2001 Volume 48 Issue 1 Pages 51-60
We have developed an economical new fabrication process of WC-Co base cemented carbides with highly oriented plate-like triangular prismatic WC grains by using special W+C mixed powder instead of conventional WC powder, and already reported that the new alloy has superior room-temperature mechanical properties, compared with the conventional alloy.
In this study, the mechanism of such WC grain formation was investigated in detail. It was clarified that the formation has its origin in both the flattening of W granular particles to plate-like shape by ball-milling and their highly unidirectional orientation by die-pressing, and is assisted by both the formation of highly unidirectional plate-like Co-W-C compounds (CoxWyCz) particles and its change to highly unidirectional plate-like triangular prismatic WC grains during solid state heating. Such formation of WC grains is attributed to both the higher nucleation and/or growth rate of WC grains having (0001) crystal plane parallel to the geometrical basal plane of plate-like CoxWyCz particles. Furthermore, the formation is also assisted by non-collapse of such WC grains configuration during the appearance and solidification of Co-W-C liquid phase.
