Uncovering the liquid phase sintering mechanism of binderless cemented carbides

Binderless cemented carbides exhibit superior hardness and excellent resistance to high temperature, abrasion as well as corrosion and shows a great application prospect in optical component molds and water-jet nozzles. Metal carbides are usually introduced into the binderless tungsten carbide system to form a solid solution and facilitate the full densification of a green body. Understanding the intrinsic sintering mechanism behind such a solid solution effect has broad technological implications. In this study, transmission Kikuchi diffraction, com-plemented by aberration-corrected electron microscopy was employed to investigate the structure and chemistry of all the constitutional phases and interfaces. The (TixCryWz)C solid solution is found to establish an epitaxial crystallization habit on the basal planes of a majority of cemented carbide grains as well as the surfaces of partially dissolved TiC particles. The prevailing existence of coherent interfaces suggests the operation of a liquid phase sintering mechanism. This is also substantiated by the existence of anisotropic interfacial premelting films with chemistry resembling that of the (TixCryWz)C solid solution. The proposed liquid phase sintering mechanism offers theoretical guidelines for sintering densified binderless systems.