(1. 沈阳工业大学 材料科学与工程学院，沈阳 110870；
2. 北京航空材料研究院，北京 100095)
摘 要: 通过蠕变曲线测定及组织形貌观察，研究[001]、[011]取向镍基单晶合金在蠕变期间的组织演化及变形特征。结果表明：经完全热处理后，[001]和[011]取向合金中立方γ′相均以共格方式镶嵌在γ基体相中，并沿 取向规则排列。蠕变期间，[001]取向合金中γ′相沿垂直于应力轴方向形成N-型筏状组织，而[011]取向合金中γ′相沿[001]取向形成纤维状筏形组织，且在(100)晶面的筏状γ′相与施加应力轴方向呈45°角排列，其中，立方γ′相不同晶面中扩张晶格的法线方向是筏状γ′相的生长方向。在试验温度和应力范围内，与[011]取向合金相比，[001]取向合金具有较好的蠕变抗力。在高温蠕变后期，两取向合金中的筏状γ′相均发生粗化和扭折，其中，[001]取向合金在蠕变后期的变形机制是位错剪切γ′相，而[011]取向合金的变形特征主要是形变位错在基体通道中滑移。
关键字: 单晶镍基合金；晶体取向；蠕变；组织演化；变形特征
single crystal nickel-based superalloy
（1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:By means of the measurement of creep curves and microstructure observation, the microstructure evolution and creep behaviors of [001] and [011] oriented single crystal nickel-base superalloy during tensile creep were investigated. The results show that, after fully heat treated, the microstructure of [001] and [011] oriented single crystal nickel-base superalloy consists of the cubical γ′ phase embedded coherent in the γ matrix and arranged regularly along the orientations. During creep, the cubical γ′ phase in [001] orientation alloy is transformed into the N-type rafted structure along the direction vertical to the applied stress axis. However, the cubical γ′ phase in [011] orientation superalloy is transformed into the strip-like rafted structure along [001] orientation during creep, and the orientation of the rafted γ′ phase is 45° relative to the direction of the applied stress axis on (100) crystal plane. Thereinto, the normal of the expanding lattice on the different crystal planes of the cubical γ′ phase is thought to be the growth direction of the rafted phase. In the ranges of the applied stresses and temperatures, compared to [011] orientation alloy, [001] orientation alloy has a better creep resistance and a longer creep life. In the later period of high temperature creep, the rafted γ′ phase in [001] and [011] orientations alloy is gradually coarsened and twisted. The dislocations shearing the rafted γ′ phase and slipping within the γ matrix channels are thought to be the deformation mechanisms of [001] and [011] orientations alloys, respectively.
Key words: single crystal nickel-base superalloy; crystal orientation; creep; microstructure evolution; deformation features
