A Film-Thickness Determination of Nitrogen Diffusion in Zirconium Nitride

Calculations of the diffusion coefficient for nitrogen in zirconium nitride are given in terms of a unidirectional, two‐phase, volume‐diffusion model. These calculations require the knowledge of both the thicknesses of nitride films and of nitrogen diffusion coefficients in the underlying zirconium metal. The values obtained can be represented by for the temperature range of 650°–850°C. Zirconium nitriding kinetics for extended exposures up to 900 hr are also reported. The portion of nitrogen confined to the α‐zirconium phase amounts to about 80 w/o of the total nitrogen consumed during the over‐all nitriding process.