LOW-TEMPERATURE IRON-NITRIDE PHASE-TRANSFORMATIONS INDUCED BY ION-BOMBARDMENT

We show that for the Fe-N system the combined use of ion irradiation a nd thermal annealing can lower the temperature for a given phase trans formation. By Ar bombarding N-implanted Fe samples at 250 and 300 degr ees C, we have induced the epsilon-Fe2N double right arrow epsilon-Fe2 +xN+epsilon-Fe3.2N and the epsilon-Fe2N double right arrow epsilon-Fe3 N+gamma'-Fe4N phase transformations, respectively. These temperatures are 50 degrees C lower than the ones needed to produce the same transf ormations by thermal annealing. (C) 1996 American Institute of Physics .