Physical and chemical nature of cemented carbides

Exner, Hans Eckart

doi:10.1179/imtr.1979.24.1.149

Cited by 97 publications

(70 citation statements)

References 65 publications

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“…Carbide contiguity was deduced from best-fit equations following empirical relationships given by Roebuck and Almond [2], but extending them to include carbide size influence on the basis of extensive analysis of data from open literature [41]. Binder mean free path was finally estimated from the carbide contiguity data [1,2].The hardmetal grade under consideration exhibited a Vickers hardness of 12.8 ± 0.2 GPa. This value was averaged over five measurements made under an applied force of 294N.…”

Section: Materials and Experimental Aspectsmentioning

confidence: 99%

FIB/FESEM experimental and analytical assessment of R-curve behavior of WC–Co cemented carbides

Tarragó

Jiménez‐Piqué

Schneider

et al. 2015

Materials Science and Engineering: A

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Exceptional fracture toughness levels exhibited by WC-Co cemented carbides (hardmetals) are due mainly to toughening derived from plastic stretching of crack-bridging ductile enclaves. This takes place due to the development of a multiligament zone at the wake of cracks growing in a stable manner. As a result, hardmetals exhibit crack growth resistance (R-curve) behavior.In this work, the toughening mechanics and mechanisms of these materials are investigated by combining experimental and analytical approaches. Focused Ion Beam technique (FIB) and Field-Emission Scanning Electron Microscopy (FESEM) are implemented to obtain serial sectioning and imaging of crack-microstructure interaction in cracks arrested after stable extension under monotonic loading. The micrographs obtained provide experimental proof of the developing multiligament zone, including failure micromechanisms within individual bridging ligaments. Analytical assessment of the multiligament zone is then conducted on the basis of experimental information attained from FIB/FESEM images, and a model for the description of R-curve behavior of hardmetals is proposed. It was found that, due to the large stresses supported by the highly constrained and strongly bonded bridging ligaments, WC-Co cemented carbides exhibit quite steep but short R-curve behavior. Relevant strength and reliability attributes exhibited by hardmetals may then be rationalized on the basis of such toughening scenario.

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Section: Materials and Experimental Aspectsmentioning

confidence: 99%

FIB/FESEM experimental and analytical assessment of R-curve behavior of WC–Co cemented carbides

Tarragó

Jiménez‐Piqué

Schneider

et al. 2015

Materials Science and Engineering: A

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“…Cobalt is the most widely used binder metal in cemented carbides because the excellent interface properties exhibited by the WC-Co system [1]. However, one of the majors trends in hardmetals industry is focused in finding new binder phases to replace cobalt [2,3].…”

Section: Introductionmentioning

confidence: 99%

Fracture and fatigue behavior of WC–Co and WC–CoNi cemented carbides

Tarragó

Roa

Valle

et al. 2015

International Journal of Refractory Metals and Hard Materials

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The fracture and fatigue characteristics of several cemented carbide grades are investigated as a function of their microstructure. In doing so, the influence of binder chemical nature and content (Co and 76 wt% Co-24 wt% Ni), as well as carbide grain size on hardness, flexural strength, fracture toughness and fatigue crack growth (FCG) behavior is evaluated. Mechanical testing is combined with a detailed inspection of crack-microstructure interaction, by means of scanning electron microscopy, in order to evaluate crack-path tortuosity and to discern fracture and fatigue micromechanisms within the metallic binder. Results show that CoNi-base hardmetals exhibit slightly lower hardness but higher toughness values than Co-base grades. Meanwhile, flexural strength is found to be rather independent of the binder chemical nature. Regarding FCG behavior, experimental results indicate that: (1) FCG threshold (K th ) values for coarse-grained grades are higher than those measured for the medium-grained ones; and (2) fatigue sensitivity levels exhibited by CoNi-and Co-base cemented carbides, for a given binder mean free path, are similar. These findings are rationalized on the basis of the increasing relevance of crack deflection mechanisms as microstructure gets coarser and the evidence of similar fatigue degradation phenomena within the binder independent of its chemical nature, respectively.

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“…Young's modulus increased with the mole fraction of WC, had a maximum value of 690 GPa at 0.930 and 0.956, and then steeply decreased above 0.956. Young's modulus of WC is reported as 696 16) and 707 GPa. 17) In this study, sintered WC has a modulus value of 541 GPa.…”

Section: Microstructurementioning

confidence: 99%

Preparation of WC-WB-W<SUB>2</SUB>B Composites from B<SUB>4</SUB>C-W-WC Powders and their Mechanical Properties

Sugiyama

Taimatsu

2002

Mater. Trans.

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Sintered composites of WC-WB-W 2 B were prepared from B 4 C-W-WC powders using a reactive energization hot-pressing technique that initiated a solid state reaction between B 4 C and W. Below a WC mole fraction of 0.769 in the starting powder, WB and WC were formed according to the reaction B 4 C + 5W + xWC = WB + (1 + x)WC, while WB, W 2 B, and WC were produced above a mole fraction of 0.854. Densely sintered bodies were not obtained for pure WC. Composites of WC-WB-W 2 B obtained at WC mole fractions between 0.854 and 0.956 were fully consolidated, having high Young's modulus and Vickers hardness values, and a fracture toughness which were comparable to those of WC.

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Physical and chemical nature of cemented carbides

Cited by 97 publications

References 65 publications

FIB/FESEM experimental and analytical assessment of R-curve behavior of WC–Co cemented carbides

FIB/FESEM experimental and analytical assessment of R-curve behavior of WC–Co cemented carbides

Fracture and fatigue behavior of WC–Co and WC–CoNi cemented carbides

Preparation of WC-WB-W<SUB>2</SUB>B Composites from B<SUB>4</SUB>C-W-WC Powders and their Mechanical Properties

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