Effect of ordering process on giant pseudoelasticity in Fe_3Al single crystals

摘要

Pseudoelasticity in Fe_3Al single crystals with the D0_3 structure was investigated focusing on the ordering process and the ordered domain structure. During unloading, a plastic strain of 5.0 percent was perfectly recovered in Fe-23.0 at. percent Al single crystals with an appropriate heat treatment, while Fe-28.0 at. percent Al crystals exhibited little strain recovery. The ordered domain structures in slowly cooled Fe-23.0 at. percent Al and Fe-28.0 at. percent Al were different from each other depending on their ordering process. In Fe-23.0 at. percent Al, the strong interaction between specific domain boundaries and superpartial dislocations with Burgers vector of 1/4 led to the individual motion of the superpartials dragging an antiphase boundary (APB). The surface tension due to the APB resulted in the pseudoelasticity in Fe-23.0 at. percent Al single crystals. In addition, APB created by an intersection between the domain boundaries and the superpartials also pulled back the superpartials during unloading. A refinement of ordered domains was effective in enhancing the pseudoelasticity in Fe_3Al crystals.