IN-SITU OBSERVATION OF THE NITROGENATION OF SM2FE17 BY MEANS OF HIGH-TEMPERATURE X-RAY-DIFFRACTION

The mechanism of nitrogenation of Sm2Fe17 was investigated with in-sit u high temperature x-ray diffraction with Debye-Scherrer optic using a quartz capillary equipped with an additional buffer volume to supply sufficient nitrogen for the expected phase reaction. The formation of Sm2Fe17Nx with x approximate to 3 was observed at temperatures between 325 degrees C and 450 degrees C. During the phase transition period, taking 30-90 min at 450 degrees C and up to 300 min at 350 degrees C, two phases were observed simultaneously, a non-nitrided Sm2Fe17 phase and the already fully nitrided Sm2Fe17N3 phase. At 325 degrees C no si ngle-phase material could be obtained during 300 min. The resulting la ttice parameters measured after the complete nitrogenation are the sam e as those, obtained from the externally nitrogenized samples.