中文摘要：

研究了一种含Re为4.0%～5.5%（质量分数）的实验型镍基单晶高温合金在不同定向凝固结晶条件下铸态的宏微观组织特征,分析了凝固结晶温度参数对单晶完整性、显微疏松与共晶含量、枝晶偏析等的影响。结果表明：高的熔体过热处理温度不仅促进合金元素分布的均匀化,同时降低了高Re和高难熔元素含量的单晶合金结晶缺陷的倾向性,提高了单晶完整性。合金熔体过热温度、铸型温度/浇注温度的适度提高有利于枝晶间的补缩,并减少显微疏松。

英文摘要：

The as-cast macrostructure and microstructure features for an experimental rhenium-containing（4.0%-5.5%（mass fraction）） Ni-base superalloy under different directional solidification conditions was investigated.And the effects of temperature parameters during directional solidification on the single crystal integrity,micro-porosity,（γ＋γ′） eutectic content and dendritic segregation were analyzed.The results indicate that the high melt superheating temperature not only promoted the homogenization of alloying elements,but also reduced the tendency to form defects in Ni-base single crystal superalloy containing both high Re and high levels of refractory elements.The melt feeding in the interdendritic region became more complete and the content of micro-porosity reduced with increasing the melt superheating temperature,mould temperature and casting temperature.