Corelation between the crystallisation process and change in thermoelectromotive force for the amorphous alloy Fe89.8Ni1.5Si5.2B3C0.5

Abstract

Thermal and kinetic analyses of the structural changes for the amorphous alloy Fe89.8Ni1.5Si5.2B3C0.5, during the processes of non-isothermal heating and isothermal annealing, have been performed. The crystallisation process has been investigated using the method of differential scanning calorimetry (DSC). It is determined that this alloy crystalizes through three different stages. Changes in the electronic structure of the amorphous tape, for the temperature range 20 to 700ºC have been studied. This was achieved by measuring the thermoelectromotive force (TEMS), of the thermo pair made of two tapes with same chemical structure of the alloy FeNiSiBC, but different atomic structure: one is in the crystal state (CL) and the other is in the amorphous state (AM). Analysis of the temperature dependence of the electromotive force has shown the following: the investigated alloy is thermically stable up to 450ºC and changes in the atomic structure as well as equalising of the free electron density in both parts of the thermo pair AM-CL, take place in the temperature range from 450 to 550ºC. Kinetic parameters of the process were determined by measuring time dependence of the TEMS in isothermic conditions at the temperatures 450, 480 and 510ºC.

Keywords

• amorphous alloy
• crystallisation