Microstructural and mechanical characterisation of WC–Co alloys elaborated by liquid phase sintering and hot isostatic pressing: study of WC crystallites size evolution

Rabouhi, Hassiba; Eyidi, D.; Khelfaoui, Youcef; Khireddine, Abdelkrim

doi:10.1080/00084433.2022.2066240

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…The changes in the shape of WC grains were also observed through the preparation of conventional WC-Co cemented carbides using laser powder bed fusion [ 16 ], hot isostatic pressing [ 17 ] and spark plasma sintering [ 18 ], as well as through varying the carbon [ 19 ] and cobalt content [ 20 ].…”

Section: Modification Of Fabrication Parameters Of Conventional Wc-co...mentioning

confidence: 99%

Faceting/Roughening of WC/Binder Interfaces in Cemented Carbides: A Review

Straumal

Konyashin

2023

Materials

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Hardmetals (or cemented carbides) were invented a hundred years ago and became one of the most important materials in engineering. The unique conjunction of fracture toughness, abrasion resistance and hardness makes WC-Co cemented carbides irreplaceable for numerous applications. As a rule, the WC crystallites in the sintered WC-Co hardmetals are perfectly faceted and possess a truncated trigonal prism shape. However, the so-called faceting–roughening phase transition can force the flat (faceted) surfaces or interfaces to become curved. In this review, we analyze how different factors can influence the (faceted) shape of WC crystallites in the cemented carbides. Among these factors are the modification of fabrication parameters of usual WC-Co cemented carbides; alloying of conventional cobalt binder using various metals; alloying of cobalt binder using nitrides, borides, carbides, silicides, oxides; and substitution of cobalt with other binders, including high entropy alloys (HEAs). The faceting–roughening phase transition of WC/binder interfaces and its influence on the properties of cemented carbides is also discussed. In particular, the increase in the hardness and fracture toughness of cemented carbides correlates with transition of WC crystallites from a faceted to a rounded shape.

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Section: Modification Of Fabrication Parameters Of Conventional Wc-co...mentioning

confidence: 99%

Faceting/Roughening of WC/Binder Interfaces in Cemented Carbides: A Review

Straumal

Konyashin

2023

Materials

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“…The lengths of the semiaxes of such ellipses, which characterize the dimensions of the continuous regions of the cobalt binder, were also determined. However, in some cases, the edges and corners of WC grains become rounded such as in the WC-12 wt.% Co cemented carbides manufactured using the selective electron beam melting (SEBM) [36,37], laser powder bed fusion [38], hot isostatic pressing [39], spark plasma sintering [40], as well as by varying the carbon [41] and cobalt content [42]. The alloying of conventional cobalt binders with various metals such as Al, Ni and W can change the equilibrium shape of WC crystals.…”

Section: Introductionmentioning

confidence: 99%

Topology of WC/Co Interfaces in Cemented Carbides

et al. 2023

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WC–Co cemented carbides build one of the important classes of metal matrix composites. We show in this paper that the use of machine vision methods makes it possible to obtain sufficiently informative statistical data on the topology of the interfaces between tungsten carbide grains (WC) and a cobalt matrix (Co). For the first time, the outlines of the regions of the cobalt binder were chosen as a tool for describing the structure of cemented carbides. Numerical processing of micrographs of cross sections of three WC–Co alloys, which differ in the average grain size, was carried out. The distribution density of the angles in the contours of cobalt “lakes” is bimodal. The peaks close to 110° (so-called outcoming angles) correspond to the contacts between the cobalt binder and the WC/WC grain boundaries. The peaks close to 240° (or incoming angles) correspond to the WC “capes” contacting the cobalt “lakes” and are determined by the angles between facets of WC crystallites. The distribution density of the linear dimensions of the regions of the cobalt binder, approximated with ellipses, were also obtained. The distribution density exponentially decreases with the lengths of the semi-axes of the ellipsoid, approximating the area of the cobalt binder. The possible connection between the obtained data on the shape of cobalt areas and the crack trajectories in cemented carbides is discussed.

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“…It is reported that HIP can improve the properties of tungsten alloy [ 13 , 14 , 15 ]. Rabouhi et al [ 16 ] studied the microstructural and mechanical characterization of tungsten alloys fabricated by liquid phase sintering and HIP. They found an obvious improvement in mechanical properties by using HIP compared to liquid phase sintering.…”

Section: Introductionmentioning

confidence: 99%

Effect of Hot Isostatic Pressing Process Parameters on Properties and Fracture Behavior of Tungsten Alloy Powders and Sintered Bars

Cai

2022

Materials

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In order to investigate the effect of hot isostatic pressing (HIP) process parameters on the properties and fracture behavior of tungsten alloy, HIP experiments with different process parameters were carried out, and the relative density, Rockwell hardness, tensile properties, and tensile fracture behavior were analyzed. The results show that after HIP, the tungsten alloy samples obtained further densification, higher relative density and hardness, and lower dispersity. At 1300 °C and 140 MPa, the sintered bar achieved excellent mechanical properties: yield strength increased by 16.5%, tensile strength increased by 16.1%, and fracture strength increased by 85.3%. Comparing the two processes, the mechanical properties of tungsten alloy powders formed directly via HIP were not as good as those of the sintered bars. In addition, after HIP, the fracture mode of the tungsten alloy sintered bar samples was mainly ductile tear, and that of the tungsten alloy powder samples was mainly a full brittle fracture.

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Microstructural and mechanical characterisation of WC–Co alloys elaborated by liquid phase sintering and hot isostatic pressing: study of WC crystallites size evolution

Cited by 4 publications

References 10 publications

Faceting/Roughening of WC/Binder Interfaces in Cemented Carbides: A Review

Faceting/Roughening of WC/Binder Interfaces in Cemented Carbides: A Review

Topology of WC/Co Interfaces in Cemented Carbides

Effect of Hot Isostatic Pressing Process Parameters on Properties and Fracture Behavior of Tungsten Alloy Powders and Sintered Bars

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