Microstructures and mechanical properties of Ti-45 at.%Ni-5 at.%Cu alloy ribbons containing Ti2Ni particles

Microstructures, shape memory characteristics and the superelasticity of Ti-45Ni-5Cu (at.%) alloy ribbons were investigated by transmission electron microscopy, thermal cycling tests under constant load and tensile tests. Coherent Ti2Ni particles less than 13 nm in diameter are formed when the melt spinning temperature is higher than 1773 K. The ribbons with coherent Ti2Ni particles do not show a residual elongation, which may be ascribed to the increase due to the coherent Ti2Ni particles of the critical stress for slip deformation by the coherent Ti2Ni particles. Almost perfect superelastic recovery is found in the ribbons containing coherent Ti2Ni particles, while only partial superelastic recovery is observed in Ti2Ni particle-free ribbons.