Abstract
The experimental studies of Fe68Ni32 and Fe23Ni77 alloys by transmission electron microscopy and X-ray electron spectroscopy show that the ordering-separation phase transition in these alloys occurs in a temperature range near 600°C. At temperatures higher than the transition temperature, the ordering energy of the alloy is positive, and the structures contain clusters enriched in one of the components. After heat treatment at the temperatures where the invar effect in the Fe68Ni32 alloy is maximal, a modulated microstructure forms. Below the transition temperature, the ordering energy is negative, which provides a tendency to formation of chemical compounds. After aging at these temperatures (where the Fe23Ni77 alloy exhibits high permalloy properties), highly dispersed completely coherent particles of the FeNi3 phase with structure L12 precipitate in a solid solution.
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Original Russian Text © Yu.I. Ustinovshchikov, I.N. Shabanova, N.V. Lomova, 2015, published in Metally, 2015, No. 3, pp. 60–66.
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Ustinovshchikov, Y.I., Shabanova, I.N. & Lomova, N.V. Microstructures responsible for the invar and permalloy effects in Fe-Ni alloys. Russ. Metall. 2015, 389–394 (2015). https://doi.org/10.1134/S0036029515050158
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DOI: https://doi.org/10.1134/S0036029515050158