Embrittlement mechanisms and magnetic properties optimization conditions in amorphous Co69Ge3.7Cr3.8Si12.5B11 alloy without ductile-brittle transition
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The influence of annealing time on the ductile-brittle transition temperature (embrittlement temperature) Т f in amorphous Co-based alloy Со69Fe3.7Cr3.8Si12.5B11 with extremely low saturation magnetostriction λ s (λ s < 10–7) is investigated. It is revealed that the embrittlement temperature Т f dependence on annealing time t a can be described by the Arrhenius equation. Embrittlement at annealing temperatures higher and lower than 300°С can be described by different kinetic parameters owing to the different states of the amorphous phase. It is shown that, in the studied alloy, the embrittlement proceeds in a very narrow annealing temperature range, not exceeding 5°С. On the basis of experimental data on the evolution of hysteresis magnetic properties during isochronous annealing and isothermal exposure, the thermal treatment mode is investigated, providing rather high values of permeability μ5 (Н = 5 mOe, f = 1 kHz) of about 50000, without transforming studied alloy into the brittle state.
Keywordsembrittlement of amorphous alloys kinetic parameters of embrittlement structural states of amorphous phase at different annealing temperatures evolution of hysteresis magnetic properties during thermal treatment
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