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研究了一种镍基单晶高温合金在1 070℃热暴露不同时间后的组织变化。结果表明:合金的热处理组织由立方化较好γ’相和基体γ相组成。经过1 070℃热暴露处理后,γ相基体通道宽度增加,γ’强化相合并长大;热暴露200 h后,合金没有析出不稳定相(TCP相)。热暴露400 h后,少量TCP相开始在枝晶干区域以细针状的形态析出。经过800 h处理后,显微组织呈现出明显的筏排结构。随热暴露时间增加TCP相析出量明显增多,并由枝晶干范围向枝晶间区域生长。TCP相含有Re、W、Mo和Co等合金元素,衍射分析为σ相,与合金基体取向关系为(110)_σ∥(220)_γ,[012]_σ∥[001]_γ。
The microstructures of a single-crystal nickel-base superalloy were investigated after thermal exposure at 1 070 ℃ for different time. The results show that the microstructure of the alloy consists of cubic γ phase and γ matrix. After heat exposure at 1 070 ℃, the channel width of γ phase matrix increased and the γ ’enhanced phase merged and grew up. After 200 h heat exposure, the phase of the amorphous phase was not precipitated (TCP phase). After 400 h heat exposure, a small amount of TCP phase began to precipitate in the form of fine needles in the dendrite dry area. After 800 h treatment, the microstructure showed obvious raft structure. With the increase of heat exposure time, the precipitates of TCP phase increased obviously and the dendrites grew from the dendrites to the interdendritic regions. The TCP phase contains alloying elements such as Re, W, Mo and Co. The diffraction analysis is σ phase and the orientation relationship with the matrix is (110) _σ // (220) _γ, [012] _σ∥ [001] _γ.