Behavior of temperature dependence of permeability curves at different stages of crystallizations of nanocrystalline Fe70.5Cr3Cu1Nb3Si13.5B9

Nanocrystalline amorphous ribbons of composition Fe70.5 Cr3 Cu1Nb3 Si 13.5 B9 prepared by rapid solidification technique have been studied in the present work. Amorphicity of the ribbons has been confirmed by X-ray diffraction. Crystallization temperatures were identified by X-ray diffraction and crystallization products were analyzed by XRD. When annealed below the crystallization temperature, i.e. when the sample is in amorphous state, temperature dependence of permeability curves were characterized by sharp increase of permeability and subsequent fall to lower value near ferro-paramagnetic transition temperature, which is typical Hopkinson effect for soft ferromagnetic single phase material. Under devitrification, when the sample is in a two phase state, the sharpness of the descent to lower values of permeability is smeared out. This smearing effect is caused by distribution of the Curie temperature of the Fe-depleted residual amorphous matrix. During heating and cooling, it has been observed from a graph of μ (T) that the value of permeability and TC at cooling had increased slightly faster than the heating due to relaxation of the sample. Above the crystallization temperature, we noticed that the heating and cooling curve of μ (T) are almost superimposed.