Martensitic transformation and mechanical properties of Ti-rich Ti-Ni-Cu melt-spun ribbon

Abstract Martensitic transformation, mechanical and thermomechanical properties of a Ti-rich Ti 52 Ni 23 Cu 25 melt spun ribbon annealed at a temperature below the crystallization temperature were studied by XRD, DSC and DMA. After annealing the initially amorphous ribbon at 400 °C for 10 h, the ribbon is fully crystallized and exhibits one-stage B 2↔ B 19 phase transformation with the temperature hysteresis of 14 °C. The annealed ribbon is composed of B 2, B 19 and B 11-TiCu phase with (001) preferential orientation. On the stress―strain curves, the rearrangement of the martensite variants and stress-induced martensitic transformation are observed below the M f temperature and above the A f temperature, respectively. The annealed ribbon exhibits up to 1.6% superelastic shape recovery with small stress hysteresis of 25 MPa. No flat stress-plateau is associated with the superelasticity. The annealed ribbon shows a well-defined shape memory effect during thermal cycling from −60 to 100 °C. The transformation strain and recovery strain increase with increasing the applied external stress. Under the external stress above 150 MPa, the shape recovery strain is not sensitive to it and keeps stable at about 1.74%.