Deformation behavior of Cu-composites processed by HPT

Krämer, Lisa; Wurster, Stefan; Pippan, Reinhard

doi:10.1088/1757-899x/63/1/012026

Cited by 6 publications

(8 citation statements)

References 9 publications

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“…Although the ball-milled powders have grain sizes in the range of 10-20 nm, grain growth during sintering is rapid and the densified compacts have grain diameters of several microns [3,11,13]. Complete densification remains unachievable and intergrannular porosity is still observed after sintering [3,13].High pressure torsion (HPT) has been used for grain refinement and mechanically alloying of a wide range of Cu-based systems including Cu-Fe [15][16][17], Cu-Cr [18,19], Cu-Nb [20,21] and Cu-W [22,23]. Deformation is carried out under quasi-hydrostatic conditions, allowing brittle materials such as refractory metals to be extensively strained without the need for external heating.…”

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confidence: 99%

On nanostructured molybdenum–copper composites produced by high-pressure torsion

et al. 2017

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Nanostructured molybdenum-copper composites have been produced through severe plastic deformation of liquid-metal infiltrated Cu30Mo70 and Cu50Mo50 (wt%) starting materials. Processing was carried out using highpressure torsion at room temperature with no subsequent sintering treatment, producing a porosity-free, ultrafine-grained composite. Extensive deformation of the Cu50Mo50 composite via two-step high-pressure torsion produced equiaxed nanoscale grains of Mo and Cu with a grain size of 10-15 nm. Identical treatment of Cu30Mo70 produced a ultrafine, lamellar structure, comprised of Cu and Mo layers with thicknesses of $ 5 and $ 10À20 nm, respectively, and an interlamellar spacing of 9 nm. This microstructure differs substantially from that of HPT-deformed Cu-Cr and Cu-W composites, in which the lamellar microstructure breaks down at high strains. The ultrafinegrained structure and absence of porosity resulted in composites with Vickers hardness values of 600 for Cu30Mo70 and 475 for Cu50Mo50. The ability to produce Cu30Mo70 nanocomposites with a combination of high-strength, and a fine, oriented microstructure should be of interest for thermoelectric applications.

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confidence: 99%

On nanostructured molybdenum–copper composites produced by high-pressure torsion

et al. 2017

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“…In Ref. 43, the tensile properties of pure HPT deformed bulk Cu and powder Cu are investigated. The tensile yield strength is 480 MPa for HPT-deformed bulk Cu and 630 MPa for HPT-deformed powder Cu.…”

Section: Discussionmentioning

confidence: 99%

“…The tensile yield strength is 480 MPa for HPT-deformed bulk Cu and 630 MPa for HPT-deformed powder Cu. 43 In Ref. 44, the tensile yield strengths of various nanocrystalline Cu samples (grain size ,100 nm) processed by different methods are summarized, which range between ;150 and 760 MPa.…”

Section: Discussionmentioning

confidence: 99%

High strength nanocrystalline Cu–Co alloys with high tensile ductility

Bachmaier

Rathmayr²,

Schmauch

et al. 2018

J. Mater. Res.

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A supersaturated single-phase Cu-26 at.% Co alloy was produced by high-pressure torsion deformation, leading to a nanocrystalline microstructure with a grain size smaller than 100 nm. The nonequilibrium solid solution decomposed during subsequent isothermal annealing. In situ high-energy X-ray diffraction was used to map changes linked to the separating phases, and the development of a nanoscale Cu-Co composite structure was observed. To gain further information about the relationship of the microstructure and the mechanical properties after phase separation, uniaxial tensile tests were conducted on as-deformed and isothermally annealed samples. Based on the in situ diffraction data, different isothermal annealing temperatures were chosen. Miniaturized tensile specimens with a round cross section were tested, and an image-based data evaluation method enabled the evaluation of true stress-strain curves and strain hardening behavior. The main results are as follows: all microstructural states showed high strength and ductility, which was achieved by a combination of strain-hardening and strain-rate hardening.Andrea Bachmaier received her PhD in Materials Science at the University of Leobenin 2011. For her PhD research, she followed a novel strategy to produce supersaturated solidsolutions in immiscible alloy systems by a new two-step severe plastic deformation (SPD) process to obtain bulk specimens directly. Following graduation she spent two years in industry where she led a large research project funded by the Austrian Research Promotion Agency on advanced high-strength steels. In 2013, she was awarded an Erwin-Schrödinger scholarship that allowed her to work on the mechanisms behind bulk mechanical alloying, the decomposition process of supersaturated solid solutions and its influence on the thermal stability as well as on functional and mechanical properties. She leads a research group at the Erich Schmid Institute of Materials Science in Leoben Austria. Her current research primarily focuses on the generation of metastable materials, novel nanocomposites and nanocrystalline metal-matrix composites by SPD, and ERC Starting Grant funded program on SPD processed nanoscale magnetic materials. 58

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“…% from both sides of the phase diagram were found to result in single-phase solid solutions [12]. For both alloys from the melt and powder mixtures, a continuous refinement of the Fe particles in Cu-rich alloys via fragmentation and dissolution was reported [13,14]. Also, a composite of iron fibers in a copper matrix has been deformed via HPT and the dissolution of the iron fibers was observed [15][16][17].…”

Section: Introductionmentioning

confidence: 96%

Strong and Stable Nanocomposites Prepared by High-Pressure Torsion of Cu-Coated Fe Powders

Müller

Bachmaier

Neubauer

et al. 2016

Metals

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Segregation and chemical inhomogeneity are well-known problems in powder metallurgy and are also an issue for new applications of powder mixtures, for example as starting materials for severe plastic deformation. In this study, Cu-coated Fe powder was prepared via immersion deposition, inductively hot-pressed and subsequently deformed using high-pressure torsion. The homogeneity of the pressed material was found to be much better than that of powder mixtures that were prepared for comparison. During severe plastic deformation, higher hardness was observed for the coated powder as compared to powder mixtures even after low strains. In the saturation state, the coated powder was found to result in a hardness of about 600 HV, which is significantly harder than for the powder mixtures. This is attributed to the greater amount of impurities introduced by the coating process. It is shown that coated powders are promising starting materials for severe plastic deformation in order to reduce the amount of strain necessary to reach the saturation state and to obtain high strength and more homogeneous mechanical alloying.

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Deformation behavior of Cu-composites processed by HPT

Cited by 6 publications

References 9 publications

On nanostructured molybdenum–copper composites produced by high-pressure torsion

On nanostructured molybdenum–copper composites produced by high-pressure torsion

High strength nanocrystalline Cu–Co alloys with high tensile ductility

Strong and Stable Nanocomposites Prepared by High-Pressure Torsion of Cu-Coated Fe Powders

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