Ti-Al-Zr-Mo-Nb-Sn-Si系铸造钛合金高温蠕变性能及显微组织研究

针对Ti-Al-Zr-Mo-Nb-Sn-Si铸造高温钛合金,研究了其在600℃、750℃下的蠕变性能与组织变化。结果显示,该铸造钛合金在750℃/180 MPa/0.5 h和600℃/400 MPa/0.5 h条件下的蠕变残余伸长率分别<3%和<0.4%,持久断裂时间分别为>2 h和14 h,具有良好的蠕变性能;高温蠕变断口存在细小颗粒;高温蠕变后塑性变形区的组织变化较小,呈魏氏组织,而集中变形区存在部分晶界消失、α片层宽化现象;高温蠕变后位错明显增多,与析出相相互纠缠。 

High Temperature Creep Properties and Microstructure of Ti-Al-Zr-Mo-Nb-Sn-Si Cast Titanium Alloy

The creep properties and microstructures of Ti-Al-Zr-Mo-Nb-Sn-Si cast titanium alloy at 600~750 ℃ were studied. The results showed that the creep residual elongations were less than 3% at 750 ℃/180 MPa/0.5 h and less than 0.4% at 600 ℃/400 MPa/0.5 h. The time before creep ruptures were more than 2 h and more than 14 h, respectively. The cast titanium aiioy had good creep resistance. There were fine particles in the high temperature creep fracture surface. After creep, the microstructure changed little in the plastic deformation zone, showing widmannstatten structure, and some grain boundaries disappeared and α lamellae became wider. After high temperature creep, dislocations increased obviously and entangled with precipitates.