Micromechanical mapping of polycrystalline cubic boron nitride composites by means of high-speed nanoindentation: Assessment of microstructural assemblage effects

Abstract

Polycrystalline cubic boron nitrides (PcBNs) are composites widely used as cutting tool materials due to their exceptional high hardness and wear resistance. Investigation of their micromechanical properties is key for optimizing PcBN’s performance through microstructural design. Within this context, high-speed nanoindentation is proposed and implemented, for three different PcBN grades, to correlate microstructure with local mechanical properties. A total of 40,000 imprints were performed in each grade. The obtained mechanical maps and data sets are statistically treated following two deconvolution approaches: 1D and 2D Gaussian fitting. The use of high-speed nanoindentation is validated not only by the reliable assessment of the intrinsic mechanical properties of cBN particles, binder and interphase region, but also by the successful mirroring of microstructural assemblage within the mechanical maps attained. Comparison of the results determined from 1D and 2D gaussian representations are in satisfactory agreement. Nevertheless, some difficulties and disparity between them arises when involving fine-grained microstructures. • Mechanical property maps replicate the microstructure assemblage of PcBN grades. • 1D and 2D representations also depict multiphase material microstructure. • Nanoindentation is validated for assessing H and E of PcBN constitutive phases. • Good agreement is generally found between 1D and 2D statistical analysis results. • Demonstration of the presence of a third composite-like/interface-related phase.