一种试验第三代单晶高温合金1100℃长期时效组织演化

Microstructural Evolution of an Experimental Third Generation Single Crystal Superalloy after Long-term Thermal Exposure at

摘要:

通过1100℃长期时效100-800小时，研究了一种试验第三代单晶高温合金组织演化规律，结果表明：随着时效时间的增加，枝晶干γ‘相逐渐变得粗大和不规则；而枝晶间γ’相形貌则随着时效时间的延长呈规则立方、合并长大、筏排化规律演化。枝晶干与枝晶间这种不同的γ‘相演化规律主要由合金元素的偏析造成。时效300小时后，枝晶干析出了少量的针状TCP相，随着时效时间增加，枝晶干处TCP相析出量增加；枝晶间直到800小时仍未发现TCP相析出；TEM和EDX分析表明析出相为σ相，富含Re、W元素。

Abstract:

The effects of thermal exposure on microstructure of an experimental third generation single crystal superalloy were investigated. The alloy was exposed at 1100℃ for 100-800 h. The γ′ particles in dendrite core gradually had coarsened and became very irregular by γ′ precipitates dissolving resulting from elements diffusion with increasing exposure time. The γ′ precipitates in interdendritic region varied from cuboidal morphology, fusing together, and rafting with the increase of exposure time. The various γ′ particles behaviors between dendritic core and interdendritic region were attributed to the segregation of refractory elements. After 300h a small amount of needle-shaped TCP phases were found in dendrite core and the mount of TCP phases increased with increasing exposure time. There was no TCP phase in interdendritic region until 800h. TEM and EDX measurements showed that TCP phases observed in these samples were identified as σ phase enriched Re and W elements.