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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。
The effects of annealing at 850 ℃ on the microstructure, phase transformation characteristics and shape recovery of the ferrule of Ti-50.84at% Ni alloy were investigated by differential scanning calorimetry (DSC), XRD and optical microscopy. The results show that the as-cast and annealed microstructure of Ti-50.84at% Ni alloy is dominated by Ni-Ti matrix (B2), while for forging, the Ni-Ti matrix martensitic phase Lord, all three states contain a small amount of Ni4Ti3 phase. After annealed at 850 ℃, Ni4Ti3 phase is reduced and finely dispersed, resulting in large inverse transformation stress and increasing Ni content in the matrix, resulting in a significant reduction of the martensitic transformation temperature (Ms) Phase change separation. High temperature annealing eliminates dislocations and other defects in the alloy is conducive to the anti-phase transformation of martensite, thereby increasing the shape recovery rate and recovery force of the hoop.