Abstract The interface structure of {2 2 ‾ 01} α2-Ti3Al deformation twins formed during tensile deformation of polysynthetically twinned (PST) TiAl single crystals at 900 °C has been studied systematically by aberration-corrected scanning transmission electron microscopy. Numerous superlattice intrinsic stacking faults (SISFs) are formed on the (0001) basal plane of α2 twins, thereby resulting in the formation of steps on the twin boundaries. The height of steps equals to the spacing of the (2 2 ‾ 01) twinning plane. The basal-plane SISFs formed in α2 twins can't be attributed to the glide of Shockley superpartial dislocations. Lattice correspondence analyses based on classical twinning theory reveal that complex atomic shuffle and interchange shuffling are responsible for the formation of twinning and basal-plane SISFs in α2 twins. In addition, basal-plane antiphase boundaries (APB) are formed at the vicinity of α2 twin tips to relieve the stress concentration imposed by misfit dislocations.

中文翻译：

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多合成孪晶TiAl单晶中{22‾01}α2-Ti3Al变形孪晶界面结构的原子尺度研究

摘要 通过像差校正扫描透射电子显微镜系统研究了多合成孪晶 (PST) TiAl 单晶在 900 °C 拉伸变形过程中形成的 {2 2 ‾ 01} α2-Ti3Al 变形孪晶的界面结构。在α2孪晶的（0001）基面上形成了许多超晶格本征堆垛层错（SISF），从而导致在孪晶边界上形成台阶。台阶的高度等于 (2 2 ‾ 01) 孪晶面的间距。在α2孪晶中形成的基面SISF不能归因于肖克利超偏位错的滑移。基于经典孪生理论的晶格对应分析表明，复杂的原子洗牌和交换洗牌是 α2 孪晶中孪晶和基面 SISF 形成的原因。