Formation of γ-Fe by mechanical alloying of Cu-Fe?

A study of the low temperature magnetic behavior of a metastable fcc-FeCu solid solution obtained by mechanical alloying as well as of the subsequent annealed product is conducted. The metastable solid solution is ferromagnetic, and it has a temperature dependence of the magnetization which follows a T^3/2 law. During annealing, the metastable phase decomposes into Cu and Fe phases. It is found that the low temperature magnetization of this subsequent mixture decreases with respect to that of the fcc solid solution. The Mossbauer spectrum obtained shows a paramagnetic Fe phase with the same relative resonant area as the percentage of the decrease in magnetization. These results suggest that after the annealing process, not all the iron is found in the stable and ferromagnetic bcc or α phase, but a noticeable proportion probably remains as fcc particles of γ-Fe