The β-Free Layer Formed near the Surface of Vacuum-Sintered WC–β–Co Alloys Containing Nitrogen
Year: 1981
Type: article
Abstract: A phenomenon that a layer with no β grains (named β-free layer) is formed near the specimen surface of vacuum-sintered WC–β–Co alloys containing nitrogen, was studied in detail. WC–β(N)–Co alloys (β(N): WC–TiC–TiN solid solution) with different amounts of β(N) and contents of nitrogen and carbon were mainly used as specimens.The formation of β or β(N)-free layer was found to be related to denitrification from the specimen surface during sintering. Owing to the denitrification, the nitrogen concentration in the liquid phase would decrease near the surface, resulting in an increase in the soulte concentration. Then, inward diffusion of solutes occurred with continuous dissolution of β(N) grains. The thickness of β-free layer varied as a function of sintering conditions and alloy compositions, where linear relations were always held between the thickness and the square root of sintering time. An examination on these results suggested that the thickening rate of β-free layer is being controlled by outward diffusion of nitrogen through the liquid phase in the layer.
Authors: Hisashi Suzuki, Koji Hayashi, Yasuro Taniguchi
Institution: The University of Tokyo
Language: English
Subfield: Ceramics and Composites
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1473385333