TiAl合金是一种极具潜力的轻质高温结构材料，但存在室温脆性大和服役温度低两大不足。新型PST TiAl单晶实现了强度、塑性和蠕变抗力的跨越性提升，其中纳米孪晶起到了关键作用。但纳米孪晶的种类、产生和分布，孪晶界面与位错运动对力学性能的影响规律尚不清楚。本项目旨在探明PST TiAl单晶中形变纳米孪晶产生的热力学与动力学机制，阐明纳米孪晶类型、分布及其对力学性能的影响规律，揭示孪晶界面的协调变形行为、孪晶与位错的交互作用及孪晶的高温失效退化机制。分别研究PST TiAl单晶在弹性变形阶段和塑性变形阶段中纳米孪晶和位错的运动，探究新型PST TiAl单晶强度与塑性比TiAl多晶合金同步大幅度提高的本质原因，为Ni-Al、Fe-Al等金属间化合物塑性和强度跨越提升提供借鉴。

TiAl alloys are promising light-weight structural materials used at high temperatures, but they are short of room-temperature ductility and high-temperature strength. The newly developed PST TiAl single crystals made a great improvement in strength, ductility and creep resistant, in which the nano-twins (NTs) played a key roal. However, the variety, formation and distribution of deformed NTs, the influence rules of NTS’ boundaries and dislocation movement on mechanical properties are still not clear to us. The purpose of this program is to explore the thermodynamics and dynamics mechanism of the formation of NTs, illustrate the variety, formation and distribution of NTs, reveal the coordinating deformation behavior of NTS’ boundaries, the interactions between NTs and dislocations and the degradation failure of NTs at high temperatures. We aim at clarifying the essential reason that why the newly developed PST TiAl single crystals owning a enormous increase in both strength and ductility compared with polycrystalline TiAl alloys, by studying the movement of NTs and dislocations in elastic and plastic deformation stage respectively, providing reference for the huge boost of ductility and strength of intermetallics such as Ni-Al and Fe-Al.