X-RAY STRUCTURAL STUDIES OF NITROGEN DIFFUSION IN DY2FE17

The reaction between N2 and Dy2Fe17 has been studied by thermopiezic analysis on 20-25 μm sized powders in the temperature range 400-500°C. Partially nitrided powders were analyzed using CuKα x-ray diffraction and thermomagnetic techniques. Both high angle x-ray and thermomagnetic data show only the presence of Dy 2Fe17 and Dy2Fe17N 3-δ (δ<0.3) with no evidence of intermediate compositions. The results of the x-ray diffraction experiments at several Bragg peaks were simulated using a two phase model structure: a Dy2Fe 17 core with a Dy2Fe17N3 surface layer. The results show that at low temperatures the nitride layer is too thin to account for all of the nitrogen absorbed by the sample, indicating that a significant amount of the nitrogen diffused into the core of the particles, presumably along grain boundaries.