Orientation Dependence of the Two-Way Shape Memory Effect in Single Crystals of Co₃₅Ni₃₅Al₂₈Fe₂ Alloy

The orientation dependence of the two-way shape memory effect (TWSME) in stress-induced martensite aged Co₃₅Ni₃₅Al₂₈Fe₂ (B2 + γ') single crystals has been studied. Aging leads to the stabilization of the oriented L1₀-martensite, which helps to induce the TWSME. By orientation variation of the single crystal, one can stabilize the twinned or detwinned martensite, which determines the regularities of the TWSME manifestation. In the aged [001] crystals, the twinned L1₀-martensite variant is stabilized. The TWSME in the [001] crystals develops with a large (−2.4%) reversible strain in the temperature range of 57–60 K and with a narrow (45 K) hysteresis, while the stabilization of the detwinned L1₀-martensite variant during aging in [110] crystals facilitates the development of a smaller TWSME value (−1.6%) in narrow ranges of 3–9 K, with a wide (79 K) hysteresis.