Creep property and microstructure evolution of a nickel-base single crystal superalloy in [011] orientation

Journal Article · Sun Dec 15 04:00:00 EST 2013 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2013.09.019· OSTI ID:22288700

Yu, J. J.; Hu, Z. Q.; Sun, X. F.

The creep property and microstructure evolution of a single crystal superalloy with [011] orientation were investigated at the temperatures of 700 °C, 900 °C and 1040 °C. It is shown that there exist stages of primary, steady-state, and tertiary creep under the lower temperature 700 °C. As the temperature increases to high temperatures of 900 °C and 1040 °C, steady-state creep stage is reduced or disappears and the shape of creep curves is dominated by an extensive tertiary stage. The minimum creep strain rate exhibits power law dependence on the applied stress; the stress exponents at 700 °C, 900 °C and 1040 °C are 28, 13 and 6.5, respectively. Microstructure observation shows that the morphologies of γ′ phase almost keep original shape at the lower temperature 700 °C and high applied stress. With the increasing creep temperature, γ′ precipitates tend to link together and form lamellar structure at an angle of 45° inclined to the applied stress. Transmission electron microscopy (TEM) investigations reveal that multiple < 110 > (111) slip systems gliding in the matrix channels and shearing γ′ precipitates by stacking faults or bending dislocation pairs are the main deformation mechanism at the lower temperature of 700 °C. At the high temperatures of 900 °C and 1040 °C, dislocation networks are formed at γ/γ′ interfaces and the γ′ rafts are sheared by dislocation pairs. - Highlights: • Creep properties of < 011 >-oriented single crystal superalloys were investigated. • γ′ phases become rafting at an angle of 45° inclined to the applied stress. • Creep deformation mechanisms depend on temperature and stress.

• OSTI ID: 22288700
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 86; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BENDING
CREEP
DISLOCATIONS
HEAT RESISTING ALLOYS
MICROSTRUCTURE
MONOCRYSTALS
NICKEL
PRECIPITATION
STACKING FAULTS
STRAIN RATE
STRESSES
TRANSMISSION ELECTRON MICROSCOPY