摘要
定向凝固高温合金DZ125在航空发动机上广泛用作涡轮叶片,本工作研究微量元素P对DZ125合金微观组织、力学性能和裂纹倾向性的影响。结果表明:P元素在DZ125合金中主要偏聚在晶界处,对合金中γ′、γ+γ′共晶、碳化物等影响很小。当P含量达到0.008%(质量分数,下同)时,铸态合金在枝晶间形成了富P相,热处理后富P相回溶消失;当P含量不超过0.0039%时,P对DZ125合金的室温拉伸性能及980℃/235MPa持久寿命没有明显影响,但对760℃/805 MPa持久寿命有明显影响,P含量为0.0039%的合金760℃/805MPa持久寿命相较于P含量为0.0013%的合金下降了37%,这是由于较高含量的P元素在晶界偏聚导致晶界弱化所致。当P含量达到0.011%时,DZ125合金空心涡轮叶片在定向凝固过程中出现了明显的沿晶裂纹。DZ125合金裂纹倾向性增加的主要原因是过量的P在晶界富集,并析出富P相,导致晶界弱化和裂纹萌生。
The directionally solidified superalloy DZ125 is widely used as turbine blades in aero-engines.This work investigates the influence of phosphorus(P)on the microstructure,mechanical properties and crack susceptibility of DZ125 alloy.The results indicate that P primarily segregates at grain boundaries in DZ125 alloy and has little effect onγ′phases,γ+γ′eutectic and carbides in the alloy.When P content reaches 0.008%(mass fraction,the same below)P-rich phases form in the interdendritic regions during casting,which subsequently dissolve back into the matrix during heat treatment.When the P content is no more than 0.0039%,P shows no obvious effects on the room-temperature tensile properties or the stress rupture life at 980℃/235 MPa.However,it has a significant impact on the stress rupture life at 760℃/805 MPa:the alloy with 0.0039%P exhibits a 37%decrease in stress rupture life at 760℃/805 MPa compared to the alloy with 0.0013%P,due to the segregation of P at grain boundaries weakens the grain boundaries.When the P content reaches 0.011%,the intergranular cracks appear in the DZ125 alloy hollow turbine blades during directionally solidified process.The main reason for the increase of crack susceptibility is excessive enrichment of P at grain boundaries and precipitation of P-rich phases nearby grain boundaries,which leads to grain boundary weakening and crack initiation.
作者
宋尽霞
姜驰航
康永旺
肖程波
蒋立武
李明
戴圣龙
SONG Jinxia;JIANG Chihang;KANG Yongwang;XIAO Chengbo;JIANG Liwu;LI Ming;DAI Shenglong(Science and Technology on Advanced High Temperature Structural Materials Laboratory,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;National Center for Materials Service Safety,University of Science and Technology Beijing,Beijing 100083,China)
出处
《航空材料学报》
北大核心
2025年第5期142-149,共8页
Journal of Aeronautical Materials
基金
国家重点研发计划项目(2022YFB3705004)。
