The effect of chromium on the sinterability of tungsten carbide-nickel-chromium

From the viewpoint of sinterability, Cr has a tendency to inhibit grain growth. The effect of Cr additions to WC-Ni cemented carbides is that it significantly reduces the amount of solid state shrinkage. As well, increasing Cr content reduces the eutectic temperature of the binder phase. However, significant amounts of Cr are required to noticeably alter the densification of Ni bonded WC. One weight percent Cr of the overall binder content has no significant effect on densification in either the solid or liquid phases of sintering. Thus, whereas low Cr grades show a high degree of densification during solid state sintering, high Cr alloys behave in exactly the opposite manner, with most of the compact shrinkage occurring during liquid phase sintering. Even so, low Cr grades were found to densify to a greater extent than high Cr alloys under similar conditions. As well, the activation energy for compact shrinkage during solid state sintering was found to increase with increasing Cr content.