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Hexagonal boron nitride powder was hot pressed in an environment of metallic copper. When compared with a copper‐free system, the sintered body exposed to the copper was composed of substantially thicker grains having an unusual arrangement, consisting of preferred alignment of (0001) basal planes parallel to the pressure axis. The character of the orientation of the boron nitride grains substantially influenced the mechanical strength of the ceramics. The difference in the orientation of the grains is explained by the interaction between copper atoms and boron nitride crystals selectively occurring on the (0001) basal planes of the latter.

Ceramics were prepared by hot pressing of chemical mixtures of turbostratic boron nitride with copper. A positive effect of copper on boron nitride crystallization and densification has been found. Preferred orientation of boron nitride grains has been revealed in such ceramics, being opposite to general experience: the c-axis of boron nitride crystallites was arranged preferably within a plane perpendicular to the direction of uniaxial pressure. Such an arrangement is interpreted as a result of the uniaxial compression of the boron nitride grains extensively growing within the c crystallographic axis.