热处理对一种抗热腐蚀单晶高温合金组织和持久性能的影响

Effect of Heat Treatment on Microstructures and Stress Rupture Properties of Hot-Corrosion Resistant Single Crystal Superalloy

研究了热处理对一种抗热腐蚀单晶高温合金微观组织及1070℃/140 MPa持久性能的影响。结果表明:长时间的均匀化热处理显著降低了元素偏析;随着均匀化时间的延长,微孔面积分数逐渐增加,平均尺寸不断增大,微孔的密度呈先升高后降低的变化趋势;随一级时效温度的升高,γ′相尺寸逐渐增大,γ′相面积分数先增加后减少;合金的持久寿命随一级时效温度的提高先升高后降低,一级时效温度为1100℃时,立方状γ′相尺寸约370 nm且正方度较好,γ′相的面积分数最大,持久寿命最高;持久断口具有韧性断裂特征,亚晶界处的碳化物和微孔是引起持久试样断裂的主要裂纹源。

The effects of heat treatment on the microstructures and rupture properties at 1070℃/140 MPa of a hot-corrosion resistant single crystal superalloy were investigated.The results show that long-term homogenization heat treatment significantly reduces element segregation.With prolonging the homogenization time,the area fraction of micropores is gradually increased,the average size keeps increasing,and the density of micropores is increased firstly and then decreased.With increasing the primary aging temperature,the size ofγ'phase is enlarged gradually,and the area fraction ofγ'phase is firstly increased and then decreased.The stress rupture life of the alloy is increased firstly and then decreased with increasing the primary aging temperature.When the primary aging temperature is 1100℃,the size of the cubicγ'phase is about 370 nm,the squareness is better,the area fraction of theγ'phase is the largest,and the stress rupture life is the longest.The stress rupture fracture is characterized by ductile fracture.The carbides and micropores at the sub-grain boundary are the main crack sources to cause the stress rupture fracture of the sample.