A Mössbauer study of plasma nitrided iron

Abstract

Iron powder has been nitrided in a glow discharge plasma of a mixture of nitrogen and hydrogen, in order to verify the existence of a metastable iron nitrogen solid solution, previously observed from the Sm2Fe17N3 phase decomposition process. Our results show that, for short nitridation times, we obtain a mixture of Fe4N, a small amount of α-Fe and an iron nitrogen solid solution the amount of which increases after heat-treatment at 610 °C. This iron nitrogen solid solution is characterized by Mössbauer spectroscopy which shows a typical α-Fe spectrum, but with lower hyperfine field and broader linewidth. TMA measurements show that the Curie temperature is similar to that of α-Fe.