Abstract:The interface evolution of Ti/Ni multi-layered composites produced by 6 cycles accumulative roll bonding after heat treatment was investigated in this study. And the interfacial structural, chemical composition and phase transition temperature of Ti/Ni multi-layered composites with different heat treatment were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) and a differential scanning calorimeter (DSC). With the annealing time increased, the compounds formed by Ti/Ni interface diffusion transformed from unstable state to stable state, and the composition curves of Ti and Ni elements in the interface gradually change from a cross-steep ladder to two nearly straight parallel lines. With time increases, the microstructure of Ti-rich Ti/Ni composites treated at 720℃ transforming from a regular layered structure to a mixture structure with alternating TiNi and Ti2Ni layers. When the hold time is less than 10h, the structure of TiNi phase is composed of B19" with complex monoclinal structure and B2 with CsCl structure, while when the time is more than 10h, only B19" phase exists. In the process of cooling/heating, a good martensitic and reversible phase transition of A→M/M→A occurred in each sample. With the increase of time, the phase transition hysteresis (Ap-Mp) from 22.4 ℃ of the 1 h heat treatment sample increases to 31.9 ℃ of the 30 h sample.