Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报(英文版)

Transactions of Nonferrous Metals Society of China

Vol. 24    No. 8    August 2014

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Creep properties and microstructure evolution of nickel-based single crystal superalloy at different conditions
Zhen-xue SHI, Jia-rong LI, Shi-zhong LIU, Xiao-guang WANG

Science and Technology on Advanced High Temperature Structural Materials Laboratory,
Beijing Institute of Aeronautical Materials, Beijing 100095, China

Abstract:The creep properties of nickel-based single crystal superalloy with [001] orientation was investigated at different test conditions. The microstructure evolution of γ′ phase, TCP phase and dislocation characteristic after creep rupture was studied by SEM and TEM. The results show that the alloy has excellent creep properties. Two different types of creep behavior can be shown in the creep curves. The primary creep is characterized by the high amplitude at test conditions of (760 °C, 600 MPa) and (850 °C, 550 MPa) and the primary creep strain is limited at (980 °C, 250 MPa), (1100 °C, 140 MPa) and (1120 °C, 120 MPa). A little change of γ′ precipitate morphology occurs at (760 °C, 600 MPa). The lateral merging of the γ′ precipitate has already begun at (850 °C, 550 MPa). The γ phase is surrounded by the γ′ phase at (980 °C, 250 MPa). The γ phase is no longer continuous tested at (1070 °C, 140 MPa). At (1100 °C, 120 MPa), the thickness of γ phase continues to increase. No TCP phase precipitates in the specimens at (760 °C, 600 MPa), (850 °C, 550 MPa) and (980 °C, 250 MPa). Needle shaped TCP phase precipitates in the specimens tested at (1070 °C, 140 MPa) and (1100 °C, 120 MPa). The dislocation shear mechanism including stacking fault formation is operative at lower temperature and high stress. The dislocation by-passing mechanism occurs to form networks at γ/γ′ interface under the condition of high temperature and lower stress.

 

Key words: single crystal superalloy; creep properties; microstructure evolution; γ′ phase; TCP phase

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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