Some Unresolved Problems of High-Pressure Torsion

Beygelzimer, Yan; Estrin, Yuri; Kulagin, Roman

doi:10.2320/matertrans.mt-mf2022038

Cited by 5 publications

(3 citation statements)

References 124 publications

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“…In 2023, an article [41] appeared detailing the possible effects of slippage in terms of the mechanics of a deformable body, including the peculiarities of the action of frictional forces during HPT. This work confirmed our results.…”

Section: Overview Of Slippage In Hptmentioning

confidence: 99%

“…In each cycle, the material also underwent torsional deformation, which was difficult to estimate. Another point to consider is that, as mentioned above, the torsional strain/slip rate depends on the height of the sample (elevation of the sample over the groove) [41]. If we perform the cycle "cut the specimen into two halves, with the halves laid on the anvil, pressure to 6 GPa, and HPT n = 2 at the HPT stage, the height of the halves (of the specimen) was noticeably greater than the depth of the groove.…”

Section: Short Overview Of Accumulative Hptmentioning

confidence: 99%

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Slippage during High-Pressure Torsion: Accumulative High-Pressure Torsion—Overview of the Latest Results

Гундеров

Asfandiyarov

Astanin

et al. 2023

Metals

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This overview examines the results of a study of the effect of slippage in high-pressure torsion (HPT). A number of papers in this area and the works of the authors of this overview are considered. The authors used the method of the “joint HPT of the disk halves”. This method is the simplest and most illustrative method for evaluating slippage during HPT. The authors used 10 and 20 mm diameter anvils, with a groove on the lower anvil and a calculated pressure of 6 GPa. In the case of the HPT of solid bulk metal glass (BMG), slippage starts at the early stages of HPT and is total. Slippage may also be significant at the early stages of the HPT of such metallic materials as Ti, Ni, Fe-0.1%C, and Zr-2.5%Nb. Slippage increases with the number of revolutions, n. There is no slippage at the initial stages of the HPT of copper. However, after HPT Cu n = 10, slippage can be total. Nevertheless, studies show that the structure of samples using HPT, obtained by the authors, is similar to the nanostructure observed by other authors after using HPT with similar materials. Thus, notwithstanding slippage during HPT, deformation during HPT still occurs, and nanostructure formation occurs. Therefore, the formation of a nanostructure in samples during HPT is not proof of the absence of slippage. The authors provide a possible explanation for this. The authors propose a new method—“accumulative high-pressure torsion”—to achieve a high strain in various materials. In this procedure, several cycles are repeated, according to the following scheme: “HPT for n = 1 or 2 turns of the anvil → cutting the specimen into pieces → unstacking the stacked pieces on the anvil and subsequent HPT for n = 1 or 2”. Studies performed on a number of materials demonstrate that novel method transforms the structure more efficiently than regular HPT.

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Section: Overview Of Slippage In Hptmentioning

confidence: 99%

Section: Short Overview Of Accumulative Hptmentioning

confidence: 99%

Slippage during High-Pressure Torsion: Accumulative High-Pressure Torsion—Overview of the Latest Results

Гундеров

Asfandiyarov

Astanin

et al. 2023

Metals

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“…13,14) Such materials are sometimes referred to as superfunctional materials due to their superior properties. 15,16) For the most recent progress in the field of SPD, the readers are referred to a 2023 special issue of Materials Transactions, 17) which covered various aspects like processing methods, [18][19][20][21][22][23][24][25][26] structural/microstructural features, [27][28][29][30][31][32][33] mechanical/functional properties, nanostructured metallic and non-metallic materials [56][57][58][59][60][61][62][63][64][65][66][67][68] and heterostructured materials. [69][70][71][72] Among various SPD methods, ECAP and ARB have the potential for commercialization.…”

Section: Introductionmentioning

confidence: 99%

Severe Plastic Deformation of Light Metals (Magnesium, Aluminum and Titanium) and Alloys by High-Pressure Torsion: Review of Fundamentals and Mechanical/Functional Properties

Edalati

2024

Mater. Trans.

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Light metals and alloys based on magnesium, aluminum, and titanium are of significance in daily life and industrial applications due to their low density and superior mechanical and functional properties. The formation of nanostructures and ultrafine grains can further improve the properties of these materials. High-pressure torsion (HPT), as a severe plastic deformation (SPD) method, is one of the most effective processes for nanostructuring these materials. Various modifications of HPT such as conventional HPT with discs, HPT with rings, and continuous HPT with strips and wires are currently applied to light metals and their alloys, composites, intermetallics, and metallic glasses. The HPT processing of these materials is effective for grain refinement, hardening through the Hall-Petch mechanism, lattice defect generation, phase transformations, and solid-state reactions through fast diffusion with reasonable time/thermal stability. This article after discussing these fundamental issues, reviews some mechanical and functional properties of nanostructured lightweight materials such as tensile, compression, and bending properties, superplasticity including room-temperature superplasticity, wear resistance, electrical conductivity, superconductivity, biocompatibility, hydrogen production, and hydrogen storage.

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Exploring Refinement Characteristics in FeTi–Cu_x Composites: A Study of Localization and Abrasion Constraints

Schweiger,

Spieckermann,

Buchebner

et al. 2024

Adv Eng Mater

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FeTi–Cu composites with varying Cu contents are subjected to high‐pressure torsion, and their deformation behavior is explored systematically using scanning electron microscopy, microhardness, and nanoindentation. The study identifies the limiting factors influencing the refinement during severe plastic deformation. The pronounced strength differences between phases lead to fragmentation primarily through hard–hard (FeTi–FeTi) contact points, promoted by homogeneous, i.e., nonlocalized, and possibly turbulent material flow. These conditions are prevalent in Cu‐rich composites and during high‐temperature deformation. Conversely, Cu‐lean composites exhibit deformation localization, hindering the fragmentation process. Abrasion becomes an efficient refinement mechanism at the submicron‐/nanoscale, particularly for composites containing higher concentrations of nanocrystalline FeTi and exhibiting homogeneous plastic deformation. Consequently, deformation localization in Cu‐lean composites inhibits both refinement mechanisms, while Cu‐rich compositions and higher temperatures result in efficient refinement but at the risk of coarsening at the nanoscale. Refinement is localization‐limited in the former case and abrasion‐limited in the latter. Optimized processing conditions can overcome these constraints, yielding a uniform nanocomposite. This study sheds light on the intricate interplay of the mechanical properties of the respective phases in a composite, emphasizing the importance of tailored compositions and deformation conditions to optimize nanocomposites, particularly when dealing with challenging material pairings.

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Some Unresolved Problems of High-Pressure Torsion

Cited by 5 publications

References 124 publications

Slippage during High-Pressure Torsion: Accumulative High-Pressure Torsion—Overview of the Latest Results

Slippage during High-Pressure Torsion: Accumulative High-Pressure Torsion—Overview of the Latest Results

Severe Plastic Deformation of Light Metals (Magnesium, Aluminum and Titanium) and Alloys by High-Pressure Torsion: Review of Fundamentals and Mechanical/Functional Properties

Exploring Refinement Characteristics in FeTi–Cu_x Composites: A Study of Localization and Abrasion Constraints

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Some Unresolved Problems of High-Pressure Torsion

Cited by 5 publications

References 124 publications

Slippage during High-Pressure Torsion: Accumulative High-Pressure Torsion—Overview of the Latest Results

Slippage during High-Pressure Torsion: Accumulative High-Pressure Torsion—Overview of the Latest Results

Severe Plastic Deformation of Light Metals (Magnesium, Aluminum and Titanium) and Alloys by High-Pressure Torsion: Review of Fundamentals and Mechanical/Functional Properties

Exploring Refinement Characteristics in FeTi–Cux Composites: A Study of Localization and Abrasion Constraints

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Exploring Refinement Characteristics in FeTi–Cu_x Composites: A Study of Localization and Abrasion Constraints