Post-aging cooling rate effects in Ni45.3Ti34.7Hf15Pd5 shape memory alloys

© 2020 Elsevier LtdEffects of post-aging cooling rate (water quenched, WQ, and furnace cooled, FC) on the shape memory properties of polycrystalline Ni45.3Ti34.7Hf15Pd5 alloys were studied. Their functional properties such as transformation temperatures, hysteresis, elastic energy, superelastic behavior and recoverable strain were found to be closely related to the post-aging cooling rate. Martensite start temperature decreased from 77 °C for WQ sample to 22 °C for FC sample. Impressive shape memory effect was observed under a huge compressive stress of 1 GPa with recoverable strains of 2.2 % and 2.5 % for the water quenched and furnace cooled samples, respectively. While both WQ and FC alloys showed perfect superelasticity for a wide temperature range, the WQ sample showed superelasticity at higher temperatures above 100 °C