The Σ=2 and Σ=13a grain boundary distributions in cemented tungsten carbides with/without metallic binders

作者：Li, Jingmao; Li, Xiaoqiang^*; Cao, Ting; Pan, Cunliang; Qiu, Hao; Zhang, Yuhui

来源：Materials Characterization, 2021, 173: 110872.

DOI：10.1016/j.matchar.2021.110872

• Coincidence site lattice
• Cemented carbides
• Grain boundary texture
• EBSD
• Spark plasma sintering
• Stereographic projection

Cemented tungsten carbides with/without metallic binders were prepared through spark plasma sintering (SPS). The coincidence site lattice grain boundaries of the materials were characterized by electron backscattered diffraction (EBSD) technology. Misorientation angle distribution and grain boundary plane orientation distributions of Sigma = 2 and Sigma = 13a boundaries in the above WC materials are demonstrated. The reasons for the high fraction of Sigma = 2 boundaries and the weaker misorientation texture at 30 degrees in cemented tungsten carbides without metallic binders were discussed. It was found that the binder types have little effect on the high population of Sigma = 2 boundaries in spark plasma sintered pure WC, WC-Co and WC with various ceramic binders such as Al2O3, ZrO2, Al2O3-ZrO2 and Al2O3-ZrO2-B2O3. In contrast, the mean grain size of WC carbides exhibits direct relation with the population of Sigma = 2 boundaries. The coalescence mechanism during solid-state sintering are confirmed for eliminating the 90 degrees boundaries and decreasing the intensity for habit planes distribution for Sigma = 2 boundaries. The result support the theory that the preference of Sigma = 2 low-energy boundaries in cemented carbides is rather dependent on the anisotropic surface energy of different planes than the cobalt content. This discovery facilitates to a better understanding of the origin of Sigma = 2 boundaries in WC based materials.