(1. 沈陽工業(yè)大學材料科學與工程學院，沈陽110870；
2. 貴州工程應用技術學院化學工程學院，畢節(jié) 551700；
3. 中航工業(yè)北京航空材料研究院航空材料檢測與評價北京市重點實驗室，
先進高溫結構材料國防科技重點實驗室，北京 100095)
摘 要: 通過組織形貌觀察和蠕變性能測定，研究了鍛造態(tài)高鈮TiAl合金的蠕變與損傷行為。結果表明：鑄態(tài)高鈮TiAl合金經等溫鍛造，層片晶團的平均尺寸由507μm減小到56.7μm。鍛造態(tài)高鈮TiAl合金在蠕變期間的變形主要發(fā)生在γ片層和等軸γ晶中，位錯運動至相界/晶界受阻并堆積，可形成位錯纏結或位錯列，提高位錯運動的阻力；其中，等軸γ晶粒中的位錯纏結可發(fā)生束集促進動態(tài)再結晶，形成細小亞晶結構。柏氏矢量為[101]和[011]的位錯分別在不同{111}面滑移形成位錯網，γ相中的蠕變位錯運動至位錯網，與其相互作用，可改變原來的運動方向，促進其攀移。蠕變后期，孔洞首先在等軸γ晶區(qū)域產生，并在該區(qū)域聚集、長大和擴展，直至發(fā)生合金的蠕變斷裂。這是高溫蠕變期間的損傷與斷裂機制。
關鍵字: 鍛造態(tài)高鈮TiAl合金；顯微組織；蠕變；變形機制；損傷特征
（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
