Effect of heat treatment on phase transformations and magnetization of amorphous Co69Fe4Cr4Si12B11 microwires

The results of qualitative and quantitative changes in phase composition as well as microstructure changes of amorphous Co69Fe4Cr4Si12B11 microwires at three stage crystallization process of are presented. After first and second stages the amount of crystalline Co-phase was 36 wt%. To study magnetization of the alloy during heating, exposure and cooling a unique vibration magnetometer with a chemical microreactor was used. The unique vibration magnetometer was used for low inertia real-time measurements under controlled atmosphere. The Curie temperatures of phases formed in the crystallization process were determined. Based on the analysis of magnetization kinetic curves, nucleation and growth mechanisms were established on the stage of primary crystallization. It was found that a one-dimensional mechanism is responsible for the growth of Co-based crystals and leads to the formation of a specific needle-shaped structure. At the second crystallization stage of a metastable phase with a Co23B6 structure type was formed. The Curie temperature of this phase was 165 °C.