Intrinsic hardness of constitutive phases in WC–Co composites: Nanoindentation testing, statistical analysis, WC crystal orientation effects and flow stress for the constrained metallic binder

The intrinsic hardness of the constitutive phases in WC–Co composites is investigated by combining experimental and statistical analysis nanoindentation techniques. It is done on the basis of considering the cemented carbide material as effectively heterogeneous at the microstructure scale, i.e. consisting of three phases defined by either different chemical nature (carbides and binder) or distinct carbide crystal orientation (i.e. with surface normal perpendicular to either basal or prismatic planes). As main outcome, experimentally measured and statistically significant intrinsic hardness values for the defined phases (WC and constrained metallic binder) are analyzed and determined. Besides the evidence of crystal anisotropy for the WC phase, they permit to identify and account the expected strengthening of the plastic-constrained metallic binder, a critical input parameter for hardness and toughness modelling as well as for microstructural design optimization of ceramic composites reinforced by ductile metallic ligaments.