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 degree C for the specimen aged at 500 degree C for 4h.