Binary Fe-28 at.% Al alloys (Fe3Al-type) transform from B2→DO3 ordered phases at 550°C upon cooling. More complex Fe-28Al alloys can have B2↔DO3 transition temperatures that range from 530 to 670°C. The kinetics of the B2→DO3 ordered phase transition also appear to be affected by alloy composition and by matrix dislocation microstructure. The binary and Nb-containing ternary alloys have rapid B2→DO3 transition kinetics during cooling. However, the ternary or more complex alloys that contain Cr have relatively slower phase transition kinetics during similar cooling. Deformation of a complex Fe-28Al-5Cr alloy in the B2 phase regime creates a very high matrix dislocation concentration, which coincides with complete suppression of the B2→DO3 phase transition during cooling.