CRYSTALLIZATION PROCESS AND MAGNETIC PROPERTIES OF Fe-RICH NANOCRYSTALS EMBEDDED ON AMORPHOUS MAGNETIC RIBBONS

Abstract

In this work we use thermal analysis methods, X-ray diffraction and magnetization measurements to carry out a systematic study on amorphous magnetic materials. In this sense, as-quenched amorphous samples of Ni 40 Fe 40 P 14 B 6 and Fe 76,5 Cu 1 Nb 3 Si 13,5 B 6 were used. We have interpreted the crystallization kinetics in terms of the Johnson/Mehl/ Avrami (JMA) nucleation-growth model. X-ray diffraction data as function of temperature reveal that our samples consist of single phases of Fe-rich nanocrystals embedded in a residual amorphous phase. Magnetic measurements as function of temperature show a sharp decreases of the magnetization around 200 and 350 0 C to Ni 40 Fe 40 P 14 B 6 and Fe 76,5 Cu 1 Nb 3 Si 13,5 B 6 , respectively, likely related to the Curie temperatures. TGA and magnetization curves show additional increases in the high temperature region which are attributed to the growth of the Fe-rich magnetic phases.