CHARACTERIZATION OF THE SURFACE-LAYER OF VARIOUS METALS IMPLANTED WITH NITROGEN

The surface layers of various metals (Al, Ti, V, Fe, Ni, Co, Cu, Zr, Nb, Mo, Sn, Ta and W) which were implanted with nitrogen at doses of 3 x 10(17) and 1 x 10(18) N cm-2 were analysed by means of Rutherford backscattering spectrometry and X-ray diffraction. For the lower dose, metal in the implanted layer was partially nitrided. In some targets (V, Ti, Zr and Ta) a solid solution was created, accompanying an isotropic enlargement of the lattice for the cubic metal (V, Ta) and an anisotropic c-direction enlargement for the hexagonal metal (Ti, Zr). When an amount of nitrogen large enough to saturate the implanted region of the targets was implanted, the most stable nitride was created in this region, and the amount of retained nitrogen increases with a decrease of the heat of formation of the nitride. This result shows that retention of nitrogen in the target is affected strongly by the reactivity of the metal to nitrogen.