Structural Mechanism of Reverse α → γ Transformation and New Functional Properties of Fe-Ni Austenitic Alloys

Abstract:

The structure of the metastable austenite Fe–32%Ni alloy quenched for martensite and subjected to the α→γ transformation at slow heating (to 593–773 K) with the formation of a nanocrystalline austenite of different orientation was investigated. Electron diffraction analysis has revealed that nickel-enriched nanocrystalline γ-phase obtain ordered L10 superstructure. Together with the γ-phase, there was detected the disperse ε-martensite with a hexagonal close-packed (hcp) lattice. Along with the realization of ordinary orientation relationships (ORs) of Kurdjumov-Sachs, between a matrix α-phase and an ordered γ-phase in the sample of Fe-32%Ni alloy after slow heating to 773 K there have been established Headley-Brooks Ors. Cyclic transformation promotes the improvement of many functional properties of steels (strength, coercive force, controlling of the thermal expansion coefficient and others).

• Periodical: Materials Science Forum (Volumes 738-739)
• Pages: 200-205
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.738-739.200
• Online since: January 2013
• Authors: V.V. Sagaradze, I.G. Kabanova, N.V. Kataeva, M.F. Klyukina
• Keywords: Cyclic Martensitic Transformation γ→ε,α→γ, Fe-Ni Austenitic Alloys, Magnetic Property, Nanocrystalline γ Phase, Ni Redistribution, Ordering, Strengthening, Thermal Expansion Coefficient

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