Low-temperature iron-nitride phase transformations induced by ion bombardment

We show that for the Fe-N system the combined use of ion irradiation and thermal annealing can lower the temperature for a given phase transformation. By Ar bombarding N-implanted Fe samples at 250 and 300 degrees C, we have induced the epsilon-Fe2N double right arrow epsilon-Fe2+xN+epsilon-Fe3.2N and the epsilon-Fe2N double right arrow epsilon-Fe3N+gamma'-Fe4N phase transformations, respectively. These temperatures are 50 degrees C lower than the ones needed to produce the same transformations by thermal annealing. (C) 1996 American Institute of Physics.