Grain Refinement Kinetics in a Low Alloyed Cu–Cr–Zr Alloy Subjected to Large Strain Deformation

Morozova, A.; Bratov, Vladimir; Zherebtsov, Sergey; Belyakov, Andrey; Kaibyshev, Rustam

doi:10.3390/ma10121394

Cited by 25 publications

(25 citation statements)

References 46 publications

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“…SPD leads to the formation of unique microstructures that may contain a high dislocation density and varied proportions of low-angle boundaries (LAGBs) and high-angle boundaries (HAGBS) depending on the processing conditions [ 17 , 18 , 19 ]. Previous work has shown that SPD-processed materials may be unstable even at room temperature, and grains dynamically coarsen during creep testing at temperatures <0.3 T m [ 10 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Ultrafine-Grained Microstructure on Creep Behaviour of 9% Cr Steel

et al. 2018

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The effect of ultrafine-grained size on creep behaviour was investigated in P92 steel. Ultrafine-grained steel was prepared by one revolution of high-pressure torsion at room temperature. Creep tensile tests were performed at 873 K under the initially-applied stress range between 50 and 160 MPa. The microstructure was investigated using transmission electron microscopy and scanning electron microscopy equipped with an electron-back scatter detector. It was found that ultrafine-grained steel exhibits significantly faster minimum creep rates, and there was a decrease in the value of the stress exponent in comparison with coarse-grained P92 steel. Creep results also showed an abrupt decrease in the creep rate over time during the primary stage. The abrupt deceleration of the creep rate during the primary stage was shifted, with decreasing applied stress with longer creep times. The change in the decline of the creep rate during the primary stage was probably related to the enhanced precipitation of the Laves phase in the ultrafine-grained microstructure.

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Section: Introductionmentioning

confidence: 99%

The Effect of Ultrafine-Grained Microstructure on Creep Behaviour of 9% Cr Steel

et al. 2018

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“…The kinetics of mold flux isothermal crystallization involving nucleation and growth are analyzed through the Johnson–Mehl–Avrami (JMA) model [27,28,29,30]. According to the JMA model, the volume fraction of crystals X ( t ) is given by:

X false(t false) = 1 - \exp false(- k t^{n} false)

where X ( t ) is the relative degree of crystallinity at a given time t , including the incubation time, n is the Avrami exponent, which is associated with the nucleation and growth mechanism, and k is the effective crystallization rate constant, which is dependent on the temperature and the rate of nucleation and crystal growth.…”

Section: Resultsmentioning

confidence: 99%

Effect of Shear Stress on Isothermal Crystallization Behavior of CaO-Al2O3-SiO2-Na2O-CaF2 Slags

Wen

Ding

et al. 2018

Materials

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How to coordinate the contradiction between lubrication and heat transfer in the peritectic steel casting process is the key technical difficulty in preparing mold fluxes. The mold fluxes that are required for casting are subjected to the shear stress generated by mold oscillation and slab movement, which affects the crystallization performance of slags. The quantitative effect of slags’ crystallization performance by shear stress is studied to develop a low-basicity and high-crystallization mold flux to solve the above problem. The results show that the crystallization kinetic condition is promoted, and the crystallization activation energy is reduced by the shear stress, which leads to an increase in the crystallization temperature. Concurrently, the crystal size is reduced. However, the shear stress has no effect on the crystalline phase. The influence of different shear stresses on the crystallization ability of molten slags is related to the crystal nucleation and growth mechanisms. The crystalline fraction of the slag films at 300 rpm (69 s−1) is 44.7%, which is an increase of 17.7% compared with the crystalline fraction of the slag films at 200 rpm (46 s−1). Moreover, the shear stress has little effect on the lubricating properties of the mold fluxes, although the crystallization ability is promoted by the agitation.

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“…Благодаря легированию различными элементами (Cr, Zr, Ni, Si и др. ), в этих сплавах можно добиться существенного повышения комплекса физико-механических и эксплуатационных характеристик с помощью термомеханической обработки [1][2][3][4][5][6][7][8]. В производственных условиях, когда, как правило, используются непрерывные процессы, первым этапом обработки таких сплавов является горячая (при температурах 800 -900°С) деформация [9 -12], где основными структурообразующими процессами являются полигонизация и динамическая рекристаллизация.…”

Section: Introductionunclassified

Structural changes of the Cu-0.6Cr alloy upon cooling at different rates after a large high-temperature deformation

2020

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The present work studies changes in the structure of samples of the Cu-0.6Cr alloy in the state of a supersaturated solid solution, subjected to large plastic deformation by upsetting by 90% (e ≈ 2.0) at a temperature of 800°С and cooling in various environments: liquid nitrogen, water and air, providing different cooling rates of the material. It is shown that the cooling rate has a decisive influence on the type of structure formed. It was found that in the Cu-0.6Cr alloy, a decrease in the cooling rate leads to a decrease in the fraction of high-angle boundaries and to the formation of a finer structure at the meso and micro levels. At the same time, strength and conductivity values grow. At a high cooling rate (liquid nitrogen), the structural state corresponding to the stage of dynamic recrystallization and polygonization is observed. Such a structure has a low dislocation density and more perfect boundaries. When cooling in air at the first stage, post-dynamic recrystallization processes develop, associated with the nucleation of new nuclei of recrystallized grains along the boundaries of deformed grains, as well as the development of a substructure. The average grain and subgrain size decreases to 1.7± 0.2 and 1.1± 0.2 μm, respectively. With further cooling, from a temperature of ≈600°С, two competing processes that develop during aging obviously begin to occur, namely, the recovery of the structure and the decomposition of the solid solution. This is evidenced from a decrease in the lattice parameter and an increase in electrical conductivity (up to 79% IACS), and the close interaction of dispersed particles 5-10 nm in size and dislocations leads to the further development of the substructure. At the same time, the proportion of middle-angle boundaries increases and the proportion of twin boundaries decreases, while the proportion of high-angle boundaries of the general type remains practically unchanged.

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Grain Refinement Kinetics in a Low Alloyed Cu–Cr–Zr Alloy Subjected to Large Strain Deformation

Cited by 25 publications

References 46 publications

The Effect of Ultrafine-Grained Microstructure on Creep Behaviour of 9% Cr Steel

The Effect of Ultrafine-Grained Microstructure on Creep Behaviour of 9% Cr Steel

Effect of Shear Stress on Isothermal Crystallization Behavior of CaO-Al2O3-SiO2-Na2O-CaF2 Slags

Structural changes of the Cu-0.6Cr alloy upon cooling at different rates after a large high-temperature deformation

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