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Submitted on 1 Jan 1976
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TRANSFORMATION OF SOME AMORPHOUS FePC
ALLOYS DURING ISOTHERMAL AGING
A. Schaafsma, F. van der Woude
To cite this version:
JOURNAL DE PHYSIQUE Colloque
C6,
supplkmentau
no 12, Tome .-
37, Dkcembre1976,
pageC6-769
TRANSFORMATION OF SOME AMORPHOUS
-
FePC
ALLOYS DURING ISOTHERMAL AGING
A.
S. SCHAAFSMA and F. VAN DER WOUDE, Solid State Physics Laboratory, Materials Science Center,University of Groningen, Groningen, the Netherlands
Rksumk. - Des alliages amorphes Fe75P18C7 et FessP11C6 ont et6 obtenus par trempe 2 partir de 1'6tat liquide (twin roller technique). Les feuilles obtenues avaient une Bpaisseur d'environ 25 p et une largeur de 2 a 4 mm. Les spectres obtenus sont constitues de pics tres 6largis et le champ hyperfin moyen est plus important pour l'alliage le plus riche en fer. Les Bchantillons fuynt de nouveau observes apres un recuit
a
350 "C pendant des temps ta allant jusqu'h une semame. Le recuit se traduit d'abord par une disparition des orientations prefkrentielles initiales. Puis, par la formation de clusters d'atome de fer. Le facteur f decroit d'abord tres 16gerement puis croft aprhs ta = 2 000 mn.L'Btude du rayon X montre la presence d'une phase cubique centrQ apres une semaine de recuit, le parametre Btant voisin de celui du fer mktallique. I1 apparaft egalement du Fe3P.
L'influence de la pression sur la recristallisation est en cours d'ktude.
Abstract. - The amorphous alloys Fe75P18C7 and Fes3P11C6 have been prepared by the twin roller rapid quenching technique. The foils obtained had a thickness of about 25 y and a width of 2 to 4 mm. The spectra show broad peaks characteristic for such alloys. The mean magnetic splitting is the largest for the iron richest alloy.
The amorphous samples were annealed at a constant temperature of 350 "C during a time ta. After an annealing treatment the Mossbauer spectrum was recorded at room temperature.
For Fe83PllCs spectra were taken for ta = 0, 350,850, 1 350, 1 800,2 400 rnn and ta = one week. For ta = 350 mn only the relative intensities of the broad lines have changed. This may be interpreted as a decrease of initial preferred orientation. After t, = 850 mn the typical six line pattern of metallic iron appears in the spectrum indicating the formation of clusters of'iron atoms. The relative intensity of the iron six line pattern increases until ta. = 2 400 mn. After the one week anneal there Is no further change of the spectrum, which shows also other (but less intense) six line patterns which we have not tried to assign yet.
For Fe75P18C7 spectra were taken for ta = 0, 500, 1 300, 1 800 mn and ta = one week. For ta = 500 mn the pure iron six line pattern is weakly present, its intensity increasing gradually upon furhter annealing. Compared with Fe83PllCs however, the relative intensity of the iron lines is lower.
For both the alloys the total absorbed intensity changes only slightly as a function of t,. It seems that the (mean) $factor firstly decreases and after about 2 000 mn again increases upon annealing.
X-ray diffraction of the samples annealed for one week (at 350 "C) shows the presence of a bcc-phase with a lattice parameter close to that of pure iron (and also some FesP). The diffraction peaks are much sharper for the iron richest alloy, indicating that the crystallites are greater in
F ~ S ~ P I
1 ~ 6 .A Mossbauer study of the amorphous-crystalline transition as a function of pressure is now in progress.
