Influence Of The Mean Carbide Size On The Micromechanical Response Of WC-Co Hardmetals

Mechanical response and properties of WC-Co composites, at macro-scale, are influenced by its microstructural characteristics such as mean carbide grain size and binder mean free path. However, information at micro-scale is rather scarce. The following study gives insights into the mechanical response at micrometric length scale of WC-Co. To this purpose, micropillars of 2 µm in diameter milled in two WC-Co grades, with different WC mean grain sizes (around 1 and 2 µm), were uniaxially compressed. Results revealed small-scale plasticity events at around 2.5 and 1.8 GPa for the medium and coarse grades respectively, bringing insights into the constraint degree of the metallic Co binder. On the other hand, differences on stress levels for evidencing large-scale yielding (4.5 GPa for medium grade and 2 GPa for coarse one) are speculated to result from plastic deformation within the constitutive phases, i.e. WC particles and less-constrained binder (close to the interface), respectively.