Mechanisms of Cold Deformation under High Pressure of Superconductive MgB2 Ceramics
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Structures of the massive MgB2 samples deformed in Bridgman anvils that were initially in different structural states, namely, as-synthesized and post-four-stage-treated (via deformation + annealing), have been studied by methods of the X-ray diffraction, scanning and transmission electron microscopy, and measurements of microhardness. The process of the deformation of brittle ceramic samples of MgB2 under high pressure has been discussed. An analysis of the obtained data has shown that the plastic deformation of the superconductor MgB2 preliminarily compacted by a four-stage treatment has been implemented in the main through the mutual rotation of crystallites (grains) and by grain-boundary sliding without a noticeable refinement of the grain structure.
Keywords:magnesium diboride deformation annealing
The studies were performed using equipment of the Center of Collaborative Access “Test Center of Nanotechnologies and Advanced Materials,” Institute of Metal Physics, Ural Branch, Russian Academy of Sciences.The work was performed under the state task according to the theme “Pressure,” АААА-А18-118020190104-3, as well as under the project of the Ural Branch, Russian Academy of Sciences, no. 18-10-2-24.
- 1.Mechanical Behaviour of Materials under Pressure, Ed. by H. Pugh (Van Nostrand, Amsterdam, 1970; Mir, Moscow, 1973).Google Scholar
- 2.G. S. Oleinik, “Structural mechanisms of plastic deformation of ceramic materials,” in Elektron. Mikrosk. Prochn. Mater., Ser.: Fizich. Materialoved., Strukt. Svoistva Mater., No. 20, 3–30 (2014).Google Scholar
- 4.G. V. Berezhkova, P. P. Perstnev, and A. E. Romanov, “Effect of preliminary deformation at high temperature on the plastic properties of magnesium oxide crystals,” Dokl. Akad. Nauk SSSR 248, 1105–1108 (1979).Google Scholar
- 5.A. V. Leont’eva, V. A. Strel’tsov, and E. P. Fel’dman, “Brittle–plastic transition in crystals under hydrostatic pressure,” Fiz. Tekh. Vys. Davlenii, No. 22, 16–30 (1986).Google Scholar
- 6.G. S. Oleinik, V. M. Volkogon, S. K. Avramchuk, A. V. Kotko, and V. M. Vereshchaka, “The role of plastic deformation in compaction and decompaction processes upon the sintering of materials based on wurtzite modificatiopn of boron nitride,” Sverkhtverd. Mater., No. 5, 51–60 (2010).Google Scholar
- 8.R. Z. Valiev and I. V. Aleksandrov, Nanostructured Materials Obtained by Severe Plastic Deformation (Logos, Moscow, 2000) [in Russian].Google Scholar