CRYSTAL-STRUCTURE OF CARBON-IMPLANTED TITANIUM, VANADIUM AND CHROMIUM

The dose dependence on crystal structures and lattice parameters of ca rbon-implanted layers of polycrystalline titanium, vanadium and chromi um plates has been investigated by X-ray diffraction (XRD) measurement s. Implantations of C-12(+)-ions were performed at doses between 1 x 1 0(17) and 2 x 10(18) ions/cm(2) at 100 keV, and at room temperature. T he formation of titanium carbide is characterized only in the B1(NaCl) -type structure in the entire implant dose range, and its lattice para meter mostly agrees with that of monocarbide TiC at higher doses. For vanadium, the B1-type carbide grows preferentially with the dose incre ment. Its lattice parameter suggests the formation of nearly monocarbi de V4C3 at the highest dose. For chromium, only a cubic carbide peculi ar to carbon implantation, of which the lattice of chromium atoms is f ee having lattice parameter equal to the diagonal line segment size of the bce lattice, is found to crystallize at doses over 5 x 10(17) ion s/cm(2). Carbides of titanium and vanadium formed by carbon implantati on correspond to those expected by a standard equilibrium with the sys tem of carbon and the respective metal. The formation process of a par ticular phase will be discussed for chromium carbide.