Formation of low-temperature deformation-induced segregations of nickel in Fe–Ni-based austenitic alloys

ABSTRACT

The authors present the results of an investigation in Fe–Ni-Cr austenitic alloys of the low-temperature deformation-induced segregations of nickel that form in the micro regions being (i) located close to grain- and subgrain boundaries and (ii) characteristic of the concentration and magnetic inhomogeneities indicated by the appearance of a dark diffraction contrast at the electron diffraction patterns taken from these regions typical (at the same time) of an enhanced value of Curie temperature. The observed effects were connected with the micro distortions caused by the local change of lattice parameter because of an increase in nickel concentration, as well as in the result of a magnetostriction dilatation. Using methods of the X-ray energy dispersive spectroscopy (XEDS) and atomic-probe body-section radiography (tomography – APT) has made it possible to determine the borders of those regions of austenite that were characteristic of an enhanced concentration of nickel in the fields of the localisation of a deformation-induced segregation of nickel in the vicinity of grain (subgrain) boundaries of austenitic alloys of the types Fe–13Cr–30Ni and Fe–37Ni–3Ti.

KEYWORDS:

• Austenitic alloy
• magnetic transformation
• deformation
• segregation of nickel
• electron microscopy
• magnetometry

Acknowledgements

Electron microscopy investigations were carried out in The Centre of Collaborative Access at M.N. Mikheev IMP UB RAS. The authors are grateful to Starikov S.A., Shabashov V.A., and Pilyugin V.P. for their help in performing the investigations.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme “Structure” No. АААА-А18-118020190116-6) and complex program of UB, RAS (project no. 18-10-2-39).