中文摘要：

Alloy 617B镍基高温合金具有优良的长期高温服役性能,是目前先进超超临界发电技术锅炉管的主要候选材料。结合金相显微镜、扫描电镜、透射电镜等研究了Alloy 617B在750℃这3种应力条件下的持久蠕变行为及变形过程中材料的组织演化。研究结果表明,该合金750℃外推10^5h的蠕变断裂强度可达到约80MPa,蠕变断裂曲线呈典型的三阶段特征;随着应力减小,Alloy 617B合金持久蠕变试样的断口由穿晶向沿晶断裂转变,微裂纹、空洞的数量和尺寸也有所降低;初生M23C6的尺寸随蠕变时间的增长有所粗化,边缘有球化趋势,同时二次M23C6也逐渐增长变粗,分布更加广泛;γ＇相在断口附近的分布较少。

英文摘要：

Alloy 617B is defined as a solid-solution strengthened Ni-base superalloy with excellent long-term high temperature performance, and is also one of the most promising candidate materials for advanced ultra super critical （A-USC） applications, operating with steam target temperatures as high as 700-760℃ and pressures of 35- 37.5MPa. The present investigation concentrates on linking microstructural evolution of Alloy 617B to the creep deformation characterization at 750 ℃, by comparing the creep behavior at 3 different stress conditions with experimental data utilizing the optical microscopy （OM）, scanning electron microscope （SEM） and transmission electron microscope （TEM）. Results show that the 10^5h creep strength of Alloy 617B at 750 ℃ reaches 80MPa, and a typical creep curve with distinct primary, secondary, and tertiary creep stages was observed. The fracture surface shows the combined ductile transgranular and intergranular fracture modes; cavities and cracks decreases with lower stress condition and longer rupture time; both the primary and secondary M23C6 carbides experience a growing and coarsening progress, and only limited amount of γ＂ was observed.