Microstructures and mechanical properties of Ti-25Ni-25Cu (at.%) alloy ribbons

Microstructures, mechanical properties, the shape memory characteristics and the superelasticity of melt-spun Ti-25Ni-25Cu (at.%) alloy ribbons have been investigated by means of optical microscopy, transmission electron microscopy, X-ray diffraction, differential scanning calorimetry, thermal cycling tests under constant load and tensile tests. Fully amorphous Ti-25Ni-25Cu alloy ribbons were obtained under a linear velocity of 51 m/s and a melt spinning temperature of 1803 K. Some precipitates were formed at grain boundaries or in grains when the as-spun ribbons were annealed at temperature higher than 773 K. The maximum fracture strain (4.6%) was obtained from the ribbons annealed at 738 K which did not contain any precipitates