为进一步提高燃机叶片的服役温度，获得综合性能更优的镍基单晶高温合金，本工作研究了Ta含量对镍基单晶高温合金在900℃长时热暴露过程中组织损伤和性能退化规律的影响。利用SEM和TEM-EDS分析了Ta含量对抗热腐蚀镍基单晶高温合金微观组织及900℃、275 MPa 蠕变性能的影响。通过对比相同热暴露时间的不同Ta含量合金(2Ta、5Ta和8Ta)组织发现，随Ta含量的增加，γ'相尺寸无明显变化，但立方度有所提高，γ基体中的三次γ'相数量减少。随Ta含量由2%增加到5%，除热暴露4000 h时2种合金γ'相体积分数较为接近外，其余热暴露时间下5Ta合金的γ'相体积分数均高于2Ta合金；Ta含量进一步增加至8%，热暴露不同时间后γ'相体积分数均有所增加。随热暴露时间的延长，3种合金的900℃、275 MPa蠕变性能变化趋势存在差异：2Ta合金热暴露0~4000 h无明显变化，热暴露8000 h后性能明显降低；5Ta和8Ta合金的持久寿命均随热暴露时间的延长先升高后降低，分别在热暴露500和2000 h时达到峰值。随Ta含量的增加，合金稳态蠕变速率不断降低、蠕变寿命明显延长、峰值蠕变寿命向后推移，同时蠕变断后γ'相筏化程度和筏排结构完整度明显提高。合金蠕变性能的提升归因于蠕变初始状态中γ'相体积分数的提高、蠕变过程中γ'相筏排结构完整度和厚度的增加等综合因素。

Innovative, massive gas turbines have emerged as critical equipment for achieving the goals of energy conservation and the development of new clean energy sources. As the inlet temperature of industrial gas turbines continues to rise, the high-temperature capabilities of hot corrosion-resistant single-crystal turbine blades should be enhanced. This work investigates the effects of Ta on the microstructural stability and creep properties of hot corrosion-resistant Ni-based single-crystal superalloys with varying Ta contents (2Ta, 5Ta, and 8Ta) during long-term thermal exposure at 900^oC. The findings revealed that after various thermal exposure times, the addition of Ta had no observable influence on the size of γ' precipitates, but it considerably increased the cubic degree of γ' precipitates and continuously decreased the number of tertiary γ' precipitates in γ matrix. With the increase of Ta content from 2% to 5%, the volume fraction of γ' precipitates of 5Ta alloy is higher than that of 2Ta alloy except that which is close to each other when thermal exposure at 4000 h. In addition, the volume fraction of γ' precipitates increased was higher than that of 2Ta and 5Ta alloys, as the Ta content increased from 5% to 8% after various thermal exposure times. The creep lives of the three alloys at 900^oC and 275 MPa exhibited different trends as thermal exposure time increased; there was no obvious fluctuation in the 2Ta alloy after thermal exposure from 0 to 4000 h, but it significantly decreased after thermal exposure at 8000 h; the creep lives of the 5Ta and 8Ta alloys increased initially and then decreased, and the peak creep lives were 500 and 2000 h, respectively. With the addition of Ta, the steady-state creep rate continuously decreased, the creep life significantly increased, and the peak creep life shifted backward. Simultaneously, the degree and structural integrity of the rafted γ' precipitates after creep rupture increased steadily. Hence, the improvement of the creep life of the alloys was attributed to a combination of factors, such as the increase in the volume fraction of the γ' precipitates in the initial state of the creep, the increase in rafted structural integrity, and thickness of the rafted γ' precipitates during the creep process.