Pseudoelasticity and slip reversibility in DO₃−ordered Fe–Al single crystals by<i>in situ</i>experiments

Abstract

Abstract In situ straining experiments in the optical and electron microscope have been performed in DO3−ordered single crystals of Fe–Al alloys at room temperature and for Al contents in the range 21–25 at.%. These alloys are known to exhibit pseudoelasticity at room temperature and a shape memory effect at low temperatures. The results of in situ observations show that this behaviour has to be attributed to reversible glide on {110} planes of α/2〈111〉 superpartial dislocations leaving antiphase boundaries behind them. This hypothesis is quantitatively discussed and criteria are proposed for the occurrence of slip reversibility (Bauschinger effect) in alloys with suitable antiphase boundaries or stacking fault energies.