Diffusion Behaviour of the Grain-Growth Inhibitor Vc in Hardmetals

Brieseck, M.; Hünsche, I.; Caspers, B.; Gille, G.; Bohn, Marcel; Lengauer, W.

doi:10.4028/www.scientific.net/ddf.323-325.509

Cited by 16 publications

(3 citation statements)

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“…Since GGIs are usually added as carbide powders there is a general agreement that they have to be as fine as possible in order to obtain a sufficient distribution during heat up. Previous studies [20,21] were subject to the transport of Cr and V in hardmetals during early sintering stages. The knowledge obtained in these studies can be used to estimate the distribution of GGIs during heat up in a sintering cycle.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Diffusion parameters of grain-growth inhibitors in WC based hardmetals with Co, Fe/Ni and Fe/Co/Ni binder alloys

Buchegger

Lengauer

Bernardi

et al. 2015

International Journal of Refractory Metals and Hard Materials

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Diffusion parameters of grain-growth inhibitors in WC based hardmetals with Co, Fe/Ni and Fe/Co/Ni binder alloys

Buchegger

Lengauer

Bernardi

et al. 2015

International Journal of Refractory Metals and Hard Materials

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“…Vanadium carbide is cheaper, less dense, harder and tougher than the conventional tungsten carbide, and WC-VC-Co has higher hardness for comparable toughness [8][9]. Most research on vanadium carbide is an additive to enhance wear performance, inhibit grain growth and decrease density, and it has also been used as a partial replacement for WC in WC-Co [10][11][12]. Nickel as a binder has higher resistance to thermal cracking, better oxidation resistance and wear performance in corrosive environment than cobalt [13].…”

Section: Introductionmentioning

confidence: 99%

Preliminary study of spark plasma sintered VC-Ni alloys

2018

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Vanadium carbide has outstanding tribological behaviour, superior to other similar carbides in Groups IVB and VB, except TiC. Most research on vanadium carbide uses it as an additive to enhance wear performance, inhibit grain growth and decrease density, and it has also been used as a partial replacement for WC in WC-Co. This work is on alloys of VC-Ni to provide potential lighter and more corrosion-resistant materials, and VC-Ni alloys were made by this method for the first time, and evaluated. Three alloys of compositions VC-4Ni, VC-10Ni and VC-22.1Ni (at.%) were produced by spark plasma sintering (SPS). The mixed powders were sintered at different temperatures and pressures to optimize the sintered density and hardness of the alloys. The best alloy was VC-10Ni (at.%), which had the highest density and the highest hardness.

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“…As expected, hardness and toughness follow opposite trends when increasing the amount of binder phase [7,14,49,[107][108][109][110][111][112][113] (Figure 2.16). The same happens when increasing or decreasing the WC mean grain size after sintering for a constant volume of binder content.…”

Section: Mechanical Propertiesmentioning

confidence: 54%

Sintering and mechanical properties of cemented carbides based on tungsten carbide and multicomponent metallic alloys.

Biurrun¹

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Cemented carbides are composite materials used in a wide variety of applications requiring the right combination of mechanical strength and wear resistance under harsh environments (i.e. metal cutting and shaping, civil engineering, mining, valves for the chemical industry, etc). The most common compositions comprise tungsten carbide grains bonded with a cobalt based metallic matrix. The reason is twofold. On the one hand, WC-Co materials are relatively easy to sinter to full density state with the adequate processing methodology and, on the other, a wide range of useful properties can be obtained by changing the WC grain size and the WC/Co ratio. Nevertheless, the use and availability of cobalt are presently jeopardized by both its new classification as toxic substance (REACH regulations) and the growing demand of this metal for making Li-ion batteries for electrical vehicles. The present thesis is focused on studying the sintering behavior and mechanical properties of WC-metal systems in which pure cobalt is replaced by different combinations of metals. Two promising candidates have been found: WC-NiCoCrTiAl cemented carbides These materials were designed starting from WC-NiCoCr compositions with a Ni/Co ratio equal to one. The main challenge was to increase the hardness of these compositions since it is too low compared with that of WC-Co grades. This was achieved firstly by alloying the binder phase with aluminum and, afterwards, inducing gamma prime precipitation by aging treatments. Two different aluminum containing compounds were investigated in order to avoid catastrophic oxidation of aluminum during PM processing: AlN and TiAl3. The latter produced the best results concerning sinterability and precipitation hardening effects. WC-Ni-Co-Cr-Ti-Al materials were obtained in fully dense form by using HIP after sintering technique, a process compatible with industrial processing technologies like Sinter HIP. Aging experiments show that hardness peaks occur at lower temperatures as the Al content of the binder phase increases. Apart from hardness, transverse rupture strength (TRS) was also measured in selected WC-NiCoCrTiAl compositions in both as-HIPed and solution-aged conditions. Results are only 15% lower than those reported for WC-Co materials with similar WC grain sizes and WC/metal ratios. These results also suggest that, like in as-cast Ni superalloys, the properties of the binder phase would be retained at temperatures below those used in aging treatments. WC-FeNiCoCr cemented carbides WC-Fe-Ni-Co-Cr compositions were designed following an alternative approach. In this case, the aim was to obtain a metallic binder with no precipitation of free carbon or any secondary carbide (including those of chromium). This was achieved by starting from WC-Fe-Ni-Co-Cr3C2 powder mixtures with a constant proportion between Fe, Ni and Co equal to 40/40/20. Chromium and carbon contents have been modified in order to find the upper and lower bounds defining the “so-called” carbon windows. In addition, shrinkage kinetics have been thoroughly studied in order to define a robust sintering process for both coarse and submicron WC powders. Results of calorimetric experiments have been used to improve the description of the W-C-Fe-Ni-Co quinary system for 40Fe-40Ni-20Co composition by means of ThermoCalc® software. In this case, mechanical tests confirmed that the values of hardness and transverse rupture strength are within tolerances of those reported for WC-Co grades with similar binder contents and WC grain sizes, provided that precipitation of undesired phases is avoided.

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Diffusion Behaviour of the Grain-Growth Inhibitor Vc in Hardmetals

Cited by 16 publications

References 4 publications

Diffusion parameters of grain-growth inhibitors in WC based hardmetals with Co, Fe/Ni and Fe/Co/Ni binder alloys

Diffusion parameters of grain-growth inhibitors in WC based hardmetals with Co, Fe/Ni and Fe/Co/Ni binder alloys

Preliminary study of spark plasma sintered VC-Ni alloys

Sintering and mechanical properties of cemented carbides based on tungsten carbide and multicomponent metallic alloys.

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