An investigation was made of reactions ill the Zr - B - C system. The exist
ence of a eutectic in the quasibinary section B4C - ZrB2 was confirmed. A d
irectionally solidified eutectic alloy was obtained by zone melting. Its co
mposition was precisely determined as (mol, %) 71.5 B4C, 28.5 ZrB2 The effe
ct of melting parameters on the eutectic structure was studied.