抄録
Ball-milling of elemental powder mixtures without external heat application has been utilized as a process for the mechanochemical synthesis of high melting compounds. The mixtures of chromium, molybdenum and amorphous boron elemental powders with atomic ratios Cr:Mo:B=(1-x):x:2(x=0-1.0) were comminuted for 10-40h in a planetary ball-mill, and a single hexagonal phase(Cr1-xMoxB2) was formed after 40h of milling using tungsten carbide balls. By annealing at 900-1400°C, a single hexagonal phase was still observed at the compositions of x=0-0.6. At x=0.8 and 1.0, the hexagonal phase was observed to be partly transformed to rhombohedral phase by annealing at the temperatures above 1300 and 1000°C, respectively. The variation in the lattice parameters of the hexagonal phase with x was estimated to differ from Vegard’s law because of a tendency toward superlattice formation. The rhombohedral phase was estimated to be Mo2B5-x type by the determination of lattice parameters.
