Abstract In order to improve the functional stability of Ti-50.8 at.% Ni alloys, a new plastic deformation method and device suitable for sheets or wires was developed in this work, called “stretching-bending deformation (SBD)”. After SBD process, aging treatments were carried out at various temperatures (523–823 K) and various durations (0.5–12 h) to explore the effects of SBD process and aging treatment on the phase transformation behavior and superelasticity of NiTi alloys. The results indicate that the repeated stretching-bending process is an effective method to improve the functional stability of NiTi alloys, which introduces a certain amount of dislocations and refines the grain size from 9.1 μm in as-annealed state to 3.2 μm in the state after 15 SBD passes. After repeated SBD treatment, the martensitic transformation occurs in a wide temperature range, and the phase transformation peak becomes wider. Aging at 623 K for 0.5–1 h after 7 SBD passes helps to improve the functional stability. This is due to refined grains with an average grain size of 5.4 μm and favorable dislocations introduced by SBD and nanoscaled Ni4Ti3 precipitates (

中文翻译：

---

拉伸弯曲变形和时效处理对Ti-50.8 at.% Ni合金相变行为和超弹性的影响

摘要 为了提高Ti-50.8 at.% Ni合金的功能稳定性，本文开发了一种适用于板材或线材的塑性变形方法和装置，称为“拉伸弯曲变形（SBD）”。SBD 工艺后，在不同温度（523-823 K）和不同时间（0.5-12 h）下进行时效处理，以探索 SBD 工艺和时效处理对 NiTi 合金相变行为和超弹性的影响。结果表明，重复拉伸弯曲工艺是提高 NiTi 合金功能稳定性的有效方法，它引入了一定量的位错，使晶粒尺寸从退火态的 9.1 μm 细化到退火态的 3.2 μm。 15 SBD 通过。经过反复SBD处理，马氏体相变发生在较宽的温度范围内，相变峰变宽。经过 7 次 SBD 后，在 623 K 下老化 0.5-1 小时有助于提高功能稳定性。这是由于平均晶粒尺寸为 5.4 μm 的细化晶粒以及 SBD 和纳米级 Ni4Ti3 沉淀物引入的有利位错（