Microstructure evolution, dominated by the formation of deformation-induced ${\alpha }^{″}$ martensite during the 3-point bending of a metastable $\beta$ Ti–10V–2Fe–3Al alloy containing 5% $\alpha$, was observed in-situ using forward-scatter electron imaging and electron backscattering diffraction. ${\alpha }^{″}$ plates nucleated heterogeneously from ${\left\{580\right\}}_{{\alpha }^{″}}$ habit planes at $\alpha$-$\beta$ interfaces and triggered the nucleation of additional ${\alpha }^{″}$ plates at the advancing interface during growth and upon impingement with high-angle boundaries. Further thickening of the impinged ${\alpha }^{″}$ plates led to a build-up of strain energy which induced $\left\{130\right\}3\overline{1}{0}_{{\alpha }^{″}}$ twinning within obstacle-forming ${\alpha }^{″}$ plates. Until now, this twinning system was observed in Nb and Ta alloyed Ti shape memory alloys only. This in-situ study is also the first to document the activation of $\left\{130\right\}3\overline{1}{0}_{{\alpha }^{″}}$ twinning by ${\alpha }^{″}$ impingement in a metastable $\beta$ matrix. The first forming variants were ${\left\{011\right\}}_{{\alpha }^{″}}$ compound twin-related variant pairs, each forming from up to two individual habit planes. These variant pairs were consistently predicted by determining the grain-average stress with finite element analysis and computing the available work from the transformation strain of the ${\alpha }^{″}$ variants. At higher indenter loads, grains that were unfavourably oriented to martensite formation accommodated the local stress by forming aggregates of different ${\alpha }^{″}$ variants, obeying either ${\left\{111\right\}}_{{\alpha }^{″}}$ type I or ${211}_{{\alpha }^{″}}$ type II twin relationships. Scanning transmission electron microscopy revealed ${\alpha }^{″}$ substructures comprising columnar domains oriented perpendicular to the habit plane along with the absence of lattice invariant deformation. The growth of ${\alpha }^{″}$ plates involved ledge formation at ${\alpha }^{″}$-$\beta$ interfaces.

微观结构演变，主要由形变诱发的形成 ${\alpha }^{\text{'}\text{'}}$ 亚稳三点弯曲过程中的马氏体 $\beta$ 含5％的Ti-10V-2Fe-3Al合金 $\alpha$，使用前向散射电子成像和电子反向散射衍射原位观察。 ${\alpha }^{\text{'}\text{'}}$ 异质核板 ${\left\{580\right\}}_{{\alpha }^{\text{'}\text{'}}}$ 习惯于 $\alpha$--$\beta$ 接口并触发了附加的成核 ${\alpha }^{\text{'}\text{'}}$在生长过程中以及受到大角度边界撞击时，在前进界面处的板块。进一步加厚${\alpha }^{\text{'}\text{'}}$ 板导致应变能的积累，从而引起 $\left\{130\right\}3\overline{\mathrm{1个}}{0}_{{\alpha }^{\text{'}\text{'}}}$ 在障碍物形成中孪生 ${\alpha }^{\text{'}\text{'}}$盘子。迄今为止，仅在Nb和Ta合金化的Ti形状记忆合金中观察到这种孪生系统。这项原位研究也是第一个记录激活$\left\{130\right\}3\overline{\mathrm{1个}}{0}_{{\alpha }^{\text{'}\text{'}}}$ 结对 ${\alpha }^{\text{'}\text{'}}$ 冲击在亚稳态 $\beta$矩阵。第一个成型变体是${\left\{011\right\}}_{{\alpha }^{\text{'}\text{'}}}$复合的双胞胎相关变体对，每个变体对最多由两个独立的习惯平面组成。通过使用有限元分析确定晶粒平均应力，并根据合金的转变应变计算可用功，可以一致地预测这些变体对。${\alpha }^{\text{'}\text{'}}$变体。在较高的压头载荷下，不利于马氏体形成的晶粒通过形成不同的聚集体来适应局部应力${\alpha }^{\text{'}\text{'}}$ 变体，服从 ${\left\{111\right\}}_{{\alpha }^{\text{'}\text{'}}}$ I型或 ${211}_{{\alpha }^{\text{'}\text{'}}}$II型双胞胎关系。扫描透射电子显微镜显示${\alpha }^{\text{'}\text{'}}$子结构包含垂直于习性平面定向的柱状畴，并且不存在晶格不变变形。的成长${\alpha }^{\text{'}\text{'}}$ 板块涉及壁架形成 ${\alpha }^{\text{'}\text{'}}$--$\beta$ 接口。