Nitrogen diffusion patterns on RE/sub 2/Fe/sub 17/ compounds, RE=Pr, Nd, Sm and Gd

The nitrogen diffusion patterns for several RE/sub 2/Fe/sub 176/ intermetallic compounds are studied. The nitriding process was done in both slabs and powder samples, which were characterized and analyzed thermomagnetically and metallographically. Thermographic analysis shows two phases: the pure 2:17 and the fully nitrided one for several nitrogen concentrations in all samples studied. Metallographic analyses confirm the presence of two phases. A broadening caused by stress or by dilution was detected for the pure phase transition. The nitriding process occurs by diffusion mechanisms: along preferential paths at low temperature and according to the shell-core model at higher temperatures.<
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