Quantitative grain structure and texture analysis of hot-pressed ZrB2 via 3D EBSD

• The grain size distribution in ZrB 2 more closely follows the gamma distribution than the lognormal distribution. • ZrB 2 grains grow into plate-like shapes, with the growth direction preferred to be orthogonal to the basal [0001] direction. • Plate-like grain morphology is more affected by crystallographic direction than the presence of a uniaxial external load (32 MPa). • Two-dimensional analysis overpredicts largest grains. • Grain shape and crystallographic-dependent growth trends are inherently 3D phenomena and cannot be adequately captured in 2D. Understanding and controlling the grain structure of ZrB 2 is critical for optimizing its mechanical and thermal performance in high-temperature applications. Fully dense ZrB 2 , densified by hot pressing at 2150˚C and 32 MPa, was analyzed in three dimensions using electron backscattered diffraction, electron and optical microscopy, and mechanical polishing serial sectioning. Grain size followed a gamma distribution, with extreme deviations observed only in the largest 0.1 % of grains. Large grains exhibited plate-like morphologies, with the shortest-to-longest axis ratio converging to ∼0.4 as grain volume increased. This work revealed a crystallographically controlled growth mechanism orthogonal to [0001] that is independent of the applied uniaxial load. Comparison with a large-area 2D scan showed that while 2D analysis captures grain size distributions, it fails to resolve correlations between grain shape and size. A synthetic hexagonal high symmetry microstructure generated with equiaxed grains and random orientations reproduced the experimental size and misorientation distributions but highlighted deviations in shape and texture observed experimentally. These findings elucidate the role of grain morphology and orientation in ZrB 2 microstructural evolution and provide guidance for designing ZrB 2 microstructures with tailored anisotropy for performance. The experimental characterization in this study offers insights into the controlled processing of ultra-high-temperature ceramics.