温度对镍基单晶高温合金SRR99持久各向异性行为的影响

摘要

In order to reveal the temperature dependence of anisotropic stress-rupture behavior of SRR99 single crystal superalloys under conditions of temperature ranging from 650 to 1 040 ℃ and typical stresses,fracture morphologies and microstructure evolution were investigated by SEM and TEM.From the Larson-Miller curves,it is found that single crystal with [001] orientation has the optimum stress rupture property in comparison with [011] and [ 111] orientations at lower and intermediate temperature.With increasing temperature to 1 040 ℃,stress-rupture properties of single crystals with three principal orientations tend to be equivalent.Based on the fracture surface and microstructural observations,superior stress-rupture behavior of single crystal with [001] orientation was rationalized and the effect of misorientation of single crystal on stress rupture property was also discussed.%为了揭示单晶高温合金SRR99在650-1 040℃温度范围内及典型应力条件下的持久各向异性行为,采用扫描电镜和透射电镜对持久实验后试样的断口形貌和微观组织演化进行研究.从Larson-Miller曲线看出,在中低温条件下,[001]取向单晶具有最好的持久性能,而[011]和[111]取向的持久性能相差不大；随着温度的升高,3个主取向的持久性能的差异逐渐缩小,到1 040℃时几乎相同.通过断口形貌和组织观察,分析[001]取向单晶持久性能较佳的原因,同时探讨取向偏离度对[001]取向单晶持久性能的影响.