Enhancements of thermal structure stability in Ni-base superalloy. [Inconel 718]

Journal Article · Tue Jun 15 00:00:00 EDT 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90578-G· OSTI ID:6544914

Dong, J X; Xie, X S; Zhang, S H ^[1]

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1. Univ. of Science and Technology, Beijing (China)

[gamma][double prime](bct DO[sub 22] structure) and [gamma][prime] (fcc L1[sub 2] structure) are typical strengthening phases in nickel-base superalloys. The unique strengthening effect of [gamma][double prime]-Ni[sub 3]Nb and [gamma][prime]-Ni[sub 3]Al helps Incone1718 to have wide industrial application. Because of the structure stability limitation of [gamma][double prime], the highest service temperature of IN718 is 650[degree]C. Microstructure instability of IN718 is mainly controlled by a [gamma][double prime] coarsening and plate-like [delta] phase formation. In order to improve structure stability, Cozar and Pineau published a pioneer paper on a modified alloy with a compact morphology of [gamma][double prime] and [gamma][prime], which showed higher thermal stability at age hardening test results. Recently a series of papers slightly modifying the chemical composition with variation of Al, Tk and Nb contents in IN718 has shown that a compact morphology can be obtained by appropriate heat treatments and that mechanical properties beyond 650[degree]C can be improved. However, structure stability at long time aging beyond 650[degree]C, as well as reasons to improve structure stability have scarcely been published. A detailed study in this paper was undertaken to develop a compact morphology. Cube-shaped [gamma][prime] particles were coated on their six faces with a shell of [gamma][double prime] precipitates, so a higher structure stability was created compared to separate precipitation of [gamma][double prime] and [gamma][prime] as the mixture of disk-shaped [gamma][double prime] and round [gamma][prime] particles in conventional IN 718. This investigation concentrates on the long time aging structure stability beyond 650[degree]C for fundamental understanding and explanation of such an improvement in thermal structure stability of compact morphology.

• OSTI ID: 6544914
• Journal Information: Scripta Metallurgica et Materialia; (United States), Vol. 28:12; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
INCONEL 718
MICROSTRUCTURE
CHEMICAL COMPOSITION
CRYSTAL STRUCTURE
EXPERIMENTAL DATA
HEAT RESISTING ALLOYS
HEAT TREATMENTS
MODIFICATIONS
MORPHOLOGY
NICKEL BASE ALLOYS
STABILITY
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
ALLOY-NI53CR19FE19NB5MO3
ALLOYS
ALUMINIUM ADDITIONS
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
DATA
ELECTRON MICROSCOPY
HEAT RESISTANT MATERIALS
INCONEL ALLOYS
INFORMATION
IRON ALLOYS
MATERIALS
MICROSCOPY
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NIOBIUM A
NUMERICAL DATA
TEMPERATURE RANGE
360102* - Metals & Alloys- Structure & Phase Studies