Micromechanical design to optimise materials for tools

The project includes characterising the mechanical behaviour of the two constituent phases of the hard metal: ceramic particles of WC and the cobalt-based metal binder, both of micrometric dimensions. In addition, the aim was to differentiate and understand the mechanical characteristics of the interfaces, both between WC and WC, and between the ceramic and metal phases in contact. To achieve this, one important challenge of the study is to machine microsamples of different geometries (beams and pillars) and sizes, but always under a few microns, by combining electron microscopy and focused ion beam microscopy techniques, the latter under different currents and conditions. Once the samples have been taken, their resistance to compression and fracture strength are assessed using a nanoindenter with nanometric resolution. From these tests, tensile, deformation and fracture data are obtained at microstructural scales, which are then used to optimise the microstructural design of these materials, using simulations and for the processing of new qualities of the material. These data will be used to assess different sources of errors and the reliability and reproducibility of these types of tests.

MicroMech is coordinated by the European Powder Metallurgy Association (EPMA), the technology centre CEIT and the National Physical Laboratory (United Kingdom). Other participants are the companies Hilti, Sec Tools, Ceratizit Sandvik Coromant and Kennametal. The project was completed in 2020.