Reviews of topical problems

Nonequilibrium phase transformations in alloys under severe plastic deformation

  a,   a, b, §  a, b, c, *  d, e
a Mikheev Institute of Metal Physics, Ural Division of the Russian Academy of Sciences, S Kovalevskoi str. 18, Ekaterinburg, 620108, Russian Federation
b Ural Federal University named after the First President of Russia B N Yeltsin, prosp. Mira 19, Ekaterinburg, 620002, Russian Federation
c Institute of Quantum Materials Science, Konstruktorov str. 5, off 449, Yekaterinburg, 620007, Russian Federation
d Institute of Solid State Physics, Russian Academy of Sciences, Akademika Osip'yana str. 2, Chernogolovka, Moscow Region, 142432, Russian Federation
e National University of Science and Technology ‘MISIS’, Leninskii prosp. 4, Moscow, 119049, Russian Federation

Experimental results and theoretical concepts of anomalous phase transformations in alloys under severe plastic deformation (SPD) are reviewed. The unconventional phase and structural state of alloys that emerges as a result of SPD determines the unique combination of physical and chemical properties that is of interest for various applications in technology. The driving forces and possible mechanisms that implement the anomalous transformations as a function of SPD intensity, alloy composition, and temperature are discussed. We distinguish among these mechanisms two fundamental and qualitatively different ones that are due to: (i) direct 'mixing' of atoms in slip bands or (ii) accelerated diffusion on defects under locally alternating thermodynamic conditions and subsequent 'freezing' of the nonequilibrium state that is reached. Summarizing the experimental data and theoretical concepts regarding the change in microscopic transformation mechanisms as a function of temperature and/or intensity of treatment, we suggest a diagram of nonequilibrium stationary states attainable during the development of phase and structural instability under SPD. The proposed approach enables the prediction of the structural state of alloys and compounds by controlling thermodynamic and kinetic parameters of the system.

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Fulltext is also available at DOI: 10.3367/UFNe.2019.10.038671
Keywords: severe plastic deformation, mechanical alloying, disordering, amorphization, grain boundary segregation, mechanical mixing
PACS: 61.50.Ks, 62.20.F−, 64.60.Cn, 64.70.K− (all)
DOI: 10.3367/UFNe.2019.10.038671
Citation: Razumov I K, Yermakov A Y, Gornostyrev Yu N, Straumal B B "Nonequilibrium phase transformations in alloys under severe plastic deformation" Phys. Usp. 63 733–757 (2020)
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Received: 6th, May 2019, 9th, October 2019

Оригинал: Разумов И К, Ермаков А Е, Горностырев Ю Н, Страумал Б Б «Неравновесные фазовые превращения в сплавах при интенсивной пластической деформации» УФН 190 785–810 (2020); DOI: 10.3367/UFNr.2019.10.038671

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