Influence of Thermomechanical Synthesis Conditions on Phase Composition and Magnetic Structure of Nonequilibrium Au–Co Alloys

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Abstract

The paper presents the results of study of the magnetic structure of nonequilibrium gold–cobalt alloys obtained by high pressure torsion under different thermomechanical conditions in terms of temperature and strain magnitude. X-ray diffraction data analysis by Rietveld method has revealed incomplete dissolution of cobalt after 10 anvil revolutions at 300 K. In contrast, the same shear deformation at 80 K leads to complete dissolution of cobalt, accompanied by the formation of two solid solutions with different cobalt contents. The use of magnetic force microscopy has revealed that specimens subjected to mechanosynthesis at 300 K possess the stripe domain structure that is not observed in specimens after cryo-deformation. Vibrational magnetometry of the synthesized alloys has revealed a decrease in the saturation magnetization with increasing shear strain and decreasing temperature of mechanical alloying.

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T. P. Tolmachev

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences

Author for correspondence.
Email: tolmachev@imp.uran.ru
Russian Federation, Ekaterinburg, 620108

I. A. Morozov

Institute of Continuous Media Mechanics, Ural Branch, Russian Academy of Sciences

Email: tolmachev@imp.uran.ru
Russian Federation, Perm, 614013

D. A. Shishkin

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences

Email: tolmachev@imp.uran.ru
Russian Federation, Ekaterinburg, 620108

S. A. Petrova

Institute of Metallurgy, Ural Branch, Russian Academy of Sciences

Email: tolmachev@imp.uran.ru
Russian Federation, Ekaterinburg, 620016

E. A. Tolmacheva

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences; Ural State Mining University

Email: tolmachev@imp.uran.ru
Russian Federation, Ekaterinburg, 620108; Ekaterinburg, 620114

V. P. Pilyugin

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences

Email: tolmachev@imp.uran.ru
Russian Federation, Ekaterinburg, 620108

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2. 1. MSM images of samples synthesized at 1 (a, b) and at 10 (c, d) revolutions of the anvil at room temperature (a, c) and at liquid nitrogen temperature (b, d). The internal drawings show topographic maps of the respective regions.

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3. 2. Magnetization curves for nonequilibrium Au–Co alloys synthesized at a temperature of 300 K (black) and 80 K (blue) at 1 and 10 anvil revolutions.

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