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800h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 microstructure evolution of a nickel based single crystal after thermal exposure at 1070 ℃ for different time was investigated.The results show that the alloy consists of the regular and cube γ'phase and γphase after full heat treatment.The γ'coarsening and the γmatrix channel broadening are observed after thermal exposure at 1 070 ℃.There is no topological close-packed (TCP) phase precipited in matrix after thermal exposure for 200 h.Needle-shaped TCP phase precipitates in dendritic core of the alloy after thermal exposure for 400 h.The microstructure of alloy presents full γ'rafting structure after thermal exposure for 800 h.With increasing thermal exposure time,the amount of TCP phase increases and it grows from the dendritic core to the interdendritic region.TCP phase consists of σ phase containing Re,W,Mo and Co,etc,and TCP phase precipitates and grows along fixed direction of [012]σ//[001]γ and (110) σ// (2(2)0) γ.
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