Shape Memory effect and Superelasticity in the [001] Single crystals of a FeNiCoAlTa Alloy with γ–α′-Thermoelastic Martensitic Transformations

Using single crystals of a Fe – 28% Ni – 17% Co – 11.5% Al – 25% Ta (аt.%) alloy, oriented for tensile loading along the [001] direction, the shape-memory (SME) and superelasticity (SE) effects caused by reversible thermoelastic martensitic transformations (MTs) from a high-temperature fcc-phase into a bctmartensite are investigated. It is demonstrated that the conditions necessary for the thermoelastic MTs to occur are achieved by aging at 973 K within the time interval (t) from 0.5 to 7.0 hours, which is accompanied by precipitation of the γ′-phase particles, (FeNiCo) 3 (AlTa), whose d