Formability and thermal stability of α' phase in (Fe1-y Coy)-(B, C, N) films

In order to find a way to obtain stable alpha"-Fe16X2 phase, the formability and thermal stability of alpha' (bct) phase were discussed. According to a rigid sphere model, we concluded that the less formability of B for the a' phase is due to its large atomic radius. We elucidated the difference of thermal stability of alpha'-Fe-X, taking into account their decomposition process. While, the decomposition of alpha'-Fe-N progresses only by the migration of N, without changing the bone structure of Fe lattice, the additional energy is needed to break the original alpha-Fe lattice in the cases of alpha'-Fe-B and alpha'-Fe-C. Therefore thermal stability of alpha'-Fe-B and alpha'-Fe-C is higher than that of alpha'-Fe-N. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.