摘要
采用螺旋选晶法，制备了一种镍基单晶高温合金。在非真空箱式电阻炉中进行分级均匀化热处理，研究了热处理制度对合金显微组织及持久性能的影响。结果表明：合金的铸态组织由γ-Ni固溶体相、初生和次生的γ＇-Ni3Al相、以及γ／γ＇共晶相组成；1305-1310℃、16h固溶处理后，次生γ全部固溶，少量γ／γ＇共晶没有完全固溶；1315℃、16h固溶处理后，γ／γ＇共晶全部固溶；1320℃、2h固溶处理后，出现少量初熔；两次时效处理明显改变了γ的尺寸、形貌及分布；合金经1180℃、2 h＋1290℃、2 h＋1315℃、16h AC＋1140℃、4 h AC＋870℃、24h AC完全热处理后，在1100 ℃，137MPa条件下持久寿命达到100h。持久裂纹主要沿与拉应力垂直的枝晶间横向段萌生扩展，与γ／γ＇共晶完全固溶状态相比，未固溶的γ／γ＇共晶更容易成为主要裂纹源。
A Ni-base single crystal superalloy was prepared by screw selecting method. The homogenizing heat treatment carried out in an antivacuum chamber oven, and the effect of heat treatment on the microstructure and stress rupture life at 1 100℃ was studied. The results show that the as-cast structure of the alloy is composed of γ- Ni solid solution phase, primary and secondary γ＇-Ni3 Al phase, and γ/γ＇ phases. After solid solution treatment under the condition of 1 305 - 1 310℃ for 16 h, secondary γ is solved completely but a small amount of γ/γ＇ eutectic remains. While after the solid solution treatment at 1 315℃ for 16 h, γ/γ＇ eutectic is solved completely. A small amount of primary melting appears after the solid solution treatment at 1 320℃ for 2 h. It is found that the sizes, morphologies and distributions of γ phase change greatly by double aging treatment. After full heat treatment of 1 180℃, 2 h＋1 290℃, 2 h＋1 315 ℃, 16 h AC＋1 140 ℃, 4 h AC＋870 ℃, 24 h AC, the stress rupture life of alloy is 100 h under the condition of 1 100 ℃ and 137 MPa. The study of the microstructure for cracked specimens shows that the cracks propagate mainly along the interdentritic area perpendicular to the tensile stress. It is also found that the remained γ/γ＇ eutectic is the weak and crack initiation points during the creep tests of the alloy.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2006年第6期937-944,共8页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(50371004)
关键词
镍基单晶高温合金
固溶处理
热处理
持久性能
显微组织
Ni-base single crystal superalloy
solid solution treatment
heat treatment
stress rupture properties
microstructure
