Consolidation of advanced WC–Co powders

Parasiris, A.; Hartwig, K. T.

doi:10.1016/s0263-4368(00)00005-6

Cited by 32 publications

(16 citation statements)

References 16 publications

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“…2,3 In general, reducing WC grain size improves mechanical properties, increasing hardness, wear behaviour and transverse rupture strength without compromising toughness. 4,5 Traditionally WC-Co cermets have been produced by sintering of micrometric powders (1-4 mm). Looking for higher mechanical properties and the needed of smaller and higher precision tooling has led to the use of finer powders, being classified as submicrometric (,0?6 mm) and ultrafine (,0?3 mm) which have showed their excellent potential of improvement.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of ultrafine and nanocrystalline WC–Co mixtures by planetary milling and subsequent consolidations

et al. 2011

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In this work ultrafine and nanocrystalline WC-Co mixtures were obtained by low energy milling in planetary ball mill. The effect of the processing conditions on the reduction and distribution of the grain sizes and the internal strains level were studied. The characterisation of the powder mixtures was performed by means of scanning and transmission electron microscopy and X-ray diffraction analysis. Observations through SEM and TEM images showed a particle size below 100 nm, after milling. The X-ray diffraction profile analysis revealed a WC phase refined to a crystallite size of 19 nm. The mixtures obtained have been consolidated and mechanical and microstructurally characterised. The results show improvements in resistant behaviour of the material consolidated from nanocrystalline powders, in spite of the grain growth experienced during the sintering. The best results were found for the material obtained by wet milling during 100 h, which presents values of hardness higher than 1800 HV.

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Section: Introductionmentioning

confidence: 99%

Fabrication of ultrafine and nanocrystalline WC–Co mixtures by planetary milling and subsequent consolidations

et al. 2011

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“…WC-Co cermets with a grain size of less than 1.0 μm sintered by conventional methods were reported [1][2][3][4][5]. However, because of complex sintering procedures, the conventional sintering method showed disadvantages in several respects, especially, it is impossible to prepare cermets with a WC grain size of less than 100 nm by this method.…”

Section: Introductionmentioning

confidence: 99%

Preparation of ultrafine WC-Co cermets by combining pretreatment and consolidation with spark plasma sintering

et al. 2009

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Ultrafine-grained WC-Co bulk materials were prepared by a new method that contains pretreatment of the milled powder mixture and subsequent spark plasma sintering (SPS). Ball milling parameters and the pretreatment temperature have significant effects on the microstructure and properties of WC-Co cermets. The prepared cermets have a mean grain size of less than 0.5 μm even with a pretreatment temperature as high as 1300°C. The WC-10wt.%Co cermet bulk prepared by the optimized milling, pretreatment, and SPS processing achieves excellent mechanical properties with a Vickers hardness of HV 1643, a fracture toughness of 13.1 MPa⋅m 1/2 and a transverse rapture strength of 3100 MPa.

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“…The ECAE process also permits a variety of deformation configurations by changing the orientation of the billet with respect to the extrusion axis after each pass. For details on the nomenclature used in ECAE processing, refer to References 8,41,42,44,and 45. The overall objectives of this study were to (1) consolidate micro-and nanometer-sized copper particles without significant grain growth by optimizing extrusion routes, (2) keep track of microstructural evolution during different extrusion routes, (3) obtain very high strength and reasonable ductility levels in NC copper, (4) compare the resulting mechanical behavior of consolidated micro-and nanopowders with each other and with severely deformed ECAE-processed coarse-grained copper, and (5) shed some light onto the governing deformation mechanisms through observed microstructural evolutions and variations in mechanical properties. It was expected that the comparison of properties of copper samples with grain sizes from the micron range down to the nanometer range (Ͻ100 nm), fabricated using the same processing technique, would minimize the effects of using different processing methods and, thus, help understand the governing deformation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolution and mechanical behavior of bulk copper obtained by consolidation of micro- and nanopowders using equal-channel angular extrusion

Haouaoui

Караман

Harwig

et al. 2004

Metall Mater Trans A

112

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The consolidation of copper micro-and nanoparticles (325 mesh, 130 nm, and 100 nm) was performed using room-temperature equal-channel angular extrusion (ECAE). The effects of extrusion route, number of passes, and extrusion rate on consolidation performance were evaluated. The evolution of the microstructure and the mechanical behavior of the consolidates were investigated and related to the processing route. Possible deformation mechanisms are proposed and compared to those in ECAEprocessed bulk Cu. A combined high ultimate tensile stress (470 MPa) and ductility (ϳ20 pct tensile fracture strain) with near-elasto-plastic behavior was observed in consolidated 325-mesh Cu powder. On the other hand, early plastic instability took place, leading to a continuous softening in flow stress of bulk ECAE-processed copper. Increases in both strength and ductility were evident with an increasing number of passes in the bulk samples, which appears to be inconsistent with grain-boundarymoderated deformation mechanisms for a microstructure with an average grain size of 300 to 500 nm. Instead, this increase is attributed to microstructural refinement and to dynamic recovery and bimodal grain-size distribution. Near-perfect elastoplasticity in consolidated 325-mesh Cu powder is explained by a combined effect of strain hardening accommodated by large grains in the bimodal structure and softening caused by recovery mechanisms. Compressive strengths as high as 760 MPa were achieved in consolidated 130-nm copper powder. Although premature failure occurred during tensile loading in 130-nm consolidated powder, the fracture strength was still about 730 MPa. The present study shows that ECAE consolidation of nanoparticles opens a new possibility for the study of mechanical behavior of bulk nanocrystalline (NC) materials, as well as offering a new class of bulk materials for practical engineering applications.

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Consolidation of advanced WC–Co powders

Cited by 32 publications

References 16 publications

Fabrication of ultrafine and nanocrystalline WC–Co mixtures by planetary milling and subsequent consolidations

Fabrication of ultrafine and nanocrystalline WC–Co mixtures by planetary milling and subsequent consolidations

Preparation of ultrafine WC-Co cermets by combining pretreatment and consolidation with spark plasma sintering

Microstructure evolution and mechanical behavior of bulk copper obtained by consolidation of micro- and nanopowders using equal-channel angular extrusion

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