High pressure torsion of Cu–Ag and Cu–Sn alloys: Limits for solubility and dissolution

Straumal, Boris B.; Kilmametov, Askar; Baretzky, B.; Kogtenkova, O. A.; Straumal, P. B.; Lityńska‐Dobrzyńska, Lidia; Chulist, R.; Korneva, Anna; Zięba, P.

doi:10.1016/j.actamat.2020.05.055

Cited by 35 publications

(32 citation statements)

References 113 publications

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“…Thus, under the influence of HPT in the alloy of titanium with cobalt, the accelerated mass transfer occurs at a rate of 12-13 orders of magnitude faster than the rate of ordinary thermal diffusion at room temperature (i.e., at the HPT temperature T HPT = 30 • C). We observed earlier the similar mass transfer, accelerated by HPT, in the study of HPT-driven competition between the decomposition of a solid solution and the dissolution of precipitates in copper alloys [25].…”

Section: Discussionsupporting

confidence: 55%

“…However, it saturates after 2-3 anvil rotations together with grain size and torsion torque [20,40]. Thus, the initial instabilities during HPT evolve into the steady state [25,[41][42][43][44][45] It should be noted that decreased amount of the ω-phase after HPT was also observed in Ti-Fe alloys with 0.5, 1, 2.2 and 4wt.% Fe, if the initial state consists of mostly α -martensite in the (α/α )-phase mixture [20,28]. This happens in alloys with lower content of Fe, such as 0.5 and 1%, annealed and quenched from 950 • C. In the latter case, the amount of the ω-phase appeared to be two times lower than in Ti-4wt.%Fe alloy and could be caused by solubility of~0.04 wt.% Fe in α -martensite as well.…”

Section: Discussionmentioning

confidence: 99%

“…As was noticed above, and presented in our previous works [20,28], in addition to diffusionless (and relatively fast) α→ω transformations, the processes associated with accelerated mass transfer also occur under HPT influence. In order to describe the mass transfer driven by HPT in copper and aluminum alloys, we estimated the equivalent diffusion coefficient [25]. Now we perform similar estimations for mixing in a titanium alloy.…”

Section: Discussionmentioning

confidence: 99%

“…The Ti 2 Co intermetallic particles appear light grey. After HPT, the Ti 2 Co particles remain almost unchanged (due to their high hardness, like in Cu-based alloys [25]). Figure 1 also presents bright-field ( Figure 1c) and dark-field ( Figure 1d) TEM micrographs, together with the selected area diffraction pattern (Figure 1e) for the (α + ω) matrix of the Ti-4wt.% Co alloy after HPT preliminary annealed at 600 • C (2774 h) after HPT.…”

Section: Methodsmentioning

confidence: 99%

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Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

et al. 2020

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The development of next generation Ti-based alloys demand completely new processes and approaches. In particular, the Ti-alloys of next generation will contain not only α-Ti and β-Ti phases, but also small amounts of ω-phase and intermetallic compounds. The β→ω phase transformation induced by high-pressure torsion (HPT) has been studied in detail recently. In this work, we investigated the HPT-induced α→ω phase transformation. For this purpose, we added various β-stabilizers into α-Ti matrix of studied Ti-alloys. Ti-alloys with 4% Fe, 2% Cr, 3% Ni, and 4% Co (wt. %) have been annealed at the temperatures below their point of eutectoid decomposition, from β-Ti to α-Ti, and respective intermetallics (TiFe, Ti2Co, Ti2Ni, TiCr2). Volume fraction of HPT-driven ω-phase (from ≤5 up to ~80%) depended on the amount of alloying element dissolved in the α-matrix. Evaluation of lattice parameters revealed accelerated mass transfer during HPT at room temperature corresponding to bulk diffusion in α-Ti at ~600 °С.

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Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

et al. 2020

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“…But, for the CuSn8 alloy, the situation is more complex because of Sn solid solution that significantly affects the mobility of dislocations and also because this solid solution is metastable at room temperature [39]. During deformation, the high density of defects may promote atomic mobility and phase separation [40,41], and thus the precipitation of the Cu 3 Sn phase. X-Ray diffraction measurements were carried out (Fig.…”

Section: Figure 4: Micro-hardness As a Function Of The Shear Strain For Cu Processed By Hpt At Various Rotation Speeds (2mm Samples) And mentioning

confidence: 99%

Influence of strain rate and Sn in solid solution on the grain refinement and crystalline defect density in severely deformed Cu

Zaher

Lomakin

Enikeev

et al. 2021

Materials Today Communications

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A commercially pure Cu and a Cu-8wt.%Sn alloy were subjected to high pressure torsion (HPT) to study the effect of Sn as solute element and deformation rate on the grain refinement mechanism and the defect accumulation in Cu. The microstructure and hardness of produced ultrafine grained (UFG) states of both materials were carefully characterized. We show that addition of Sn in Cu leads to significant decrease in grain size, accumulation of higher stored energy and increase in hardness accompanied with the delay of hardness saturation with shear strain. Increasing HPT deformation rate induces significant heat dissipation in the processed materials markedly pronounced in CuSn8 as compared to Cu. Surprisingly, deformation rate has the opposite effect on the microhardness of UFG Cu and CuSn8, which decreases with the deformation rate for the case of Cu, while exhibits faster saturation to higher values for CuSn8. We also show that despite higher self-heating at higher deformation rates, higher HPT rotation speed provides reduction in grain size and increase in the defect density for CuSn8 alloy. This effect is assumed to be related to strong interactions between Sn solute atoms and strain-induced defects so that mechanically driven effects prevail over dynamic annihilation of dislocations. Finally, we present a qualitative model based on the phenomena of production and annihilation of dislocations. This model was able to reproduce the evolution of grain size, concentrations defects and hardness with different deformation parameters and after the addition of solute element in material.

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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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High pressure torsion of Cu–Ag and Cu–Sn alloys: Limits for solubility and dissolution

Cited by 35 publications

References 113 publications

Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

Influence of strain rate and Sn in solid solution on the grain refinement and crystalline defect density in severely deformed Cu

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

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High pressure torsion of Cu–Ag and Cu–Sn alloys: Limits for solubility and dissolution

Cited by 35 publications

References 113 publications

Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

Influence of strain rate and Sn in solid solution on the grain refinement and crystalline defect density in severely deformed Cu

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