Ordering in carbide Mo2C

Crystal grains separated from Mo-C ingots, annealed in 2573-623 K range and quenched from 1873 K were investigated by X-ray diffraction method (monochromatic CuKα-radiation). Three modifications of initial HCP Mo2C carbide were established: disordered one at temperatures of above 1700 K and two oredered rhombic modifications below 1700 K with rhombic distortion of basic lattice of metal atoms with a=0.4730=C0, b0.6027 ∼ 2A0, c=0.5198 ∼ √3a0 nm (a0/c0)=aHCP(CHCP)), sp. gr. Pbcn on the low and c=0.9466=2c0, b=2.4152 ∼ 8a0, c=4.1675 ∼8√3 a0 nm on the upper boundary of Mo2C homogeneity region