中文摘要：

用示差扫描热分析（DSC）、XRD、光学显微镜等方法研究了850℃退火对Ti-50.84at%Ni合金紧箍环显微组织、相变特征和形状恢复率的影响。结果表明,Ti-50.84at%Ni合金锻造态和退火态组织都以Ni-Ti基体母相（B2）为主,而锻造后深冷处理则以Ni-Ti基体马氏体相（B19′）为主,3种状态都含有少量的Ni4Ti3相。850℃退火后,合金中Ni4Ti3相减少且细小弥散,产生了较大的反相变应力,并增加了基体中的Ni含量,使得合金的马氏体转变温度（Ms）明显降低,且与R相变分离。高温退火消除了合金中的位错等缺陷有利于马氏体逆相变的进行,从而提高了紧箍环的形状恢复率和恢复力。

英文摘要：

The effect of high temperature annealing treatment at 850 ℃ on microstructure, transformation and shape recovery rate of Ti-50. 84at% Ni shape memory alloy ring was studied by DSC, XRD and optics-microscope. The results show that microstructure of the forged and annealed Ti-50. 84at% Ni alloys is rich in Ni-Ti-parent-phases （B2） ,but the deep-cooled alloy is rich inNi-Ti-martensite（ B19′）, and all of them have a small quantity of Ni4Ti3. After annealing at 850 ℃, the NinTi3 precipitates become finer and less, which brings high anti-transformation stress and increases Ni content in the matrix. This leads that martensite transformation temperature （Ms）of the alloy is decreased and martensite transformation is separated from R transformation. The high temperature annealing eliminates the high-density dislocation defect in Ti-50. 84at% Ni alloy, which is propitious for martensite reverse-transformation, so it improves the shape recovery rate and restoring force of Ti-50. 84at% Ni alloy ring.