Channeling study of carbon atom location in Re-Cx and Ni-Cx systems

The location of carbon atoms and the structure of Re-Cx and Ni-Cx systems with carbon concentrations ranging from 0.003 to 0.015 and from 0.0018 to 0.0043, respectively, have been studied by use of the 1753 keV proton-channeling method and the resonant nuclear reaction 13C(p,γ)14N. At a carbon concentration x≤0.007 in the Re-Cx system, the impurity atoms are located in octahedral interstitial sites of rhenium. As the impurity content grows up to ≅0.01, the carbon atoms are displaced to other lattice sites. A further impurity concentration growth up to 0.015 results in carbon precipitation. For the Ni-Cx system at x≅0.0018 the carbon atoms are located in regular interstitial sites of nickel. With the increase of the impurity content up to 0.0043, the process of carbon precipitation takes place. (orig.)