The Stability of Oxygen‐Free Copper Processed by High‐Pressure Torsion after Room Temperature Storage for 12 Months

Alawadhi, Meshal Y.; Sabbaghianrad, Shima; Huang, Yi; Langdon, Terence G.

doi:10.1002/adem.201901015

Cited by 4 publications

(5 citation statements)

References 61 publications

(115 reference statements)

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“…Higher strain amplitudes and accumulated strains also favor dislocation annihilation within the UFG structures generated during SPD. As a result, the microstructure of Cu specimens deformed under higher Δ ε will exhibit an extended free path for the moving dislocations unlocked due to changes in the strain path . This is consistent with the TEM observations in copper after MDF processing up to ε = 10.8 which revealed the existence of a denser dislocation network inside boundaries created during deformation at lower strain amplitudes.…”

Section: Discussionsupporting

confidence: 86%

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Influence of Strain Amplitude on the Microstructural Evolution and Flow Properties of Copper Processed by Multidirectional Forging

et al. 2020

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The search for the development of metals with high mechanical strength has raised intense interest in severe plastic deformation (SPD) methods. [1,2] These involve the application of intense straining to ultimately produce ultrafine-grained (UFG) materials. Among the available SPD techniques, multidirectional forging (MDF) [3-5] is one of the simplest procedures and can be readily applied in industry. During MDF processing, a cuboid workpiece is successively submitted to the same compression strain along its three orthogonal axes, so that after each three compressions (a so-called MDF cycle) the dimensions of the sample return to the unprocessed state. [4,6] MDF processing allows the determination of the material in situ stressstrain curves for every compression step and can be performed with or without the use of dies confining the plastic flow. [3,7] Although the grain refinement mechanisms associated with SPD are still not fully understood, it is generally accepted that it is caused by the fragmentation of the original grains in the material by boundaries formed from dislocation arrangements created during straining. [8] Sakai et al. [3] have emphasized the importance of the development of micro shear bands (MSBs), which are localized planar sheared regions within the initial grains, in the development of UFG structures in metals processed by different SPD procedures [3,7,9-18] This microstructural evolution is also referred to in the literature as continuous dynamic recrystallization [3,7,9,12,19] and the successive deformation at mutually orthogonal

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Section: Discussionsupporting

confidence: 86%

“…The 0.2% yield strength for a given MDF cycle was determined based on the SS curve of the first compression step in the following cycle in which the loading direction is orthogonal to the previous compression direction. A line was drawn in Figure a using an equation from a recent study fitted based on data for SPD‐processed copper …”

Section: Discussionmentioning

confidence: 99%

Influence of Strain Amplitude on the Microstructural Evolution and Flow Properties of Copper Processed by Multidirectional Forging

et al. 2020

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“…An analysis of the present data gives average hardness values across each disk of ≈594 ± 18 Hv after five turns but a slightly lower value at ≈584 ± 17 Hv after ten turns. Several investigations examined the effect of a temperature rise during HPT processing, but it was concluded that the increase in temperature is of relatively minor significance in initiating dynamic recrystallization . Accordingly, the hardness drop and the corresponding limited grain coarsening in the 5–10 turns of the HPT‐processed Mo samples are not attributed to a temperature rise but rather they are consistent with the occurrence of minor dynamic recovery at these high strain levels.…”

Section: Resultsmentioning

confidence: 97%

Microstructure and Microhardness Evolution in Pure Molybdenum Processed by High‐Pressure Torsion

Wang

Huang

et al. 2019

Adv Eng Mater

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Molybdenum, a refractory metal with a body-centered cubic lattice, is processed by high-pressure torsion (HPT) at room temperature under an applied pressure of 6.0 GPa and torsional straining from one-half to ten turns. The microstructures are characterized by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), and measurements are taken of the Vickers microhardness. The results show a gradual evolution of homogeneity in grain size and microhardness with increasing numbers of HPT turns with an average grain size of %690 nm at the sample edge after five turns and a saturation microhardness of %660 Hv. The grain size after ten turns shows a slight decrease at the center, and the microhardness is slightly lower than after five turns due to the occurrence of limited dynamic recovery.

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“…[37][38][39] Recent investigations examined the temperature rise and corresponding microstructure changes in Al, Ag, and Cu during HPT processing and it was concluded that the temperature rise is of only minor significance in initiating dynamic recrystallization. [40,41] Accordingly, the recrystallization phenomenon in Al-0.1% Mg alloy appears to be mainly due to the formation of large fractions of lattice defects from the heavy shear strains.…”

Section: Discussionmentioning

confidence: 99%

“…Several reports investigated the temperature rise due to heat generated during plastic deformation and friction inherent in the material flow during the anvil rotation through finite element modeling . Recent investigations examined the temperature rise and corresponding microstructure changes in Al, Ag, and Cu during HPT processing and it was concluded that the temperature rise is of only minor significance in initiating dynamic recrystallization . Accordingly, the recrystallization phenomenon in Al–0.1% Mg alloy appears to be mainly due to the formation of large fractions of lattice defects from the heavy shear strains.…”

Section: Discussionmentioning

confidence: 99%

An Investigation of Strain‐Softening Phenomenon in Al–0.1% Mg Alloy during High‐Pressure Torsion Processing

et al. 2020

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An Al-0.1% Mg alloy is processed by high-pressure torsion (HPT) at room temperature. The Al-0.1% Mg alloy displays strain-softening phenomenon through hardness evolution: the hardness values in the disc center area are higher than at the disc edge area after 1/2, 1, and 3 turns, and the size of the hard region in the disc center gradually reduces as the number of turns increases from 1/2 to 3 turns. The hardness values evolve toward homogeneity along the disc diameters after 5 and 10 turns. Electron backscatter diffraction (EBSD) and X-ray line profile analysis suggest that the lower hardness values at the disc edge area in the Al-0.1% Mg alloy are related to a recovery/recrystallization mechanism where the material is subjected to heavy straining.

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The Stability of Oxygen‐Free Copper Processed by High‐Pressure Torsion after Room Temperature Storage for 12 Months

Cited by 4 publications

References 61 publications

Influence of Strain Amplitude on the Microstructural Evolution and Flow Properties of Copper Processed by Multidirectional Forging

Influence of Strain Amplitude on the Microstructural Evolution and Flow Properties of Copper Processed by Multidirectional Forging

Microstructure and Microhardness Evolution in Pure Molybdenum Processed by High‐Pressure Torsion

An Investigation of Strain‐Softening Phenomenon in Al–0.1% Mg Alloy during High‐Pressure Torsion Processing

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