It was shown that the hardness and strength of LaB6-MeB2 composite ceramic materials were defined by the strength of interatomic bonds between the matrix and fibers, the mutual crystallographic orientations of the highest-strength directions in the matrix hexaboride and reinforcing diboride phases, the dimensions and number of reinforcing inclusions, and their stress-strain state. Increasing the fracture toughness by reinforcement with diboride fibers revealed the relationship between the hardness of the crystal faces, which decreased in the order: H(111) > H(110) > H (100). The surface energies were: σ(111) > σ(110) >σ (100).

Anisotropy of Microhardness of Directionally Crystallized Materials Based on Lanthanum Hexaboride. Loboda, P.I.: Materials Science, 1999, 35[4], 552-60