Measurement of N and C diffusion in Sm2Fe17 by magnetic relaxation

Magnetic after-effect (MAE) measurements of nitrided and carburized Sm2Fe17 compounds were performed in the temperature range of 140 K to 480 K. Both nitrided and carburized compounds show relaxation maxima at 285 and 300 K, respectively, which are absent in pure Sm2Fe17 compounds. Therefore, these relaxation maxima are attributed to jumps of interstitially dissolved nitrogen or carbon atoms. Numerical evaluation yielded an activation enthalpy QN (0.84±0.05) eV and a pre-exponential factor τ0N=3.10-15±1 s for the short-range diffusion of N atoms. The corresponding values for the carbon diffusion are QC=(0.91±0.05) eV and τ0C=1.10-15±1 s. The carbon and nitrogen content of the samples was determined from the increase in mass during nitrogenation or carburization to Sm2Fe17N1.2 and Sm2Fe17C2.6. (orig.)