Influence of Tensile Training Conditions on Shape-Memory Properties of NiTi-Based Ribbons

This work presents a study of the mechanical properties and influence of thermomechanical training conditions on the two-way shape-memory effect (TWSME) (magnitude and stability) in NiTi and NiTiCu alloys. Correlation with a stress-assisted two-way shape-memory effect (SATWSME) was also investigated. A rapid solidification technique was employed for preparation of small-dimension NiTi samples with homogeneous microstructure. Samples were fabricated by melt spinning. The melt-spun ribbons were trained under tensile deformation by thermal cycling through the phase transformation temperature range. Results showed that the tensile trainings under both constant strain and constant stress were effective in developing a TWSME. The SATWSME was comparable in magnitude to the TWSME. Addition of copper was effective in narrowing the transformation hysteresis and transformation temperature dependence on composition.