Point defect concentrations of impurity carbon in tungsten

Our recent investigations (Y.-L. Liu, H.-B. Zhou, Y. Zhang, G.-H. Lu, G.-N. Luo, Comput. Mater. Sci. 50 (2011) 3213) show that impurity carbon (C) easily bonds onto vacancy internal-surface and a monovacancy is capable of trapping as many as 4 C atoms to form C _nV complexes in W, but the concentration distributions of point defects such as C _nV complexes are lacking. Based on first-principles calculations combined with statistical model, we predict point defect concentrations of impurity C in W and find that the concentration of vacancy in the form of C _nV complexes notablely increase with the presence of C, although the concentration of interstitial C is still higher than that of C _nV complexes in W. We believe that the present method can be also generally applicable for predicting the concentration distribution of other impurities in other metals and metal alloys.