The influence of composition, phase transformation and varying the relative F.C.C. and H.C.P. phase contents on the properties of dilute CoWC alloys

Roebuck, B; Almond, E. A.; Cottenden, A

doi:10.1016/0025-5416(84)90179-4

Cited by 120 publications

(72 citation statements)

References 12 publications

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“…Assessment of D* from equation (2) requires reliable inputs for yield strength of unconstrained binder ligaments (σ 0 ) and critical crack tip stress intensity factor required for crack initiation (K t ). A value of 600 MPa may be taken for σ 0 , from the reference work by Roebuck and Almond [48]. This value of strength is significantly higher than that expected for bulk Co, as expected from the solid solution strengthening contribution associated with dissolved tungsten and carbon [48,49].…”

Section: Analytical Assessment Of R-curve Behavior: Toughening Mechanicsmentioning

confidence: 96%

“…A value of 600 MPa may be taken for σ 0 , from the reference work by Roebuck and Almond [48]. This value of strength is significantly higher than that expected for bulk Co, as expected from the solid solution strengthening contribution associated with dissolved tungsten and carbon [48,49]. It may be assumed that the K t value is equal to the corresponding fatigue crack growth threshold (for a load ratio of 0.1), which in its turn is linearly dependent on the grain size [50] due to the action of crack-deflection as an additional toughening mechanism in cemented carbides [27,50].…”

Section: Analytical Assessment Of R-curve Behavior: Toughening Mechanicsmentioning

confidence: 99%

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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: Analytical Assessment Of R-curve Behavior: Toughening Mechanicsmentioning

confidence: 96%

Section: Analytical Assessment Of R-curve Behavior: Toughening Mechanicsmentioning

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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“…Since the binder phase is the most vulnerable component of a sintered hardmetal, much effort has been devoted to studying the interdiffusion processes that occur between the carbides and the binder phase [7][8][9][10] and their influence on the corrosion resistance of the binder phase and the hardmetals in aggressive media [7,[11][12][13]. Corrosion of hardmetals in neutral and acidic media usually leads to a preferential dissolution of the binder phase leaving a skeleton of carbides [6,14,15].…”

Section: Introductionmentioning

confidence: 99%

Influence of binder metal and surface treatment on the corrosion resistance of (W,Ti)C-based hardmetals

Barbatti

Sket

García³

et al. 2006

Surface and Coatings Technology

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The effect of a nitridation surface treatment on the microstructure and corrosion resistance of Co and Ni-binder (W,Ti)C-based hardmetals with additions of (Ta,Nb)C was investigated. Nitridation treatment produces a surface layer with a higher hard phase (Ti,Ta,Nb,W)(C,N) content. The near-surface layer thickness and microstructure are affected by the choice of binder (Co respectively Ni). The corrosion resistance of the hardmetals was characterized using linear sweep voltammetry. The microstructure of the hardmetals was determined before and after corrosive attack by optical microscopy and SEM. The results of the corrosion tests and microstructure analyses are interpreted in terms of the correlation between the hardmetal morphology and porosity and ion transport through the interface binder-electrolyte. The nitridation treatment of the hardmetals strongly increases the resistance to aggressive corrosion media for hardmetals both with Co and Ni-binder phase and thus may positively influence the hardmetal lifetime in cutting applications in chemically aggressive environments.

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“…), but above a temperature of 700 K this structure modifies to face centered cubic (f.c.c.). Roebuck et al 9 found by examining diffraction patterns obtained from electron microscopy, that the binder was predominantly f.c.c. in sintered WC-Co alloys.…”

Section: Binder Metalsmentioning

confidence: 99%

Erosion-corrosion resistance of tungsten carbide hard metals with different binder compositions

Wentzel¹

1995

Wear

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A study has been made of the slurry erosion resistance of a series of cemented tungsten carbides with different binder compositions consisting of combinations of cobalt, nickel and chromium. Testing was carried out on a specially designed laboratory rig in both tap and salt water using silica sand as an erodent.The synergistic action of erosion and corrosion on WC hard metals results in greatly enhanced wear rates compared to either erosion or corrosion processes alone.Cemented carbides with a 1 0 wt% binder were found to have a better slurry erosion resistance than the corresponding 6 wt% binder grades or the pure metal binder alloys alone. The performance of all the materials was found to be much worse in a salt water medium compared to tap water.The alloying of either pure Nickel or Cobalt binders was found to influence the fracture properties and corrosion resistance and lead to an improvement in the slurry erosion resistance of the cemented carbides. However any improvement in the corrosion resistance of the binder did not directly enhance the slurry erosion resistance of the cermet. Explanations are advanced to explain these differences in behaviour linked to chemical composition, mechanical properties of the binder phase and the dynamic nature of the slurry erosion system.Comparisons are also made between the performance of the Ni-Cr-Co based cermets and the pure alloyed metal binder grades. The acceptability of modelling the slurry erosion and corrosion resistance of cermets based on the behaviour of the binder phase materials is discussed. CONTENTS

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The influence of composition, phase transformation and varying the relative F.C.C. and H.C.P. phase contents on the properties of dilute CoWC alloys

Cited by 120 publications

References 12 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

Influence of binder metal and surface treatment on the corrosion resistance of (W,Ti)C-based hardmetals

Erosion-corrosion resistance of tungsten carbide hard metals with different binder compositions

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