An investigation was made of the structure, solution and diffusion behavior of carbon in tungsten; based upon first-principles calculations. The single C atom was energetically favorable when sitting at the octahedral interstitial site, with a solution energy of 0.78eV in W. Double C atoms tended to be paired up at the two neighboring octahedral interstitial sites along the <210> direction with a distance of ~3.57Å and a binding energy of +0.50eV. This suggested that a positive attractive interaction between C atoms existed, which might lead to a local higher concentration of C in W and form carbides. Kinetically, the C and vacancy diffusion coefficients were determined as a function of temperature, and were 1.32 x 10-19 and 3.11 x 10-23m2/s at a typical temperature of 600K, respectively.

Dissolution and Diffusion Properties of Carbon in Tungsten. Y.L.Liu, H.B.Zhou, S.Jin, Y.Zhang, G.H.Lu: Journal of Physics - Condensed Matter, 2010, 22[44], 445504