The reaction between niobium and graphite was investigated at 1700 to 2300C. Parabolic growth behaviour was observed for the Nb2C and NbC phases. It was demonstrated that niobium atom diffusion in the carbides was negligible, compared to that for carbon. The carbon diffusivity in NbC was given by:

D(cm2/s) = 7.6 exp[-88.2(kcal/mol)/RT]

W.F.Brizes, L.H.Cadoff, J.M.Tobin: Journal of Nuclear Materials, 1966, 20[1], 57-67