Investigation of structural relaxation of Fe85B15 amorphous metallic alloy by thermomagnetization

Abstract

Thermomagnelometry was used Io determine the Curie temperature of Fes~B ~ s amorphous alloy. Measurements were made with a TGS-I Perkin-Elmer thermobalance in a permanent magnetic field. Armosphous material with a thickness of ~25 lam was prepared by melt spinning.In the temperature region 300 to 800 K the sample is characterized by one Curie transformation in the amorphous matrix at Tc~570 K. A broad region of primary crystallization of ct-Fe begins at approximately 660 K, followed closely by the rapid crystallization of Fe3B phase with maximum at To,2 750 K. Amorphous material which is unstable due to quenching is relaxed by annealing, The structural relaxation causes ageing of the Curie temperature in the metallic glass.The observed phenomena might be explained in terms of certain changes in local atomic arrangement.Fe-based metallic glasses are investigated from the aspects of cheap production technology and technical application and also their interesting magnetic and mechanical properties. Metallic glasses are produced by rapid quenching (> 10 6 deg s-~) of multicomponent melts with chemical compositions close to the eutectic one. Usually, they are either highly supersaturated solid solutions or multiphase systems; they are characterized by substantial topological and chemical inhomogeneities. The specific frozen-in configuration depends on the thermal history of the sample.The annealing of glasses causes pronounced changes in the physical properties, which may be due to (a) the quenched-in internal stresses, which occur in the early stages of annealing, (b) the structural relaxation of the glassy state, or (c) the onset of crystallization or of separation into two glassy phases in the later stages of annealing.