Direct influence of recovery behaviour on mechanical properties in oxygen-free copper processed using different SPD techniques: HPT and ECAP

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

doi:10.1016/j.jmrt.2017.05.005

Cited by 44 publications

(36 citation statements)

References 75 publications

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“…In these other experiments, [14][15][16][17][41][42][43] the behavior was different and instead there was evidence for a three-stage hardening behavior as fully documented in the present experiments and depicted in Figure 5. For these data, which become evident only when datum points are available at very low imposed strains, there is an intermediate stage which exists between the conventional strain hardening and the saturation stages and in this intermediate stage the hardness drops abruptly.…”

Section: Factors Affecting the Long-term Thermal Stability Of Ofhc Cusupporting

confidence: 61%

Effect of Long‐Term Storage on Microstructure and Microhardness Stability in OFHC Copper Processed by High‐Pressure Torsion

et al. 2019

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Tests are conducted to evaluate the effect of long-term storage on the microstructure and microhardness of an oxygen-free high conductivity (OFHC) copper after processing by high-pressure torsion (HPT) for various numbers of revolutions at ambient temperature. Results are presented for samples subjected to storage at room temperature through periods of either 1.25 or 7 years. The results show that an increase in storage time leads to a coarsening of the ultrafine-grained structure produced by HPT processing and a corresponding decrease in the microhardess where this is associated with the occurrence of recrystallization and grain growth. Plots of hardness against equivalent strain reveal a three-stage behavior with much lower hardness values over a range of equivalent strains of ~2-8. This behavior is similar after both storage periods but the hardness values are lower and the grain sizes are larger after II storage for the longer time. The results demonstrate that long-term storage has a significantly detrimental effect on the microstructure and hardness of ultrafine-grained OFHC Cu

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Section: Factors Affecting the Long-term Thermal Stability Of Ofhc Cusupporting

confidence: 61%

Effect of Long‐Term Storage on Microstructure and Microhardness Stability in OFHC Copper Processed by High‐Pressure Torsion

et al. 2019

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“…The microhardness saturation value of 125 HV is very close to the microhardness of oxygen-free (OF) copper deformed by HPTE under the v1w1 regime at room temperature [12], and also close to OF copper microhardness after HPT [8,15] (Table 2). The strength of the HPTE-processed copper is comparable with that of copper after ECAP, and it is not as high as that after HPT [8].…”

Section: Discussionsupporting

confidence: 52%

“…NS metals, including those processed by HPT, generally exhibit very high strength but limited tensile ductility (with a uniform elongation, only reaching a few percent) with almost no work-hardening [7]. Low ductility is believed to be an intrinsic "Achilles heel" of NS metals because the conventional deformation mechanisms cease to operate at the nanoscale level such that: (i) the dislocation slip is substantially suppressed by the extremely small grains (which, however, account for the extreme strength values in NS metals); and (ii) grain boundary (GB) sliding or diffusional creep is not active enough to accommodate plastic straining at ambient temperature [8]. However, some experimental data have hinted to the possibility that the generally observed low plasticity in NS metals might be extrinsic rather than intrinsic to these materials.…”

Section: Introductionmentioning

confidence: 99%

Structure and Tensile Strength of Pure Cu after High Pressure Torsion Extrusion

Nugmanov

Mazilkin

Hahn

et al. 2019

Metals

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The microstructure and mechanical properties of rod-shaped samples (measuring 11.8 mm in diameter and 35 mm in length) of commercially pure (CP) copper were characterized after they were processed by high pressure torsion extrusion (HPTE). During HPTE, CP copper was subjected to extremely high strains, ranging from 5.2 at central area of the sample to 22.4 at its edge. This high but varying strain across the sample section resulted in HPTE copper displaying a gradient structure, consisting of fine grains in the central area and of ultrafine grains both in the middle-radius area and at the sample edge. A detailed analysis of the tensile characteristics showed that the strength of HPTE copper with its gradient structure is similar to that of copper after severe plastic deformation (SPD) techniques, typically displaying a homogeneous structure. Detailed analysis of the contributions of various strengthening mechanisms to the overall strength of HPTE coper revealed the following: The main contribution comes from Hall–Petch strengthening due to the presence of high and low angle grain boundaries in gradient structure, which act as effective obstacles to dislocation motion. Therefore, both types of boundaries should be taken into account in the Hall–Petch equation. This study on CP copper demonstrated the potential of using the HPTE method for producing high-strength metallic materials in bulk form for industrial use.

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“…In cyclic methods of deformation, it is difficult to maintain high dislocation density in microstructure [7,46]. At large strains the development of UFG and nanocrystalline structures is accompanied by a decrease in dislocation density.…”

Section: Dislocationsmentioning

confidence: 99%

Microstructure characterization of ultrafine grained Cu alloys processed by methods with cyclic scheme of deformation

Rodak¹

2018

MATERIAL ENGINEERING

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COT (compression with oscillatory torsion) is a simple process that has the ability to deform bulk metallic samples. Performed investigations show that this method of deformation leads to grain refinement of Cu-Cr and Cu-Fe alloys. The grain size obtained via the dislocation subdivision mechanism associated with generation of non-equilibrum grain boundaries is in the UFG range. Large fraction of grain boundaries have low angles of misorientation. The limitation of the grain refinement and creation of low angles boundaries can be attributed to the extensive dynamic recovery. However, recrystallization process and deformation twinning plays a crucial role in grain refinement resulting in grain refinement to the nanoscale. The present overview shows that many structural elements accompanying formation UGF structure influence on understanding of the microstructure-properties relationship in these materials.

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Direct influence of recovery behaviour on mechanical properties in oxygen-free copper processed using different SPD techniques: HPT and ECAP

Cited by 44 publications

References 75 publications

Effect of Long‐Term Storage on Microstructure and Microhardness Stability in OFHC Copper Processed by High‐Pressure Torsion

Effect of Long‐Term Storage on Microstructure and Microhardness Stability in OFHC Copper Processed by High‐Pressure Torsion

Structure and Tensile Strength of Pure Cu after High Pressure Torsion Extrusion

Microstructure characterization of ultrafine grained Cu alloys processed by methods with cyclic scheme of deformation

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