High-temperature superelasticity of Ni50.6Ti24.4Hf25.0 shape memory alloy

Changes in transformation temperatures and high-temperature mechanical behavior of the new Ni50.6Ti34.4Hf25.0 alloy were determined after selected aging treatments. Differential scanning calorimetry was used to compare the homogenized, solution-treated and aged specimens for a wide combination of aging temperatures and times. Isothermal deformation experiments were conducted measuring reversible transformation strains with digital image correlation. Extraordinary superelasticity was found at test temperatures up to 300 °C for the specimen aged at 500 °C for 4 h.