WC-Co cemented carbides are composites constituted for two interpenetrating networks. In this work, it is attempted by combining massive nanoindentation, statistical analysis, and implementation of a thin film model for deconvolution of the intrinsic hardness and flow stress of the metallic phase. Plotting of the experimentally data as a function of the binder mean free path results in a Hall-Petch strengthening relationship with a slope (ky) of 0.98 MPa*m1/2. This value points out the effectiveness of WC-Co phase boundaries as strong obstacles to slip propagation; and thus, for toughening of brittle phase by means of crack-bridging ductile reinforcement. Title:Hall-Petch strengthening of the constrained metallic binder in WC-Co cemented carbides: Experimental assessment by means of massive Nanoindentation and statistical analysis.Dear Professor E. J. Lavernia, Thank you for your email of July 23 informing about your positive consideration for publication of the referred manuscript, upon completion of mandatory revisions, in Materials Science and Engineering -A. From the report appended in your email, it seems that the reviewer has read the paper carefully. Please thank him for his care and criticism. As requested, we have considered the indicated comments, and our responses (and modificationsred color text in the revised version) are as follows:Reviewer#1's comments (RC): The idea of this paper is good and the paper deserves to be published in MSEA but after the addition of the mathematical equations used in treating the data. RC1.-The introduction need to be re-polished carefully from two points: a) Conversion of long statement to short one, and b) Simplify the statements.Example: There are some long statements and it is prefer to be shortened for example, in the introduction, "Within this evolution trend, although the intrinsic….for enhancing material performance", This statement need to be shortened and to be simplified.Response: We agree with this comment and the introduction has been re-polished following the comments mentioned by the reviewer as it is presented below:WC-Co cemented carbides, usually referred to as hardmetals, are established forefront materials for tools, structural components and wear parts with stringent requirements.They exhibit an exceptional combination of strength, toughness and wear resistance as a result of the extremely different properties of their two interpenetrating constitutive phases: hard, brittle carbides and a soft, ductile metallic binder. Historically, the ever increasing implementation of hardmetals has mainly taken place on the basis of replacement of steels in machining tools. Main reasons for it are the higher hardness Abstract: WC-Co cemented carbides are composites constituted for two interpenetrating networks. In this work, it is attempted by combining massive nanoindentation, statistical analysis, and implementation of a thin film model for deconvolution of the intrinsic hardness and flow stress of the metallic phase. Plotting of the experimentally data as a fun...

The current interest on the development of components on the micrometer size regime demands the evaluation of the mechanical behavior at such small length scales. Regarding cemented carbides, evaluation of mechanical properties at the micrometer scale is a relatively unexplored subject. In the present work we propose and validate a testing protocol based on uniaxial compression of micropillars milled by focused ion beam, to evaluate the elastic and plastic response of WC-Co alloys. In doing so, we studied three WC-Co alloys: fine, medium and coarse grained. First, we determined an appropriate Representative Elementary Volume (REV) to consider the tested sample as a bulk. Then, we performed uniaxial compression on the micropillars that met that REV. Based on the stiffness recorded for each micropillar, we found that the estimated elastic modulus for the fine and medium grained alloys is within the range expected for WC-Co alloys with a similar volume fraction of constitutive phases as those studied here. Finally, we stablished a correlation among stress-strain response, microstructure and yielding within constitutive phases by linking strain bursts taken place at different stress levels to plastic deformation/damage features observed in the micropillars after uniaxial compression.

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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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