Hypcrfinc Interactions 69 (1991) 599-602 599 HYPERFINE INTERACTIONS IN ULTRAFINE AMORPItOUS Fe--M--B (M=Ni, Co) ALLOYS M. GHAFARI', J. SAIDA', R.A. BRAND: and Y. NAKAMURA ~ tNisshin Steel, Steel R&D Laboratories, Sakai, Osaka 592, Japan 2Fachbereich Plo,Mk-Technologie, Universitiit Duisburg, Germany 3FaculO, of Science attd Technology, Ryukoku University, Otsu 520, Japan Ultraf~ne amorphous (Fe, Co, NL)-B powders have been prepared by a chemical, reduction method. The influence of the Co and Ni ai:oms on the distribution of internal magnetic fields P(B~f) has been investigated. The quadrup~]e splittlng di.sI ribulion P(QS) of ultt-afine amorphous Fe-Ni-B powders has a form .<in, i la~ to that derived for the dense random pack~ng of atoms. 1.INTRODUCTION The morphology and the boron content o[ u]traf[n~, amorphous alloys prepared by the chemical reduction of Fe-ions in an aqueous solution with KBH~ depend mainly on the mol,iY ral ic, r~f KBH{ to metal ions, M~ (Mp=MfBH4/M~et. ! : M~.~ 4, the tool concent ~.-ation of KBI{4; Mmet~]: the tool concentration (~f metal ions). To obtain more detailed information on the distribution of hyperfine flelds, we p~rformed Hossbauer effect measu;;ements for a] loys with M~:IO.0. The M6ssbauer parameters obtained fo~ rapidly quenched alloys w~re compared with those of amorphous powders. The forms of P(B~f) and P(QS), B./ and the standard deviation of magnetic hyperfine fields were studied in detail. 2. EXPER l MENTAl, U]trafine amorphous powders were prepared by adding FeSO 4 plus CoCI i or NiCl 2 solutions into a KBH 4 aqueous solution ill air. Tile molar ratio M R was chosen to be i0.0. Tlle chemical compositions of powders were determined by inductively coul,l~d pla.~;ma spectroscopy.Th~ ~ structure was examined by X- ray measurements. M6ssbauer measurements wer~ performed using a conventional constant acceleration- type spectrometer with a moving source of : Co in a Rh matrix. The isomer shift is given relative to a--Fe at room temperature. 3. RESULTS AND DISCUSSTON Tile results of 57Fe M6ssbauer spectroscopy at T=3OOK show that the iron atoms In the ternary (Fei_:{Ni., :)~ ~Bu 3 amorphous system have a non- zero magnetic moments up to about x = 0.9. Below x<0.9 ,tile Fe L~) J.C. Baltzcr A.G., Scientific Publishing Colnpany