An analysis of grain boundaries and grain growth in cemented tungsten carbide using orientation imaging microscopy

Tungsten carbide grains are usually prism-shaped triangular platelets in cemented tungsten carbide materials, owing to the highly anisotropic nature of tungsten carbide grains. The misorientation distribution function (MODF) shows a preferred misorientation relationship between WC/WC crystals. The misorientation relationship is characterized as 90 deg misorientation about the [1010] axis. The carbide-carbide boundaries with 90 deg rotation about the [1010] axis are low-energy boundaries and play an important role in grain growth and densification during sintering. In this study, the evolution of carbide-carbide boundaries with 90 deg rotation about the [1010] axis during the sintering process is determined quantitatively using orientation imaging microscopy (OIM). The evolution of boundaries is correlated with grain growth. The rapid grain growth at early stages of sintering is attributed to coalescence of grains along the 90 deg low-energy boundaries. The origin of these boundaries and their role in grain growth during sintering are also discussed.