The influence of heat treatment on mechanical properties of austenitic NiTi alloys during impact loading is studied in this paper. Hot-rolled rod samples were annealed at 800 °C for 5 h to obtain homogenized texture. After homogenization, samples were aged at 500 °C and 550 °C for 1–4.5 h. Fine and/or coarse Ni₄Ti₃ precipitates disperse homogeneously or heterogeneously in grain interior and at grain boundaries depending on aging temperatures and time. The high strain rate compressive behaviors of austenitic NiTi SMAs after various heat treatments were investigated using a Kolsky (split Hopkinson) compression bar. The phase transformation temperatures were determined by differential scanning calorimeter (DSC). The microstructures of the samples were studied by scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). It is observed that the initial stress for phase transformation, work hardening during phase transformation, and transformation temperatures vary with heat treatments. The initial stress for martensitic transformation increases with increasing heating temperature and time. Ni₄Ti₃ precipitates are shown to improve the pseudoelasticity of NiTi SMAs during impact loading.

研究了冲击载荷作用下热处理对奥氏体NiTi合金力学性能的影响。将热轧棒材样品在800°C退火5 h，以获得均质的织构。均质后，将样品在500°C和550°C下老化1–4.5 h。细和/或粗Ni ₄ Ti ₃根据时效温度和时间的不同，析出物在晶粒内部和晶界均匀或不均匀地分散。使用Kolsky（霍普金森分裂）压缩棒研究了各种热处理后奥氏体NiTi SMA的高应变率压缩行为。相差温度通过差示扫描量热仪（DSC）确定。通过扫描电子显微镜（SEM）和电子背散射衍射（EBSD）研究了样品的微观结构。可以看出，相变的初始应力，相变过程中的加工硬化以及相变温度随热处理而变化。马氏体相变的初始应力随着加热温度和时间的增加而增加。镍₄钛_{显示了3种}沉淀物可改善冲击载荷过程中NiTi SMA的拟弹性。