Effect of proportion of γ́-Fe₄N in compound layer produced during plasma nitriding on diffusion coefficient of lanthanum

The diffusion of lanthanum in ε and γ phases during plasma nitriding with La addition was studied and diffusion coefficient in close-packed nitride layer was also calculated. The x-ray diffraction pattern indicated that the compound layer is composed of the mono-phase, dual ones or mono one. The results showed the diffusion of lanthanum into the compound layer produced by plasma nitriding to a significant depth which increases with increasing time or temperature. Increment in the proportion of mono one phase resulted in the increase of diffusion coefficient of La in compound layer for the same treatment time at a given temperature.