COEXISTENCE OF 3 STRUCTURAL AND MAGNETIC STATES OF FE IN RAPIDLY QUENCHED SAMPLES - EPITAXY EFFECTS IN GRANULAR SOLIDS

Coexistence of three well-defined magnetic states of Fe and its correl ation with structure is analysed as a function of Fe content in FeCuNi melt spun ribbons. The granular structure of the samples enables to r eproduce in bulk state similar studies about the influence of volume e xpansion on the reinforcement of ferromagnetism in FCC Fe, to those ex tensively performed in epitaxial FCC Fe thin films. In these granular samples, the evolution of the interface area between the magnetic prec ipitates and the non-magnetic Cu rich matrix, mainly determines the ma gnetic nature of the metastable FCC Fe phases. The results show that t he equilibrium BCC Fe phase dominates the magnetic state in the sample with higher Fe content (Fe65Cu30Ni5). However, two additional metasta ble Fe phases, with expanded volume with respect to the BCC equilibriu m phase and magnetic moment per atom of 2.8 and 0.8 mu(B), are detecte d for samples with lower Fe content (Fe25Cu70Ni5 and Fe45Cu50Ni5). The evolution of both FCC metastable:Fe phases with thermal treatments is correlated with parallel changes of structure and magnetic moment obs erved in epitaxial FCC Fe thin films. The small Ni content was introdu ced to help the mixture ability of immiscible Fe and Cu. (C) 1998 Else vier Science B.V. All rights reserved.