Changes of Structure and Magnetic Properties of Fe₆₆Co₂₄Si₃B₇ Amorphous Alloy under Heat Treatment

Abstract

In this paper features of structure at the atomic level, magnetic properties, and mechanisms of structural relaxation during thermal annealing of melt-spun ribbon Fe66Co24Si3B7(ribbon thickness is 28 microns) will be discussed. By means of differential scanning calorimetry and X-ray diffraction analysis of melt-spun alloy it has been shown that structural relaxation processes have complex multi-step nature, primarily related with instability of alloy. Using this data it has been shown that magnetic structure-sensitive properties, such as coercivity and magnetic moment, can be considered as structural relaxation indicators in amorphous alloys. The original amorphous material when heated to crystallization temperature partially passes to the crystalline state, causing the increase in residual magnetic moment and coercivity.

Complex Analysis of Electrical Resistivity Dynamics of Co₈₂Fe₄Cr₃Si₈B₃ Amorphous Alloy under Heat Treatment

“…Such result indicates a non-trivial process of crystallization of the alloy, as even after crystallization it has a T c that is 5 times smaller than the one of the main alloying element. This result is significantly different from that observed by us in the alloy Fe 66 Co 24 Si 3 B 7 [1]. Evidently, this situation is the result of Cr's influence on crystallization processes in FeCo based alloys.…”

“…The alloy's structure comprises two different diffuse peaks. It should be noticed that a similar diffraction pattern was observed by us in the amorphous alloy Fe 66 Co 24 Si 3 B 7 [1]. We will not dwell on the analysis of this feature, but we should notice that it shows the complexity of initial state of the alloy.…”

“…Thus the analysis of the resistivity behavior ∆R (T) during annealing up to 560 0 C and subsequent cooling confirms that to a large degree the original structural state of the alloy preserved after annealing. It should be noted the appearance of decrease in the conductivity of the alloy associated with devitrification of amorphous phase and the beginning of complex phases of Co formation at 560 0 C. This situation is significantly different from the picture that we observed in FeCoSiB alloy [1]. 2) the ∆R(T) dependence is well approximated by quadratic functions.…”

Analysis of Structural Transformations of Fe80Ni10Si5B5 Amorphous Alloy Based on Temperature Changes of Electrical Resistivity

“…In general amorphous alloys have a much higher value of resistivity as compared to corresponding crystalline materials. As a result it's expected that upon crystallization the abrupt decrease of resistivity emerges [1]. Moreover, the magnetic nature of a material should be taken into account, which can make an additional contribution to the scattering of electrons.…”