Influence of Heat Treatment and Variable Magnetic Fields on the Chemical Resistance of Amorphous Alloys Based on Iron
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INFLUENCE OF HEAT TREATMENT AND VARIABLE MAGNETIC FIELDS ON THE CHEMICAL RESISTANCE OF AMORPHOUS ALLOYS BASED ON IRON О. М. Hertsyk,1, 2 М. О. Kovbuz,1 T. H. Pereverzeva,1 А. K. Borysyuk,3 and L. M. Boichyshyn1 By the methods of chronopotentiometry, voltammetry, and scanning electron microscopy, we investigate the influence of modification of the Fe 78.5 Ni1.0 Mo 0.5Si 6.0 B14.0 and Fe 73.1Cu1.0 Nb 3.0Si15.5 B7.4 amor-
phous metallic alloys by heat treatment (373 and 473°K), holding in variable magnetic fields (50 Hz), and combined thermal and magnetic treatment of different durations on the corrosion rate of the surface of amorphous metallic alloys in a reference NaCl solution. It is shown that we can substantially increase the corrosion resistance of alloys using by applying variable magnetic fields for 3 h in the case of Fe 78.5 Ni1.0 Mo 0.5Si 6.0 B14.0 alloy and for 3 h with subsequent annealing at 473°K for 1 h in the case of Fe 73.1Cu1.0 Nb 3.0Si15.5 B7.4 alloy. Keywords: amorphous alloys based on Fe, heat treatment, variable magnetic field.
Amorphous metallic alloys (AMA) based on Fe are characterized by extremely high levels of magnetically soft properties, including extremely low coercive force and hysteresis losses, low eddy-current losses, and high magnetic permeability. This is why these materials are now used for the production of the elements of magnetic cores and units of electronic equipment. At present, the possibilities of practical application of amorphous materials are limited by their structural instability and, hence, insufficient stability of the characteristics valuable from the viewpoint of applications. This explains the development of the methods of controlled influence on the synthesis of AMA with improved parameters of temperature-and-time stability. For this purpose, it is necessary to establish the principal factors responsible for the structural stability of AMA under the actual operating conditions of magnetic elements, i.e., the complex of their functional characteristics. It is known that the addition of boron atoms and other amorphizing agents significantly enhances the stability of the amorphous phase based on Fe [1, 2]. However, the mechanism of action of the atoms of amorphizing agents is not completely clarified and requires subsequent investigations by both theoretical and experimental methods. In particularly, it is important to analyze the influence of heat treatment and variable magnetic fields on the chemical resistance of amorphous alloys. Methods of Investigation As objects of investigations, we used the samples of amorphous alloys based on Fe. These are Fe 78.5 Ni1.0 Mo 0.5Si 6.0 B14.0 and Fe 73.1Cu1.0 Nb 3.0Si15.5 B7.4 in the form of strips with a thickness of 25 µm ob-
tained by the spinning method (Institute of Metal Physics, Ukrainian National Academy of Sciences, Kyiv). Due to the method of preparation, the contact (c) and external (ex) surfaces of the AMA strips are distinguished. 1 2 3
Franko Lviv National University, Lviv, Ukraine.
Corresponding author; e-m
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