The structure and mechanical properties of Fe2AlMn single crystals

The microstructure and mechanical properties of off-stoichiometric single-crystal Fe₂AlMn have been investigated. After casting, the alloy contained two sets of thermal antiphase boundaries, (a/4)?111? and (a/2)?100?, which are attributed to the fact that the compound solidifies into a bcc structure and subsequently orders to a B2 structure and then a L2₁ structure respectively upon further cooling. Crystals strained under tension at room temperature in air at 1s^?1 showed 6% elongation, whereas specimens strained at 1?×?10^?5?s^?1 showed no elongation, indicating that the compound is 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 800?K, which is slightly below the L2₁–B2 transition temperature of 898?K. The slip systems were found to be ?111?{110} at room temperature and 800?K. Transmission electron microscopy observations showed fourfold-dissociated ?111? dislocations in specimens strained at room temperature but only paired ?111? dislocations in specimens strained at the peak temperature. The room-temperature yield strength of quenched specimens increased with increasing quench temperatures from 700 to 1100?K.