Dergi makalesi Açık Erişim

Effects of aging temperature and aging time on the mechanism of martensitic transformation in nickel-rich NiTi shape memory alloys

2020    Kaya, I; Karaca, H. E.; Nagasako, M.; Kainuma, R.

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 M-s, was -3 degrees C after 550 degrees C-24 h aging and 29 degrees C after 400 degrees C-3 h aging. Aged samples showed a shape memory effect with a recoverable strain of < 1.6% where 550 degrees 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/cm(3) for 550 degrees C-3 h aged Ni54Ti46 alloys. Partial shape recovery was also observed in aged samples.