The microstructure and mechanical properties of off-stoichiometric single crystals were investigated. After casting, the alloy contained 2 sets of thermal antiphase boundaries: (a/4)<111> and (a/2)<100>. These were attributed to the fact that the compound solidified in a body-centered cubic structure, and then ordered into a B2 structure and a L21 structure upon further cooling. Crystals strained under tension at room temperature in air at 1/s exhibited 6% elongation. Specimens which were strained at 10-5/s exhibited no elongation; thus indicating that the compound was sensitive to the testing environment. Fracture occurred on {100} in both cases. Compression tests showed that a yield anomaly was present at intermediate temperatures, with the peak yield strength occurring at about 800K. This was slightly below the L21-B2 transition temperature (898K). The slip systems were found to be <111>{110} at room temperature and 800K. Transmission electron microscopic observations revealed fourfold-dissociated <111> dislocations in specimens which were strained at room temperature, but only paired <111> dislocations were seen in specimens which were strained at the peak temperature. The room-temperature yield strength of quenched specimens increased with increasing quench temperature, from 700 to 1100K.

The Structure and Mechanical Properties of Fe2AlMn Single Crystals. M.Wittmann, I.Baker, P.R.Munroe: Philosophical Magazine, 2004, 84[29], 3169-94