Effects of Several Factors on the Ductility of the Ti-Ni Alloy

研究了ni浓度、试验温度、M_S温度和热处理对Ti-Ni合金塑性的影响。进行了拉伸试验以测量延伸率（断裂应变）。这主要是用来衡量延性。为了了解上述因素对塑性的影响，对所有情况下诱发滑移变形和马氏体的临界应力进行了测量。在MS温度、室温和473K下，1273K固溶处理试样的伸长率随ni浓度在50% ~ 52at%范围内的变化而变化。伸长率随ni浓度的增加而降低；当Ni含量为50at%时，伸长率最高约为70%，而当Ni含量为52at%时，伸长率最低约为10%。在任何ni浓度下，M.的伸长率都是最大的，而473K的伸长率最小。由于在473K变形时没有发生马氏体相变，因此还发现马氏体相比母相更具延展性。在77 ~ 473K的不同温度下得到的伸长率表明，固溶处理试样在M_S附近的伸长率最大；例如，在M_S附近，Ti-51at%Ni分别为70%，77K时为50%，473K时为24%。而经时效处理的富镍试样的伸长率与温度无关，在任意温度下伸长率均在20%左右。上述结果将主要在滑移变形的临界应力方面得到合理化。

The effects of the following several factors on the ductility of the Ti-Ni alloy have been investigated : Ni-concentration, test temperature, M_S temperature and heat-treatment. Tensile tests have been carried out for measuring the elongation(fracture strain), . which was mainly used as the measure of the ductility. The critical stresses for inducing slip deformation and martensites were measured for all cases in order to understand the effects of the above factors on the ductility.The elongation was measured in specimens solution-treated at 1273K as a function of Ni-concentration ranging from 50 to 52at% at the MS temperature, room temperature and 473K, respectively. The elongation decreased with increasing Ni-concentration ; the maximum elongation being about 70% for 50at%Ni, while the minimum being about 10% for 52at%Ni. The elongation obtained at M., was always the largest for any Ni-concentration, while the elongation at 473K was the smallest. Since the martensitic transformation does not occur at 473K during deformation, it was also found that the martensite phase is more ductile than the parent phase. The elongation obtained at various test temperatures ranging from 77 to 473K showed that the elongation at around M_S was the maximum for the solution-treated specimen ; for example, 70% around M_S, 50% at 77K and 24% at 473K, respectively, for the Ti-51at%Ni. However, the elongation of the age treated Ni-rich specimen did not show any test temperature dependence, the elongation being about 20% at any test temperature.The above results will be shown to be rationalized mainly in terms of the critical stress for slip deformation.