Effect of structural transformations preceding crystallization on functional properties of Fe73.5Cu1Nb3Si15.5B7 amorphous alloy

This paper investigates the effect of structural changes preceding crystallization on functional properties of ribbon-shaped Fe73.5Cu1Nb3Si15.5B7 amorphous alloy during annealing process in temperature range of 25 °C to 450 °C. It has been shown that this alloy is stable up to 500 °C when the stepwise crystallization starts. This process is preceded by structural relaxation process, including Curie temperature and the supercooled liquid region. The influence of these changes on magnetic properties of the alloy was investigated using thermomagnetic measurements, while their effect on the change in electron density of states at Fermi level was investigated by measuring thermoelectromotive force. It is also shown that magnetic susceptibility of this alloy can be increased by up to 40%, after successive annealing cycles at different temperatures. The measurements of electrical resistivity change in isothermal conditions in supercooled liquid region had been used to determine kinetic parameters of electrical conductivity. It has been shown that this process occurs in two stages: the first is kinetically controlled, whereas the second is diffusion controlled, occurring with activation energy of 139.4 J/mol K and 184.1 J/mol K, respectively.

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► Structural relaxation causes a decrease in on electron density of states at Fermi level.
► Resistivity below supercooled liquid depends mostly on electron DoS at Fermi level.
► Alloy shows increase in magnetic susceptibility on annealing below crystallization.
► Alloy shows decrease in electrical resistivity on annealing below crystallization.
► In supercooled liquid region alloy shows ionic conductivity with complex mechanism.