Atomic Redistribution in a Fe-Cr System in the Course of Mechanical Alloying and Subsequent Annealing
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Evolution of the structure and atomic distribution in Fe1−xCrx (x = 0.2, 0.3, 0.4 and 0.48) samples in the course of Fe and Cr elemental powder mechanical alloying (MA), as well as during the subsequent isochronous (4 hours) annealing in the 400 °C to 700 °C temperature range, has been studied using 57Fe Mössbauer spectrometry and X-ray diffraction with a focus on the short-range order (SRO). It was established that MA proceeds in one stage for x ≤ 0.3 or three consecutive stages for x > 0.3. The single-stage process is characterized by preferential penetration of Cr into the Fe matrix, while the three-stage process comprises diffusion of Cr into Fe as in the previous case, formation of Cr- and Fe-rich areas, and formation of homogeneous α-Fe(Cr) solid solution. The change in the MA mechanism occurs as Fe is saturated with Cr and is caused by the inversion of the mixing energy sign from negative to positive. For all samples with x ≤ 0.3 annealed at all temperatures and for x > 0.3 annealed at 400 °C, only a small trend toward SRO was observed (SRO parameter < 0). The samples with x > 0.3 annealed at temperatures > 400 °C are subjected to thermally induced decomposition, which is accompanied by chromium segregations to the grain boundaries.
The work has been carried out within the framework of the Ministry of Science and Higher Education of the Russian Federation (Project No. AAAA-A17-117022250038-7) using equipment of the Shared Use Centre “Centre of Physical and Physicochemical Methods of Analysis and Study of the Properties and Surface Characteristics of Nanostructures, Materials, and Products” UdmFRC UB RAS and partially supported by the UB RAS program (Project No. 18-10-2-21).
- 1.R.L. Klueh and D.R. Harries: ASTM Stock Number: MONO3, 2001.Google Scholar
- 7.N.P. Filippova, V.A. Shabashov, A.L. Nikolaev: Phys. Met. Metallogr., 2000, vol. 90, pp. 145-152.Google Scholar
- 30.V.V. Ovchinnikov: Mössbauer Analysis of the Atomic and Magnetic Structure of Alloys. Cambridge International Science Publication Ltd., London, 2006.Google Scholar
- 34.C. Suryanarayana: Mechanical Alloying and Milling, Marcel Dekker Inc., New York, 2004, https://doi.org/10.1201/9780203020647.
- 39.G.Y. Vélez and G.A. Pérez Alcázar: J. Alloys Compd., 2015, vol. 644, pp. 1009–12. http://dx.doi.org/10.1016/j.jallcom.2015.05.004.
- 44.G.K. Wertheim: Mössbauer Effect: Principles and Application, Academic Press, New York, 1964.Google Scholar