The self-diffusion properties of carbon in UCx, where x ranged from approximately 1 to 2, were described in terms of an fcc lattice gas model in which C2 groups attracted only when they were nearest neighbors. A modified Monte Carlo method was used to calculate the self-diffusion coefficient as a function of x and temperature. The diffusion coefficient went through a maximum at about UC1.2 for 2380, 2500, 2600 and 2650K. The activation enthalpy for diffusion increased non-uniformly from approximately 54kcal/mol (reference point) at compositions close to UC, to about 75kcal/mol for compositions near to UC2. The functional form of this variation was in satisfactory agreement with existing experimental data.

Diffusional Aspects of Non-Stoichiometry a Model for UCx. G.E.Murch, R.J.Thorn: Philosophical Magazine, 1977, 35[6], 1441-51