Clarification of the origin of fatigue softening and one variant ωphase in binary Ti-Nb based biomaterial alloys

Ti-xNb合金对β相的稳定性具有成分依赖性。低β相稳定性的Ti-xNb合金表现出反常的电阻率温度依赖性、低的德拜温度和弹性软化。因此，可以通过控制β相的稳定性来降低这些合金的杨氏模数。β相的稳定性对TixNb合金的塑性变形也有影响。低β相稳定性的Ti-xNb合金表现出S-S曲线特征。这意味着ω相是通过位错运动而析出的。疲劳实验表明，这种现象在Ti-xNb合金单晶中表现得更为明显。此外，我们还发现，ω相的析出导致了反常软化。

Ti-xNb alloys have the composition dependence of the phase stability of βphase. The Ti-xNb alloy with low βphase stability exhibits anomalous temperature dependence of the electrical resistivity, low Debye temperature and elastic softening. Thus, it can be reduced the Young’s modulus by controlling βphase stability in these alloys. The βphase stability also effect on the plastic deformation in Ti-xNb alloys. The Ti-xNb alloy with low βphase stability exhibits characteristics S-S curve. This means that the ωphase is precipitated by motion of dislocation. This phenomena more clearly appear in Ti-xNb alloy single crystal by fatigue experiments. Moreover, we found that the precipitation of ωphase leads to anomalous softening.