【摘要】 采用扫描电子显微镜（SEM）和透射电子显微镜（TEM），研究了新型铁镍基铸造高温合金在高温蠕变过程中的微观组织演变和力学性能变化。研究表明，在高温蠕变过程中，合金的显微组织经历了显著变化，特别是在晶内和晶界析出相的粗化与演变。随着蠕变时间的延长，晶内的γ’相逐渐粗化，体积分数增大；晶界处的粗大、短棒状γ’相由零星分布转为针状相聚集呈链，进而导致晶界附近局部析出相贫化区的形成。此外，晶界析出了少量的σ相和一定量TiC相，并且在晶界处伴随蠕变时间的延长也逐渐粗化形成链状结构。合金样品的高温蠕变断裂主要是由于晶界滑移和晶界附近析出相贫化区的变形局部化和裂纹萌生所导致，析出相的演变是引发沿晶断裂的主要原因。随着蠕变的延续，合金的硬度提升了13.0%，但其断后延伸率大幅下降。本研究为新型铁镍基合金的长期稳定性、热处理工艺以及服役性能的评估提供了宝贵的数据支持和理论基础。更多还原

【Abstract】 The microstructural evolution and mechanical property changes of a novel Fe-Ni based cast superalloy during high-temperature creep at 650 °C are investigated, utilizing scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results indicate that the microstructure of the alloy has undergone significant changes, especially in the evolution of precipitates within grains and at grain boundaries. With prolonged creep exposure, the γ’ phase within the grains undergoes coarsening, with an increase of volume fraction. At the grain boundaries, the coarse, rod-like γ’ phase transitions from a dispersed to a needle-like morphology, which eventually forms a chain-like structure, leading to the development of precipitate-free zones around the grain boundaries. Simultaneously, a small amount of σ phase and a certain amount of TiC precipitates form at the grain boundaries and coarsen over time. The high-temperature creep fracture of the alloy specimens is primarily attributed to the local deformation and crack initiation at the PFZs near grain boundaries, which are caused by grain boundary sliding. The evolution of precipitates serves as the main factor triggering intergranular fracture. These precipitate changes contribute to the initiation of intergranular fractures. Despite an increase of hardness by 13.0%, the alloy exhibits a significant decrease in elongation after fracture. These findings underscore the effect of microstructural evolution on the alloy’s high-temperature mechanical properties, providing valuable data and theoretical support for evaluating the long-term stability, heat treatment processes, and service performance of the novel Fe-Ni based cast superalloy.更多还原