Issue |
J. Phys. Colloques
Volume 37, Number C6, Décembre 1976
International Conference on the Applications of the Mössbauer Effect / Conférence Internationale sur les Applications de l'Effet Mössbauer
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Page(s) | C6-769 - C6-769 | |
DOI | https://doi.org/10.1051/jphyscol:19766161 |
J. Phys. Colloques 37 (1976) C6-769-C6-769
DOI: 10.1051/jphyscol:19766161
TRANSFORMATION OF SOME AMORPHOUS FePC ALLOYS DURING ISOTHERMAL AGING
A. S. SCHAAFSMA and F. VAN DER WOUDESolid State Physics Laboratory, Materials Science Center, University of Groningen, Groningen, the Netherlands
Résumé
Des alliages amorphes Fe75P18C7 et Fe83P11C6 ont été obtenus par trempe à partir de l'état liquide (twin roller technique). Les feuilles obtenues avaient une épaisseur d'environ 25 µ et une largeur de 2 à 4 mm. Les spectres obtenus sont constitués de pics très élargis et le champ hyperfin moyen est plus important pour l'alliage le plus riche en fer. Les échantillons furent de nouveau observés après un recuit à 350 °C pendant des temps ta allant jusqu'à une semaine. Le recuit se traduit d'abord par une disparition des orientations préférentielles initiales. Puis, par la formation de clusters d'atome de fer. Le facteur À décroît d'abord très légèrement puis croît après ta = 2 000 mn. L'étude du rayon X montre la présence d'une phase cubique centrée après une semaine de recuit, le paramètre étant voisin de celui du fer métallique. Il apparaît également du Fe3P. L'influence de la pression sur la recristallisation est en cours d'étude.
Abstract
The amorphous alloys Fe75P18C7 and Fe83P11C6 have been prepared by the twin roller rapid quenching technique. The foils obtained had a thickness of about 25 µ 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 Mössbauer spectrum was recorded at room temperature. For Fe83P11C6 spectra were taken for ta = 0, 350, 850, 1 350, 1 800, 2 400 mn 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 ta = 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 Fe83P11C6 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 ta. It seems that the (mean) f-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 Fe3P). The diffraction peaks are much sharper for the iron richest alloy, indicating that the crystallites are greater in Fe83P11C6. A Mössbauer study of the amorphous-crystalline transition as a function of pressure is now in progress.