Some peculiarities of eutectic crystallization of LaB6-(Ti, Zr)B2 alloys

The structures of eutectic LaB(6)(Ti, Zr)B(2) alloys are studied after directional crystallization. The eutectic compositions and monovariant equilibrium between two quasibinary eutectics in this system were determined. Varying the TiB(2)/ZrB(2) borides ratio permits us to control in their solid solutions the corresponding cell dimensions and, consequently, the boron-boron distances in the resulting quasibinary borides, Our previous assumptions that the perfectness of the real structure is determined by differences in the distances between boron atoms in boron sublattices of hexa- and diboride phases were confirmed. It is shown that forming the regular whiskers structure is much easier for complex (Ti,Zr)B(2) boride than for individual TiB(2) or ZrB(2) borides, (C) 2000 Academic Press.