Chao YUAN
,
Jianting GUO and Shuhe WANG(Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)Hongcai YANG(Dept. of Materials Science and Engineering
,
Northeastern University
,
Shenyang 110006
,
China)
材料科学技术（英）
The tensile creep-fracture properties of DZ17G. a directionally solidified superalloy, were inves-tigated at 830~ 900℃. The results show that all of the creep curves exhibit negligible primary creep, relatively little steady-state creep and dominant tertiary creep stage. The higher apparent activation energy for creep (540 kJ/mol ) suggests that the creep is controlled by Orowan bowing process. A large ratio of the fracture time to the onset time of tertiary creep is the consequence of microstructure change, i.e., γ particles oriented coarsening parallel to the applied stress axis.The creep fracture data follow the Monkman-Grant relationship. The transgranuIar fracture mechanism proposed on the basis of the metallographic examinations is the linkage of the creep cracks which initiate at the discontinuities with the microstructure (such as the cast porosity,and the carbide/matrix intedece) and also at the specimen surface, that propagate along the γ/γ intedece with perpendicular to the applied stress axis, and the process of crack propagation can be described by the Tien model.
关键词:
Chao YUAN
,
Fengshi YIN
,
Xiaofeng SUN
,
Hengrong GUAN
,
Zhuangqi HU
材料科学技术（英）
Effect of phosphorus on the microstructure and high temperature properties of a cast Ni-base superalloy M963 has been investigated. SEM observation and EDS analysis showed that P was mostly enriched in the interdendritic region, and the P-rich phase was formed in the front position of finally solidified eutectics in high P doped alloys. It was found that the P-rich phase, as preferred initiation and propagation site of cracks, could aggravate the fracture process at high temperature in high P doped alloys.Consequently, high P addition would reduce remarkably the ductility and creep life of M963 superalloy at high temperature.
关键词:
Phosphorus
,
null
,
null
,
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