M. Miglierini et Jm. Greneche, MOSSBAUER SPECTROMETRY OF FE(CU)MB-TYPE NANOCRYSTALLINE ALLOYS .2. THE TOPOGRAPHY OF HYPERFINE INTERACTIONS IN FE(CU)ZRB ALLOYS, Journal of physics. Condensed matter, 9(10), 1997, pp. 2321-2347
Changes in the microstructure, crystallization behaviour and magnetic
state of Fe87.5-xCuxZr6.5 (x = 0,1) alloys upon annealing for one hour
at 500-840 OC are examined by Fe-57 Mossbauer spectrometry, x-ray dif
fraction and differential thermal analysis measurements. The presence
of crystallites is reflected in the Mossbauer spectra taken in the tem
perature range 77 K to 473 K as sharp lines which are superimposed on
broad features of the residual amorphous phase. The principal crystall
ine phase is identified as bcc-Fe. An early stage of crystallization i
s found even after only a 500 degrees C/1 h anneal. The total fraction
of crystalline phase increases as the temperature is increased. Hyper
fine fields of Fe atoms positioned in grain boundaries of the crystall
ites are affected by the ordered structure of the crystallites from on
e side, and by the disordered amorphous arrangement from the other. Th
e behaviour of this amorphous/crystalline interface zone is studied by
considering two independent hyperdne-field distributions. One is attr
ibuted to the interface zone and the other represents the amorphous re
mainder of the original precursor. The three-dimensional distributions
of hyperfine fields obtained from this fitting procedure, which was i
ntroduced in part I, the previous paper, enable us-after their decompo
sition into several gaussian components-to sketch a model of the topog
raphy of the hyperfine interactions within nanocrystalline samples.