The microstructure of Ti

51.7 Ni

24.5 Cu

23.8 shape memory alloy ribbons prepared by rapid solidification has been observed in the conditions of spinning and annealing respectively. The results show that microstructure of as-spun ribbons is mainly composed of amorphous phase embedded with a small amount of crystalline particles that is indexed by B2 or B19. B19 martensites variants show various morphologies such as needle

coarse plate

strip and hook. The initial crystallization temperature of 436 ℃ can be observed and the crystallization activation energy of 444.7 kJ/mol of the as-spun ribbons can be determined by the Kissinger’s equation at a heating rate of 5 ℃/min by DSC linear scanning. Crystallization structure of the ribbon is mainly composed of single-pair variant B19 martensites

in which there exist two pairs of variants self-accommodated with perpendicular orientation in some particle

and the absence of the hook-like martensite variants can be found and new martensite is preferred to nucleate at the grain boundary to growth towards grain

with annealing at 400 ℃.