The kinetics of atomic and magnetic ordering of Co-based amorphous ribbons as affected by iron substitution

Abstract

Amorphous Co-based ribbons with general compositions Co 80− x Fe x B 10Si 10 have been prepared by the melt-spinning technique where iron has been substituted for cobalt by varying x from zero to eight At% in steps of 2At%. The kinetics of glass formation and crystallization as affected by a slight change in composition is studied by differential thermal analysis (DTA). It is observed that the thermodynamics of the metallic glass in respect of the formation of glassy state and its stability is affected by the complexity of the composition. The magnetic ordering of Co-based amorphous ribbons is measured both, by A.C. and D.C. magnetization as functions of temperature. D.C. measurements are made by using a vibrating sample magnetometer and A.C. initial permeability is measured by using a furnace in which the heating wire is wound in accordance with the bifiller technique. It is observed that, with increasing amount of iron, the glass-transition temperature ( T g) increases monotonically. The Curie temperature ( T C) and saturation magnetization ( M s) also increase with increasing iron content. The results are explained as due to higher magnetic moments of iron atoms and increased exchange interaction between iron and cobalt atoms.