Implementation of an effective time-saving two-stage methodology for microstructural characterization of cemented carbides

Tarragó, J.M.; Coureaux, D.; Torres, Yadir; Wu, Fu-Che; Al-Dawery, I.; Llanes, L.

doi:10.1016/j.ijrmhm.2015.10.006

Cited by 42 publications

(26 citation statements)

References 33 publications

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“…Mean carbide grain size was measured by linear intercept method using field emission scanning electron microscopy (FESEM) micrographs obtained with a JEOL-7001F unit. Carbide contiguity and binder mean free path were obtained by following the expressions proposed by Torres [20], Coureaux [21] and Tarragó et al [22] in which basic empirical relationships proposed by Roebuck and Almond [15] where modified to include carbide size influence. Before the milling, the sample surface was ground and diamond polished up to mirror-like surface finish following a 6 µm to 1 µm sequence, with a final stage of polishing with colloidal silica.…”

Section: Methodsmentioning

confidence: 99%

Scale effect in mechanical characterization of WC-Co composites

Sandoval

Rinaldi

Tarragó

et al. 2018

International Journal of Refractory Metals and Hard Materials

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© 2017 Elsevier LtdThe study of mechanical response of materials at small length scales has gained importance due to the recent advances in micro- and nano-fabrication as well as testing systems. However, most of the reported work has been dedicated to investigate single-crystals or boundary-containing metallic systems, while much less attention has been paid to composite materials, and in particular those combining soft and hard phases. In this work, a systematic procedure is followed for machining micropillars of diameters ranging from 1 to 4 µm in a WC-Co composite with a WC mean grain size around 1 µm, by means of focused ion beam milling. In-situ uniaxial compression of the micropillars and subsequent field emission scanning electron microscopy inspection were conducted. Clear size effects are evidenced. Smaller test specimens (probe size approaching the mean WC size) exhibit deformation/failure mechanisms observed for WC crystals; while for bigger sample sizes, the mechanical response involves several mechanisms directly linked with the microstructural characteristics of the bulk-like cemented carbide material. On the other hand, independent of micropillar size, carbide-carbide or carbide-binder interfaces are found to be preferential sites for nucleation of critical damage events.Peer ReviewedPostprint (author's final draft

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Section: Methodsmentioning

confidence: 99%

Scale effect in mechanical characterization of WC-Co composites

Sandoval

Rinaldi

Tarragó

et al. 2018

International Journal of Refractory Metals and Hard Materials

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“…Mean grain size was measured following the linear intercept method, using FESEM micrographs. On the other hand, carbide contiguity and binder mean free path were deduced following empirical relationships given in the literature [2,33]. A small amount of Cr 3 C 2 (i.e.…”

Section: Materials and Experimental Aspectsmentioning

confidence: 99%

Microstructural influence on tolerance to corrosion-induced damage in hardmetals

et al. 2016

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The influence of the microstructure on the tolerance of WC-Co cemented carbides to corrosion damage was studied by using residual strength as the critical design parameter. In doing so, samples were immersed in synthetic mine water solution for different times, and changes induced by corrosion exposure were assessed. A detailed 3D FIB/FESEM tomography characterization of corrosion damage-microstructure interactions is included. Results reveal that corrosion damage may result in relevant strength degradation on the basis of stress rising effects associated with the formation of surface corrosion pits. Thus, as immersion time increases strength gradually decreases. Fractographic examination reveals the formation of semi-elliptical and sharp corrosion pits for studied medium-and ultrafine-sized cemented carbides, respectively. The latter has a much more pronounced stress rising effect, and consequently higher strength losses were determined for ultrafine grades. Corrosion process consists of a selective attack of the binder that is dissolved in the corrosive media. Initially, it is located at centres of binder pools and as exposure time in the media increases, corrosion evolves consuming the rest of the pools which finally leaves an unsupported WC grain skeleton at the surface.

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“…All these results show that the volumetric fraction of each phase, as calculated after the Carbide size measurements are commonly done by the linear intercept method [17,18,[24][25][26]. This methodology may be subjected to some uncertainties due to the irregularity in the shape of the carbides grains, as the correct geometry of each grain cannot be inferred by a single cross section.…”

Section: Resultsmentioning

confidence: 99%

“…The relation of this parameter with physical properties has been intensively studied [14,16,17]. Experimental values of contiguity show a very wide dispersion [13,24] which can be explained by the influence of carbide size distribution and, in general, decreases with increasing binder content or carbide size.…”

Section: C) Contiguitymentioning

confidence: 99%

“…Although information gathered following this standard methodology has proven to be quite valuable [15][16][17][18][19][20][21][22][23][24][25][26], emphasis must be placed on the fact that real microstructure of cemented carbides is three dimensional (3D), with grains of WC being polyhedral. Hence, a 2D projection will only give partial information on the two 3D interpenetrating-phase networks characteristic for these materials.…”

Section: Introductionmentioning

confidence: 99%

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Focused ion beam tomography of WC-Co cemented carbides

Jiménez‐Piqué

Turon-Viñas

Chen

et al. 2017

International Journal of Refractory Metals and Hard Materials

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The microstructure of three different grades of WC-Co cemented carbides has been reconstructed in three dimensions after sequential images obtained by focused ion beam.The three-dimensional microstructual parameters are compared against the well-know two-dimensional parameters of grain size, phase percentages and mean free path. Results show good agreement with the exception of individual grain recognition, which could not be univocally segmented. In the case of mean free path, the three-dimensional image depicts a more realistic image of the metal interconnections in the composite.For the grade with coarser grain size, the obtained tomography is translated in a finite element modelling mesh, and elastic residual stresses are estimated from sintering to room temperature. Calculated thermal stresses agree with experimental results and show significant local variations in their value due to the complex microstructure of cemented carbides.

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Implementation of an effective time-saving two-stage methodology for microstructural characterization of cemented carbides

Cited by 42 publications

References 33 publications

Scale effect in mechanical characterization of WC-Co composites

Scale effect in mechanical characterization of WC-Co composites

Microstructural influence on tolerance to corrosion-induced damage in hardmetals

Focused ion beam tomography of WC-Co cemented carbides

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