(1. 沈阳工业大学材料科学与工程学院，沈阳110870；
2. 贵州工程应用技术学院化学工程学院，毕节 551700；
3. 中航工业北京航空材料研究院航空材料检测与评价北京市重点实验室，
先进高温结构材料国防科技重点实验室，北京 100095)
摘 要: 通过组织形貌观察和蠕变性能测定，研究了锻造态高铌TiAl合金的蠕变与损伤行为。结果表明：铸态高铌TiAl合金经等温锻造，层片晶团的平均尺寸由507μm减小到56.7μm。锻造态高铌TiAl合金在蠕变期间的变形主要发生在γ片层和等轴γ晶中，位错运动至相界/晶界受阻并堆积，可形成位错缠结或位错列，提高位错运动的阻力；其中，等轴γ晶粒中的位错缠结可发生束集促进动态再结晶，形成细小亚晶结构。柏氏矢量为[101]和[011]的位错分别在不同{111}面滑移形成位错网，γ相中的蠕变位错运动至位错网，与其相互作用，可改变原来的运动方向，促进其攀移。蠕变后期，孔洞首先在等轴γ晶区域产生，并在该区域聚集、长大和扩展，直至发生合金的蠕变断裂。这是高温蠕变期间的损伤与断裂机制。
关键字: 锻造态高铌TiAl合金；显微组织；蠕变；变形机制；损伤特征
（1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;
2. School of Chemical Engineering, Guizhou University of Engineering Science, Bijie 551700, China;
3. Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation, Laboratory of Science and Technology on Advanced High Temperature Structural Materials, AVIC Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:The deformation and damage behavior of the forged TiAl alloy with high Nb content during creep were investigated by means of microstructure observation and creep properties measurement. The results show that the average grain size of the lamellar colonyof as-cast TiAl alloy with high Nb content may diminish from 507μm to 56.7μm by isothermal forging technology. The deformation of forged alloy during creep mainly occurs in γ lamellar and equiaxed γ grain. The dislocations slipping to phases interfaces and grain boundaries are hindered for piling up, and the formation of dislocation tangle or dislocation sequence can increase the resistance of dislocation motion. Wherein, the dislocation tangles in the equiaxed γ grain can generate bundle aggregation to promote dynamic recrystallization and form fine sub-grain structure. The dislocations with burgers vectors of [101 and [011] slip on the {111} planes to form the networks. When the creep dislocations in the lamellar γ phases move to the networks, they will interact with the dislocation networks, and change the original moving direction to promote the climbing of dislocations. In the latter stage of creep, the holes or cracks are firstly initiated in the equiaxed γ grain and propagated in this region until creeping fracture, which is the damage and fracture mechanism of alloy during creep at high temperature.
Key words: forged TiAl alloy with high Nb content; microstructure; creep; deformation mechanism; damage features
