Amorphization of Fe/Al: bulk and thin-film effects

The amorphous non-equilibrium state of the system Fe/Al is studied in bulk and thin-film systems. For bulk samples prepared by ion-beam mixing of laser-deposited multilayers, a bcc solid solution is found for alloys with up to 70 at. % Al. Around 75 at. % Al a Fe2Al5-like crystalline phase is found. An amorphous state with Fe2Al5-like short-range order is found for 80 at. % Al. In thin films, for example the amorphous Al-rich transition layer of a laser-deposited Fe/Al multilayer, the amorphous state can exist for up to 30 at. % Fe due to the high interfacial energy. By ion-beam mixing at low temperatures (about 140 K) an oversaturation with 40 at. % Fe can be achieved.