Shape Memory Effects and Work Output of [001] Ni₅₅Fe₁₈Ga₂₇ Single Crystals in Torsion Mode

The work output of [001] Ni₅₅Fe₁₈Ga₂₇ single crystals was studied under different loading conditions (cooling under 0, 30, 70 and 100 MPa and heating under 150 MPa) in torsion mode. It was shown that during thermal cycling, the functional properties, such as martensitic transformation temperatures, shape memory effect value and work output, of Ni₅₅Fe₁₈Ga₂₇ single crystals stabilized after a few thermal cycles and then barely varied. A maximum work output of 1.15 MJ/m³ was found when the sample was cooled without stress or under a stress of 30 MPa and heated under a stress of 150 MPa. Simultaneously, it was observed that if the stress that was acted on cooling was 30 MPa, then less plastic strain appeared in the sample during thermal cycling.