FIB/FESEM experimental and analytical assessment of R-curve behavior of WC-Co cemented carbides
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. A...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2015 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/82266 |
| Acceso en línea: | https://hdl.handle.net/2117/82266 https://dx.doi.org/10.1016/j.msea.2015.07.090 |
| Access Level: | acceso abierto |
| Palabra clave: | Tungsten carbide-colbalt alloys A. micromechanics FIB/FESEM R-curve B. Cemented carbides D. Fracture Toughness fracture-toughness evaluation crack-growth-resistance ductile-phase toughening mechanisms residual strength brittle materials silicon-nitride deformation composites hardmetals Carburs Aliatges de carbur de tungstè i cobalt -- Propietats mecàniques Metalls Àrees temàtiques de la UPC::Enginyeria dels materials |
| Sumario: | 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. (C) 2015 Elsevier B.V. All rights reserved. |
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