(1. 沈陽(yáng)工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，沈陽(yáng) 110870；
2. 沈陽(yáng)化工大學(xué) 機(jī)械工程學(xué)院，沈陽(yáng) 110142；
3. 北京航空材料研究院，北京 100095)
摘 要: 通過(guò)蠕變曲線的測(cè)定及微觀組織形貌觀察，研究[111]取向鎳基單晶合金在高溫低應(yīng)力條件下的組織結(jié)構(gòu)與蠕變行為。結(jié)果表明：經(jīng)完全熱處理后，[111]取向單晶合金的組織結(jié)構(gòu)是立方γ′相以共格方式嵌鑲在γ基體中，并沿 方向規(guī)則排列；在1 040~1 080 ℃、137~180 MPa的溫度和應(yīng)力范圍內(nèi)，該取向單晶合金表現(xiàn)出明顯的溫度和施加應(yīng)力敏感性。蠕變期間，γ′相沿與應(yīng)力軸呈一定角度形成筏狀組織，蠕變后期在近斷口區(qū)域筏狀γ′相發(fā)生粗化和扭折。[111]取向單晶合金在蠕變期間的變形特征是位錯(cuò)在γ基體通道中運(yùn)動(dòng)和剪切筏狀γ′相，由于形變量較大，較多位錯(cuò)切入筏狀γ′相后使其形成亞晶結(jié)構(gòu)，其中，蠕變后期大量位錯(cuò)切入筏狀γ′相導(dǎo)致合金的蠕變抗力降低，是合金發(fā)生蠕變斷裂的主要原因。
關(guān)鍵字: 單晶鎳基合金；[111]取向；蠕變；組織演化；亞晶；變形特征
（1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;
2. School of Mechanical Engineering, Shenyang University of Chemical Technology, Shenyang 110142, China;
3. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:By means of the measurement of creep curves and microstructure observation, the microstructure and creep behavior of a [111] orientation single crystal nickel-base superalloy were investigated under the conditions of high temperatures and low stresses. The results show that, after full heat-treatment, the microstructure of [111] oriented single crystal nickel-base superalloy consists of the cuboidal γ′ phase embedded coherently in the γ matrix, and regularly arranges along the orientations. In the temperature and stress ranges of 1 040−1 080 ℃ and 137−180 MPa, the superalloy displays an obvious sensibility to the applied temperatures and stresses. During the tensile creep, the cuboidal γ′ phase in the alloy is transformed into the rafted structure at a certain angle relative to the direction of the applied stress. Furthermore, the coarsening and distorting of the rafted γ′ phase occurs in the region near the fracture at the latter stage of creep. The deformation features of the [111] orientation single crystal superalloy during creep are that the slipping of the dislocations is activated in the γ matrix channels and dislocations shear into the rafted γ′ phase. The significant amount of dislocations shear into the rafted γ′ phase, due to the bigger strain occurred to the alloy, to form the subgrain structure during high-temperature creep. In the latter stage of creep, large number of dislocations shear into the rafted γ′ phase for decreasing the creep resistance, which is thought to be the main reason for the creep rupture of the alloy.
Key words: single crystal nickel-base superalloy; [111] orientation; creep; structure evolution; subgrain; deformation feature
