Pseudoelastic behaviour of Fe3Al single crystals with D03 structure

Pseudoelasticity which shape memory alloys reveal is generally based on a thermoelastic martensitic transformation. However, Fe-rich Fe3Al single crystals with the D03 structure demonstrate pseudoelasticity regardless of the martensitic transformation. It is strongly suggested that the pseudoelasticity of Fe3Al crystals originates from the peculiar dislocation motion dragging an antiphase boundary (APB). During loading, a 1/4〈111〉1/4〈111〉 superpartial dislocation moves individually dragging the APB. On the other hand, the APB pulls back the superpartial during unloading due to its tension resulting in the pseudoelasticity of which recoverable strain is as much as 5%. Hence, this phenomenon is called “APB pseudoelasticity”. This article summarizes the recent progress in the understanding of the pseudoelastic behaviour of D03-ordered Fe3Al single crystals and the effects of Al concentration, deformation temperature, loading axis and third element addition are discussed.