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

Journal Article · Tue Jun 15 04:00:00 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), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 28:12; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

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