中文摘要：

采用拉伸试验、扫描电镜、透射电镜等试验分析手段研究了K403镍基铸造高温合金在温度为800~950℃、时间为50~200 h热暴露后组织稳定性与性能的变化。结果表明：随着热暴露温度的提高,γ＇相聚集长大、边角发生钝化,γ＇相形貌由方形向圆形或近圆形转变,部分γ＇相发生定向排列连接粗化的现象越显著;合金仅在850和900℃热暴露条件下有少量有害的针状TCP脆性相（σ相）析出;随着热暴露温度的升高,合金抗拉强度下降幅度增大,延伸率呈上升趋势。其主要原因是由于γ＇相的粗化聚集和TCP相的析出。

英文摘要：

Microstructural stability and the corresponding property change of Ni-based superalloy K403 after thermal exposure were studied using scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and tensile test apparatus. The thermal exposure tests were carried out from 800 ℃ to 950 ℃ for 50 to 200 h. The results show that the γ＇ phases segregate and grow up with blunted corners, the shapes of γ＇ phases change form cube to sphere or nearly spherical shape, and parts of the γ＇ phase tend to coarsen due to the connection-oriented effect, which are more remarkable with increasing the thermal exposure temperature. While a small amount of needle-like brittle TCP （σ phase） precipitate only at 850℃ and 900 ℃. At the same time, as the thermal exposure temperature rising, the tensile strength of the alloy decreases more sharply, whereas ductility increases, due to the combinative effect of coarsened and aggregated γ＇ phases and precipitation of TCP phase.