Ion beam induced phase transformation in Fe-Mn bilayers: a Mossbauer study

Ion-beam mixing of Fe-Mn bilayers induced by 100 keV krypton ions in the dose range (0.1-15) x 10(15) ions/cm(2) has been studied by means of conversion electron Mossbauer spectroscopy and X-ray diffraction. The results indicate that a dose of about 1 x 10(15) Kr+/cm(2) is sufficient to induce an appreciable mixing between the two atomic species. The alpha-Fe(Mn) solid solution presents a maximum at this dose, while at higher doses also the epsilon and gamma Fe-Mn phases are formed in an appreciable amount. Heating of irradiated samples evidences the metastable character of epsilon phase and favours the growth of the terminal structures alpha-Fe(Mn) and alpha-Mn(Fe) of the Fe-Mn equilibrium phase diagram.