Submicron and ultrafine grained hardmetals for microdrills and metal cutting inserts

Gille, G.; Szesny, B.; Dreyer, K.; Berg, Henk van den; Schmidt, Jürgen; Gestrich, T.; Leitner, G.

doi:10.1016/s0263-4368(01)00066-x

Cited by 228 publications

(156 citation statements)

References 9 publications

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“…[6][7][8] In this way, after being used for specific tooling in the wood and electronic industry the uses have extended to cutting tools for other materials (ferrous, non-ferrous, plastics) and industries (general machining, mining, casting, etc). 9,10 Powder size reduction to nanometric scale and development of nanostructured coatings and bulk materials are nowadays an important subject of research and have emerged as very promising materials. 10,11 In the case of cermets, nanostructured materials are considered those with a grain size smaller than 100 nm in which the high grain boundary to volume ratio enlarge the margin of improvement in their properties.…”

Section: Introductionmentioning

confidence: 99%

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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%

“…The materials obtained by HIP from nanocrystalline powders showed lower toughness, it is due to the increase in hardness by the effect of grain size, and possibly by reducing the mean free path of Co and the increase in the contiguity between carbides in the absence of liquid phase. 10 …”

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confidence: 99%

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

et al. 2011

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“…Their primary task is to preserve the particle size of starting powders in the sintered product, while at the same time influencing the properties of consolidated samples: decreasing density, increasing the value of hardness at room temperature, and also affecting toughness, hardness and creep resistance at elevated temperatures. The combination of VC-Cr 3 C 2 (TaC) proved the most effective due to its high solubility and mobility in the Co binder, which results in an optimal combination of hardness and toughness [7,8]. The process of grain growth in cemented carbides can be characterized as both continuous and discontinuous.…”

Section: Introductionmentioning

confidence: 99%

Influence of Grain Growth Inhibitors and Powder Size on the Properties of Ultrafine and Nanostructured Cemented Carbides Sintered in Hydrogen

Fabijanić

Jakovljević

Franz

et al. 2016

Metals

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Abstract:The influence of grain growth inhibitors and powder size on the microstructure and mechanical properties of ultrafine and nanostructured cemented carbides was researched. Three different WC powders, with an addition of different type and content of grain growth inhibitors GGIs, VC and Cr 3 C 2 and with d BET grain sizes in the range from 95 to 150 nm were selected as starting powders. Four different mixtures with 6 and 9 wt. % Co were prepared. The consolidated samples are characterized by different microstructural and mechanical properties with respect to the characteristics of starting powders. Increased sintering temperatures led to microstructural irregularities in the form of a discontinuous WC growth, carbide agglomerates and abnormal grain growth as a consequence of coalescence via grain boundary elimination. The addition of 0.45% Cr 3 C 2 contributed to microstructure homogeneity, reduced discontinuous and continuous grain growth, and increased Vickers hardness by approximately 70 HV and fracture toughness by approximately 0.15 MN/m 3/2 . The reduction of the starting powder to a real nanosize of 95 nm resulted in lower densities, and significant hardness increase, with a simultaneously small increase in fracture toughness. The consolidation of real nanopowders (d BET < 100 nm) solely by conventional sintering in hydrogen without isostatic pressing is not preferred.

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“…7) Hardness can be further improved by the addition of various secondary carbides such as TiC, VC, TaC or Cr 3 C 2 . [8][9][10] VC and Cr 3 C 2 are typically used in WC-Co alloys to control particle coarsening in a fine microstructure, which can be obtained by the use of ultra-fine or nano-sized raw powders. However, the addition of an excess of VC leads to the formation of a meta-stable phase of (Co 3 W 3 C) which is detrimental to overall performance.…”

Section: Introductionmentioning

confidence: 99%

Growth Inhibition of Nano WC particles in WC-Co Alloys during Liquid-Phase Sintering

Seo¹,

Kang²,

Lavernia³

2003

Mater. Trans.

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WC-10Co-xVC alloys were produced using two different sizes of WC powders (200 nm and 4.4 mm) via planetary milling and a liquidphase sintering technique. When VC was added to the WC-Co alloys, the growth of WC particles was effectively suppressed. However, this process was dependent on the amount of additive used. Since the average WC particle size became less than 1 mm, the system experienced a significant loss in carbon, resulting in the formation of an undesirable phase. The goal of this study was to determine the role of VC in controlling growth and to verify its effectiveness as a function of average WC size and inhibitor content. It was found from XRD and HREM studies that the (W,M)C phase was formed in WC-10Co-xVC-C systems. The effect of V or VC on the solubility of W in the Co matrix was also examined using HREM/EDS. The findings indicate that the presence of VC tends to reduce the solubility of W in a Co melt, thus inhibiting the dissolution and growth of WC.

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Submicron and ultrafine grained hardmetals for microdrills and metal cutting inserts

Cited by 228 publications

References 9 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

Influence of Grain Growth Inhibitors and Powder Size on the Properties of Ultrafine and Nanostructured Cemented Carbides Sintered in Hydrogen

Growth Inhibition of Nano WC particles in WC-Co Alloys during Liquid-Phase Sintering

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