Abstract
The hysteresis Fe-Cr-Co alloys based on the combination of producibility and mechanical and physical properties, are promising magnetic-hard materials. The powder metallurgy provides great technological advantages for designing parts from Fe-Cr-Co system. The higher hysteresis properties were obtained due to the required morphology of α1 ordered magnetic phase. Ordering of structure made it possible to produce α1 phase at the stage of preliminary heat treatment and further development of thermal treatment. The Fe – 22,5 %Cr – 15 %Co – (4 %Mo) nanostructured powder alloys were investigated. The powders of extremely pure elements were used as their components. The use of ferrosilicon provided sintering in the presence of a liquid phase formed by contact melting, which resulting in porosity of approximately 2 %. The structure of the sintered samples had α-phase with an average grain size of 90 μm for samples without molybdenum and of 150 μm for those with molybdenum. The subsequent tempering at 520 – 550°C caused ordering of the structure, which confirmed the fragmentation of the grain to 50 μm. Preliminary ordering made it possible to increase the magnetic properties twice. The required hysteresis properties were obtained after stepwise tempering in the range of 640 – 580°С. After the treatments, the two-phase structure was formed. The lattice parameters of magnetic phases were determined. The powder hysteresis alloys developed, the technologies of their production and their treatment resulted in the superiority of the powder hysteresis alloys over widely used Vicalloys. These Fe-Cr-Co alloys are believed to be in the designing of hysteresis motor rotors.
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