Effect of B addition on the superelasticity in FeNiCoAlTa single crystals

The study focuses on the superelastic effect in single-crystalline boron-doped Fe-based shape memory alloys. homogenized and quenched single crystals were subjected to a heat treatment at 973 K for variable aging times. As result, small coherent nanometer-sized γ′ (Ni 3 Al-type) precipitates formed. It was established that Fe-28Ni-17Co-11.5Al-2.5Ta-0.05B oriented along [001] direction exhibit fully reversible behavior up 14.3% compression strain 77 reaching maximum theoretical value. boron addition suppressed completely formation of brittle β phase reduced average precipitate size precipitates. Using high-energy synchrotron radiation high-resolution transmission electron microscopy analysis volume fraction determined indicating both factors are critical obtaining largest reversibility. Boron counters initial mechanical stabilization which detected without boron. Unlike thermally induced martensitic transformation, applied stresses produce different austenite/martensite interface composed interchanging austenite martensite variants. is also demonstrated upon loading/unloading cycles moving transformation front divides material into three district regions i.e. variant austenite, intermixed with martensite. • Fe28Ni17Co11.5Al2.5Ta0.05B 14.3%. B about 3–4 nm. stabilization. A very as compared observed.