Tailoring hardness and toughness in WC–13%Co–x TiC–y TiN (x = 5, 7.5–y = 5, 7.5) functional gradient hardmetals (FGHMs)

WC–Co hardmetals continue to gain importance for cutting, milling, lathing, and mining and as chip-less forming tools, as well as for high-performance construction and wear parts. With growing demands on the performance of cutting tools and the ongoing development of more and more sophisticated coating systems, nowadays a lot of effort is put into optimizing the surface microstructure of sintered parts. One development in this field was functional gradient hardmetals, where it was possible to avoid the problems of the interface between coating and substrate. In the present study, inverse functional gradient hardmetals (FGHMs) with combination of WC–13%Co–x TiC–y TiN (x = 5, 7.5–y = 5, 7.5) were produced by powder metallurgy method under controlled atmosphere furnace. This article describes the development of functionally graded hardmetals prepared in situ by sintering in reactive atmosphere. The microstructures of the FGHMs were examined by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). Mechanical properties of the samples were examined by micro-hardness, Vicker's hardness and cutting tests.

► Size and value of TiC are effective on mechanical properties of the inverse FGHMs.
► Maximum hardness and lifetime in the sample with 15% nano fcc-phase
► Maximum density and minimum roughness in the sample with 15% nano fcc-phase
► Maximum toughness in the sample containing 10% micro fcc-phase