Thermomechanical-cycling processes were applied to a metastable Ti-23Nb-0.7Ta-2Zr-1.0O (at%) alloy to control a volume fraction of mechanical twins, resulting from activation of twinning-induced plasticity effects. Analysis of the microstructure features designed using electron backscattering and X-ray diffraction revealed the deformation bands induced by the cycling process were characterized as only {332}< 113 >_β twinning. It was also observed that the fraction of twins was significantly increased with increasing the number of the cycles in the process, resulting in a pronounced softening effect. To shed a light on the relevant micro-scale features (e.g., geometric orientation and stress concentrations) responsible for the microstructure evolution and mechanical response, the local Schmid factor of grains and geometrically-necessary dislocation densities were evaluated from experimentally observed results, and correlated with deformation twinning. A good correlation between the local geometric Schmid factor and softening behavior, due to texture evolution within twins was established, as well as the effect of local stress concentrations on microstructure evolution of this Ti-Nb Gum metal. Significant decrease in micro-hardness (approximately 18% from untwinned structure) was achieved by highly twinned structure, and a possible deformation mechanism was established to enhance ductility without evident elastic properties variation in metastable β Ti alloys.

将热机械循环工艺应用于亚稳态Ti-23Nb-0.7Ta-2Zr-1.0O（at％）合金，以控制由孪生引起的可塑性效应的激活而产生的机械孪晶的体积分数。使用电子反向散射和X射线衍射设计的微观结构特征分析表明，循环过程引起的形变带仅表征为{332} <113> _β结对。还观察到，随着该过程中循环次数的增加，孪晶的分数显着增加，从而导致明显的软化效果。为了阐明负责微观结构演变和机械响应的相关微观尺度特征（例如，几何取向和应力集中），从实验观察到的结果中评估了晶粒的局部施密特因子和几何上必要的位错密度，并进行了相关性分析。与变形孪生。由于孪晶内部的织构演变，以及局部应力集中对这种Ti-Nb口香糖金属的微观结构演变的影响，建立了局部几何Schmid因子与软化行为之间的良好相关性。