NiTi合金支架定型及力学性能的研究

his paper used successive short duration thermal treatments for shape setting of NiTi braiding stent. The effect of heat treatments on A_f temperature was studied. The NiTi wire behavior, in terms of mechanical properties and superelasticity, was evaluated by stress-strain cycle curves. The influence of thermal inertia on the heat treatment was also considered. With the first heat treatment (400℃,30min), the A_f point could be increased to handle easily the martensitic malleable stent material at ambient temperature. The second heat treatment (550℃,15min) on a three-dimensional mold decreased the A_f point to 8℃ to get a very elastic austenitic structure. Undergoing the successive short duration thermal treatments, the stent unit can reach maximal recoverability and excellent non-linear superelasticity.