The inter-diffusion of carbon (originating from a graphite substrate) into a niobium coating and the fabrication of its carbides by heat treatment in the temperature range of 1073-1773 K was studied. The thickness of the Nb2C and NbC phases formed after heat treatment as well as the interdiffusion coefficients for the formation of the carbide layers were also studied. It was found that the carbide layer growth displayed parabolic behavior patterns inherent in the growth rate constants (K) of Nb2C and NbC layers. By assuming that the inter-diffusion coefficients are independent of concentration, it was possible to determine the inter-difflasion coefficients of carbon D-c into Nb2C and NbC layers as a function of temperature. (c) 2005 Elsevier B.V. All rights reserved.