Effect of Grain Motion on the Coarsening of WC Grains in the Carbon-Saturated Liquid Matrix During Liquid Phase Sintering of WC-Co Alloys

• Published in: Scripta materialia Vol. 38; no. 10; pp. 1563 - 1569
• Main Authors: Kim, Sona, Park, Jong-Ku, Lee, Dokyol
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Ltd 14.04.1998; Elsevier Science
• Subjects: Applied sciences; Exact sciences and technology; Foundry engineering; Melting. Treatment before casting; Metals. Metallurgy; Production techniques; Grain size; Tungsten carbide; Heat treatment; Grain growth; Liquid phase sintering; Grain boundary migration; Experimental study; Composite material; Cobalt base alloys; Sintering; Sintered material; Coalescence; Microstructure
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/S1359-6462(98)00070-0

It has been shown that the coarsening of WC grains in the WC-Co alloys is enhanced with the increase of the liquid content in the compacts under a constant carbon potential. The enhanced coarsening of WC grains in the compacts with a high cobalt content proves not to result from extrinsic effects, such as a milling effect. The surface conditions of compacts are proven to affect significantly the coarsening rate of WC grains. It is seen that the movement of liquid molecules or the liquid convection helps the WC grains to move and the grain motion accelerates a dissolution reaction since the thickness of a boundary layer around a dissolving WC grain is reduced by a self-agitation effect. The enhanced coarsening of WC grains with Co content in the WC-Co compacts is attributed to the self-agitation effect of the WC grains immersed in the liquid Co.