(中国科学院 金属研究所，沈阳 110016)
摘 要: 研究了Ti-46.5Al-2Cr-2Nb-0.15B合金铸锭不同位置的显微组织及其650 ℃持久性能。结果表明：铸锭不同部位显微组织与凝固速率有关，其中凝固速率较大的边缘形成了片层界面与铸锭轴向平行的晶粒，而凝固速率较小的芯部则形成了片层界面取向杂乱的晶粒。相应组织在相同试验条件下的持久性能差异明显，其中边缘试样持久寿命长且断后伸长率大；而芯部试样持久寿命短且断后伸长率小，这与不同方向加载应力下的两相片层变形协调性有关。
关键字: γ-TiAl基合金；铸态组织；持久性能；片层取向
（Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The microstructures of different parts of a cast Ti-46.5Al-2Cr-2Nb-0.15B ingot as well as the influence of microstructure on creep rupture properties were investigated. The results suggest that the microstructure is closely related to solidification rate, grains with lamellae parallel to the ingot’s axis are found near the edge of the ingot where solidification is fast, while grains near the inner part of the ingot have scattered lamellar orientation on account of the slower solidification rate. Different microstructures result in different creep rupture properties, specimens near the edge of the ingot exhibit better creep rupture properties including creep rupture life and elongation, while specimens near the center of the ingot have lower creep rupture life and elongation. This is due to the deformation of the two phases under different loading direction.
Key words: γ-TiAl-based alloy; cast structure; creep rupture property; lamellar orientation
