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 bee structure and subsequently orders to a B2 structure and then a L2(1) 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 x 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 L2(1)-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.