Ab-Initio Modelling of Point Defect-Impurity Interaction in Tungsten and other BCC Transition Metals

Ab-initio calculations have been performed to investigate systematically defect-impurity interaction in Tungsten and other bcc transition metals. It is found that the most stable configuration of C and N atoms is the octahedral interstitial site whereas O and H atoms are located in the tetrahedral configuration. For the particular case of bcc-W, the binding energies formed by the carbon and nitrogen atoms located at octahedral sites, and mono-vacancy on a nearest neighbor site are very large, 1.39 eV and 1.91 eV, respectively. Implication of these results of diffusion of point defects in tungsten is discussed and compared with the case of bcc-Fe.