In this work, in-situ high temperature electron back-scatter diffraction (HT-EBSD) was designed to investigate the phase transformation in Grade 1 commercially pure titanium (CP Ti). The transformation from α-Ti to β-Ti during the heating process mostly followed the Burgers orientation relationship (BOR). However, $\left\{11\overline{2}1\right\}$$<\overline{1}\overline{1}26>$tensile twinning was found to occur during the β-Ti to α-Ti transformation in the continuous cooling process, which led to the formation of Type 2 α-variants that defied the BOR. This was not reported before for CP Ti, while similar previous observations were all associated with Ti alloys containing β-stabilizer(s). We attribute this observation to the relatively fast cooling process (16 °C/s) where the lattice mismatch between the β-Ti and α-Ti phases has introduced a sufficiently large internal stress within a short time. Diffusional-displacive mixed transformation was proposed for the β-Ti to α-Ti transformation, which can reasonably explain the observations in this work.

在这项工作中，原位高温电子背散射衍射 (HT-EBSD) 旨在研究 1 级商业纯钛 (CP Ti) 的相变。加热过程中α-Ti向β-Ti的转变主要遵循伯格斯取向关系（BOR）。然而，$\left\{11\overline{\mathrm{2个}}\mathrm{1个}\right\}$$<\overline{\mathrm{1个}}\overline{\mathrm{1个}}26>$在连续冷却过程中，在 β-Ti 到 α-Ti 的转变过程中发现了拉伸孪晶，这导致了违反 BOR 的 2 型 α 变体的形成。之前没有关于 CP Ti 的报道，而之前类似的观察结果都与含有 β-稳定剂的钛合金有关。我们将此观察结果归因于相对较快的冷却过程 (16 °C/s)，其中 β-Ti 和 α-Ti 相之间的晶格失配在短时间内引入了足够大的内应力。针对 β-Ti 到 α-Ti 的转换提出了扩散-位移混合转换，这可以合理地解释这项工作中的观察结果。