研究了固溶热处理对一种Re含量为6.5%（质量分数）的第三代单晶高温合金组织及持久性能的影响，实验结果表明：合金铸态下存在明显的凝固偏析，枝晶间区域存在大量的（γ+γ'）共晶组织。固溶过程中，共晶组织在1 335℃以上开始快速溶解，但难熔元素，尤其是Re元素的偏析需要在1 360℃以上才能有明显改善；经过1 365℃固溶后疏松含量增加至0.21%（体积分数），接近铸态下疏松含量的5.2倍。铸态及经1 360℃和1 365℃固溶热处理后合金的持久性能测试结果显示：固溶热处理显著改善了合金的持久性能，且固溶温度越高，持久性能越高。在高温持久加载过程中，铸态合金的裂纹主要沿枝晶间分布，在（γ+γ'）共晶组织处萌生；当固溶温度较低时，且枝晶干处析出了较多的TCP（topologically close-packed）相，未能充分降低Re元素的偏析可能是导致枝晶干处TCP相大量析出的主要原因；当固溶温度较高时，TCP相析出量较少。

Effect of solution heat treatment on microstructures and stress rupture properties of a third generation Ni-based single crystal superalloy with content of 6.5%(mass fraction) Re has been investigated. The experimental results show that the as-cast alloy exists significant solidification segregation and a large percentage of (γ+γ') eutectic. During the solution heat treatment, the (γ+γ') eutectic initially solves rapidly when the temperature is higher than 1 335℃. However, the solidification segregation especially the segregation of Re is not significantly reduced until solution heat treatment temperatures exceed 1 360℃. The micropore content after solution heat treatment at 1 365℃ is about 0.21%(volume fraction), which is 5.2 times of that before heat treatment. The stress rupture properties of the as-cast alloy and the alloys after different solution heat treatment at 1 360℃ and 1 365℃ are investigated respectively at the conditions of 1 080℃/190 MPa, 1 100℃/140 MPa and 1 150℃/83 MPa. The results show that the heat treatment significantly improves the stress rupture properties, and the higher solution heat treatment temperature is, the longer the stress rupture lives are. During the process of high temperature stress rupture, most of cracks distribute in the interdendritic and cracks initiat from the (γ+γ') eutectic in the as-cast alloy. The alloy with solution heat treatment at 1 360℃ has some cracks which distribute both in the dendritic core and interdendritic area. A large amount of TCP(topologically close-packed) precipitation distributes in the dendritic core possibly due to the residual segregation of Re. However, as the alloy with solution heat treatment at 1 365℃, there is less TCP precipitation.