Phase transitions in Cu-based alloys under high pressure torsion

Straumal, Boris B.; Kilmametov, Askar; Korneva, Anna; Mazilkin, Andrey; Straumal, P. B.; Zięba, P.; Baretzky, B.

doi:10.1016/j.jallcom.2016.12.057

Cited by 69 publications

(47 citation statements)

References 57 publications

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“…In Figure 3 the temperature dependences of the heat flow (DSC curves) are shown for the Al-20 wt.% Zn, Al-10 wt.% Mg, and Cu-4.9 wt.% Co alloys before and after HPT-treatment. After HPT, the grain size in Al-based alloys was about 500 nm [109,113,162], and in Cu-based alloys, it was 150-300 nm [163]. Before HPT, the Al-based alloys contained the supersaturated (Al) solid solution and, respectively, the particles of Zn or Al 2 Mg 3 intermetallic phase [109,113,162].…”

Section: Resultsmentioning

confidence: 99%

“…Before HPT, the Al-based alloys contained the supersaturated (Al) solid solution and, respectively, the particles of Zn or Al 2 Mg 3 intermetallic phase [109,113,162]. The Cu-Co alloys contained supersaturated (Cu) solid solution and particles of Co [163] before HPT. After HPT, the composition of a solid solution and amount of the second phase changed slightly, but the mean effect important for this work was the grain refinement.…”

Section: Resultsmentioning

confidence: 99%

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Grain Boundary Complexions and Phase Transformations in Al- and Cu-Based Alloys

Kogtenkova

Straumal

Korneva

et al. 2018

Metals

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High-pressure torsion has been used to obtain the ultra-fine grained (UFG) state with a high specific area of grain boundaries (GBs) in Al-Zn, Al-Mg, Cu-Ag, Cu-Co, and Cu-Ni solid solutions with face-centered cubic (fcc) lattices. The UFG samples were heated in a differential scanning calorimeter (DSC). Small endothermic peaks in the DSC curves were observed in the one-phase solid-solution area of the respective phase diagrams, i.e., far away from the bulk solidus and solvus lines. A possible explanation of these endothermic peaks is based on the hypothesis of phase transformations between GB complexions. This hypothesis has been supported by observations with transmission electron microscopy and electron backscattering diffraction. The new lines of GB phase transformations have been constructed in the Al-Zn, Al-Mg, Cu-Ag, Cu-Co, and Cu-Ni bulk phase diagrams.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Grain Boundary Complexions and Phase Transformations in Al- and Cu-Based Alloys

Kogtenkova

Straumal

Korneva

et al. 2018

Metals

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“…The studies described in works [54][55][56][57] show that SPD processes not only lead to fragmentarization, particularly grain refinement, and dissolution of precipitates, but may also induce phase transformations [54]. In such case, there are questions regarding the formation [57,58] or decomposition of a supersaturated solid solution with precipitation of the second phase [59,60], as well as about the dissolution of precipitates [61,62].…”

Section: Commentarymentioning

confidence: 99%

“…In such case, there are questions regarding the formation [57,58] or decomposition of a supersaturated solid solution with precipitation of the second phase [59,60], as well as about the dissolution of precipitates [61,62]. Diffusive phase transformations need long-range mass transfer, which is ensured by the presence of crystal defects [55,56], particularly vacancies and interstitial atoms, which are intensively generated during SPD processes [40,55,63]. In this case, according to the Maxwell-Boltzmann distribution function, the diffusion coefficient D can be presented in the form of [45]:…”

Section: Commentarymentioning

confidence: 99%

Strength properties and structure of CuCrZr alloy subjected to low-temperature KOBO extrusion and heat treatment

Ostachowski

Bochniak

Łagoda

et al. 2019

Int J Adv Manuf Technol

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KOBO extrusion of metals and alloys strongly activates the point defect generation processes, as a result of which they reach a concentration exceeding the equilibrium level by many orders of magnitude. This leads to significant acceleration of diffusion phenomena which in heat-treatable alloys may cause disturbance of the thermodynamic equilibrium between the solid solution decomposition and dissolution of precipitates. In this work, measurements of mechanical and electrical properties and structural observations Cu1Cr0.1Zr alloy subjected to low-temperature KOBO extrusion at different stages of multi-variant heat treatment were conducted. In addition, the geometry of the extruded alloy's flow zone was analyzed and the obtained results made it possible to assess the effectiveness of experimental procedures, including product formation with high extrusion ratio λ, aimed at achieving of high and thermally stable functional properties of the material.

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“…A popular way to achieve ultrafine grained (UFG) or nanoscale structures (NS) is the application of severe plastic deformation (SPD) processes (such as equal channel angular pressing (ECAP) or high-pressure torsion (HPT)) that have been intensively studied during the last two decades [7]. One should note that such processes can also lead to specific strain induced structural features, such as grain boundary segregation [8], phase transitions [6,9,10] or dynamic precipitation [11,12]. Moreover, the precipitation sequence and the aging kinetics are often significantly affected in such UFG structures [11,[13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Microstructure, mechanical properties and aging behaviour of nanocrystalline copper–beryllium alloy

Lomakin

Castillo-Rodríguez

Sauvage

2019

Materials Science and Engineering: A

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A complex study of aging kinetics for both coarse-grained and nanostructured by severe plastic deformation Cu -2 wt.% Be alloy is reported. It is shown that aging of a coarse-grained alloy leads to continuous formation of nanosized CuBe body centred cubic (bcc, CsCltype) semi-coherent particles with the {220} Cu // {200} CuBe crystallographic orientation relationship. These particles created significant internal stress fields and became obstacles for dislocation glide that resulted in a change in the hardness from 95 Vickers hardness (HV) for the solubilized alloy to 400 HV for the aged one. The severe plastic deformation led to the formation of a single-phase nanograined microstructure with an average grain size of 20 nm and 390 HV. It was found that this grain size was slightly driven by grain boundary segregation. Further aging of the nanocrystalline alloy led to the discontinuous formation of precipitates on the former Cu grain boundaries and skipping of metastable phases. Significant age hardening with a maximum hardness of 466 HV for the aged nanostructured alloy was observed.Mechanical tests result revealed a strong influence of microstructure and further aging on strength capability of the alloy for both coarse-grained and nanostructured alloy. A good thermal stability in the nanostructured alloy was also noticed. Theoretical calculations of the hardness value for the CuBe phase are provided. It was shown that Be as a light alloying elements could be used for direct change of microstructure and aging behaviour of severely deformed copper alloys.

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Phase transitions in Cu-based alloys under high pressure torsion

Cited by 69 publications

References 57 publications

Grain Boundary Complexions and Phase Transformations in Al- and Cu-Based Alloys

Grain Boundary Complexions and Phase Transformations in Al- and Cu-Based Alloys

Strength properties and structure of CuCrZr alloy subjected to low-temperature KOBO extrusion and heat treatment

Microstructure, mechanical properties and aging behaviour of nanocrystalline copper–beryllium alloy

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