The effects of aging temperature and time on the shape memory behavior of the high nickel-rich Ni54Ti46 (at.%) alloys were investigated. The changes in transformation temperatures, microstructure, lattice structure and mechanical behavior with aging were revealed. Multiple-stage phase transformation was observed for aged specimens due to the formation of Ti3Ni4, Ti2Ni3, and TiNi3 precipitates. It was revealed that the transformation temperatures can be tailored by aging where Ms was −3 °C after 550 °C–24 h aging and 29 °C after 400 °C–3 h aging. Aged samples showed a shape memory effect with a recoverable strain of <1.6% where 550 °C–3 h aged Ni54Ti46 alloy showed a maximum recoverable strain of 1.55% under 500 MPa. The maximum work output was determined as 7.75 J/cm3 for 550 °C–3 h aged Ni54Ti46 alloys. Partial shape recovery was also observed in aged samples.
- Mechanical properties
- Multi-stage phase transformation
- Shape memory alloys