Influence of the grain size and structural state of grain boundaries on the parameter of low-temperature and high-rate superplasticity of nanocrystalline and microcrystalline alloys

Чувильдеев, В. Н.; Щавлева, А. В.; Нохрин, А. В.; Пирожникова, О. Э.; Gryaznov, M. Yu.; Lopatin, Yu. G.; Sysoev, A. N.; Мелехин, Н. В.; Сахаров, Н. В.; Копылов, В. И.; Myshlyaev, М. M.

doi:10.1134/s1063783410050422

Cited by 14 publications

(4 citation statements)

References 13 publications

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“…The third factor contributing to higher superplastic characteristics of UFG alloys is the nonequilibrium state of their high-angle grain boundaries. As shown in [99,[110][111][112][113], during ECAP, HAGBs accumulate dislocation defects, leading to an increase in the free volume of grain boundaries and a decrease in the activation energy of superplastic deformation. During superplastic deformation of UFG alloys, their grain boundaries actively interact with lattice dislocations, thus triggering an increase in the free (excess) volume of high-angle grain boundaries [99,[111][112][113].…”

Section: Discussionmentioning

confidence: 99%

“…As shown in [99,[110][111][112][113], during ECAP, HAGBs accumulate dislocation defects, leading to an increase in the free volume of grain boundaries and a decrease in the activation energy of superplastic deformation. During superplastic deformation of UFG alloys, their grain boundaries actively interact with lattice dislocations, thus triggering an increase in the free (excess) volume of high-angle grain boundaries [99,[111][112][113]. Thus, ECAP provides all the necessary conditions conducive to the superplasticity effect in aluminum alloys.…”

Section: Discussionmentioning

confidence: 99%

“…It is usually assumed that  * = b, Deff = D0exp(Qeff/kT), where Qeff is effective activation energy of superplastic flow. Qeff is usually close to grain boundary diffusion activation energy Qb [109], but in the case of UFG metals, it often turns out to be less than Qb [99,111,112], and in the case of multiphase materials or in the case of diffusion creep, it can be greater than Qb [101].…”

Section: Discussionmentioning

confidence: 99%

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Effect of Sc, Hf, and Yb Additions on Superplasticity of a Fine-grained Al-0.4%Zr Alloy

Нохрин¹,

Gryaznov²,

Shotin³

et al. 2022

Preprint

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The research was undertaken to study the way deformation behaves in ultrafine-grained (UFG) conducting Al-Zr alloys doped with Sc, Hf, and Yb. All in all, 8 alloys were studied with zirconium partially replaced by Sc, Hf, and/or Yb. Doping elements (X = Zr, Sc, Hf, Yb) in the alloys total 0.4 wt.%. The choice of doping elements is conditioned by possible precipitation of Al3X particles with L12 structure while annealing these alloys. Such particles provide higher thermal stability of a nonequilibrium UFG microstructure. Initial coarse-grained samples were obtained by induction casting. The UFG microstructure in the alloys was formed by Equal Channel Angular Pressing (ECAP) at 225°C. Superplasticity tests were carried out at temperatures ranging from 300 to 500 °C and strain rates varying between 3.310-4 and 3.310-1 s-1. The highest values of elongation to failure are observed in Sc-doped alloys. A UFG Al-0.2%Zr-0.1%Sc-0.1%Hf alloy has maximum ductility: at 450 °C and a strain rate of 3.310-3 s-1, relative elongation to failure reaches 765%. At the onset of superplasticity, stress–strain curves are characterized by a stage of homogeneous strain and a long stage of localized plastic flow. The dependence of homogeneous strain (eq) on test temperature in UFG Sc-doped alloys is increasing uniformly, which is not the case for other UFG alloys with eq(T) dependence peaking at 350-400 оС. Strain rate sensitivity coefficient of flow stress m is small and does not exceed 0.26-0.3 at 400-500 °C. In UFG alloys containing no scandium, m coefficient is observed to go down to 0.12-0.18 at 500 оС. It has been suggested that lower m values are driven by intensive grain growth and pore formation in large Al3X particles, which develop specifically at the ingot crystallization stage.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Effect of Sc, Hf, and Yb Additions on Superplasticity of a Fine-grained Al-0.4%Zr Alloy

Нохрин¹,

Gryaznov²,

Shotin³

et al. 2022

Preprint

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show abstract

“…This is because UFG materials are found to have a unique combination of high strength and ductility [2][3][4], corrosion resistance [5] and radiation resistance [6], high-rate superplasticity [2,[7][8][9], etc.…”

Section: Introductionmentioning

confidence: 99%

The use of Spark Plasma Sintering method for high-rate diffusion welding of high-strength UFG titanium alloys

Нохрин

Чувильдеев

Болдин

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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The Use of SPS for High-Rate Diffusion Welding of High-Strength Ultrafine-Grained α-Titanium Alloy Ti-5Al-2V

Нохрин

Болдин

Пискунов

et al. 2019

Spark Plasma Sintering of Materials

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Influence of the grain size and structural state of grain boundaries on the parameter of low-temperature and high-rate superplasticity of nanocrystalline and microcrystalline alloys

Cited by 14 publications

References 13 publications

Effect of Sc, Hf, and Yb Additions on Superplasticity of a Fine-grained Al-0.4%Zr Alloy

Effect of Sc, Hf, and Yb Additions on Superplasticity of a Fine-grained Al-0.4%Zr Alloy

The use of Spark Plasma Sintering method for high-rate diffusion welding of high-strength UFG titanium alloys

The Use of SPS for High-Rate Diffusion Welding of High-Strength Ultrafine-Grained α-Titanium Alloy Ti-5Al-2V

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