were prepared in a n evacuated quartz capsule by means of the diffusion of zinc in iron during 2 000 h. Concentrations were determined by chemical analysis.
Depending on the element, different methods were used, some of which were specially developed by J. Kragten of this laboratory. In all cases there was agreement between the weighed in and the chemically determined concentrations.
Results. - For almost all the elements investi- gated we find a linear concentration dependence between 0.1 and 1 a t %. Only for Ge, 0 s and Ir a slight curvature was observable. In table I the change
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19711110
EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF IWPURITIES'ON THE CURIE C 1 - 331
TABLE J of the Curie temperature of iron per atomic percent solute, ATc/c, is given. More details about the way Results of the shifts of T, in iron alloys in which this table has been obtained, will be given ( A TJc) lit. on a later occasion [8]. The literature values arc also
- - - given in the table. These are in almost all cases from
Ti 3.7 OK/at % 121 3.8 oK/at % measurements for about 1 at % and more solute.
V .Cr Mn
*Co Ni Cu Zn Ga Gz.
As Mo Ru R h Pd I n Sn S b W R e 0 s Tr Pt Au
Discussion. - A discussion of the results should consider everything that is known about the electronic state of the dissolved impurity as follows from other experimental data.
At present however no theory is available with which the results obtained can be compared. A phe- nomenological description making use of the available neutron diffraction [9, 10, 111 and magnetization data has been attempted. Reasonable agreement with the observed values could be obtained. However the number of parameters to be introduced is rather Iarge as distinction should be made between elements to the right and to the left of iron in the periodic table, between transition and non transition elements and between the different transitional series [8].
Acknowledgements. - The authors would like to thank drs. N. J. W. Thijssen and Mr. A. P. L. M.
Zandee for the assistance in preparation of samples and the performance of measurements. X-ray fluo- rescence examinations of the Ga-alloys were done by Dra. B. Koch and W. Molleman a t the laboratory of Crystallography of the University of Amsterdam.
This work is part of the research program of the Foun- dation for Fundamental Research of Matter (F. 0. M.).
A1 - 1 . 6 , - 1 [I, 51 - 0.9 Note added in proof. - Recently measurements on Xi - 3.5, - 0.2 [l, 41 - 2.0 Fe with Nb and Ta were performed, the results are
Be - 1 3 [6] - 12.4 0.8 and 3.3 OK/at% respectively.
References
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(M. M.). Via STONER (E. C.), Rep. Prog. Phys., Chemie, 1930, 192, 337.
1946, 47, 11. [7] BOZORTR (R. M.), Ferromagnetism, D. van Nos- (21 ARROTT (A.) and NOAKES (J. E.), J. Appl. Phys., 1959, trand Company Inc.
30, 97 S. [8] STOELINGA (S. J. M.), Thesis University of Amster- dam, to be submitted.
"I S A w ~ ~ A ~ ~ ~ D Q ' T ~ ~ ' A , " $ P ~ ' f 5 ~ $ ~ ~ ~ ~ [9] COLLINS (M. F.) and Low (G. G.), Proc. Phys. Soc.,
1966, 37, 1344. 1965, 86, 535.
[lo] HOLDEN (T. M.), COMLY (J. B.) and Low (G. G,), 141 ARAJS (S.), Phys. Stat. Solid, 1965, 11, 121. Proc. Phys. SOC., 1967, 92, 726.
I51 PARSONS (D.), SUCKSMITH (W.) and THOMPSON (J. E.), [I1 I CAMPBELL (I. A.), PYOC. Phys. SOC., 1966, 89, 71.
Phil. Mag., 1958, 3, 1174. [12] HANSEN, Const~tution of lunary alloys, 1958.
