Overlapping of [gamma][double prime] precipitate variants in Inconel 718

Journal Article · Tue Nov 30 23:00:00 EST 1993 · Materials Characterization; (United States)

DOI:https://doi.org/10.1016/1044-5803(93)90062-Z· OSTI ID:5434720

Sundararaman, M; Mukhopadhyay, P ^[1]

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1. Bhabha Atomic Research Centre, Bombay (India)

Inconel 718 is a commercial, nickel-iron base, precipitation hardenable superalloy. Precipitation strengthening in this alloy is brought about mainly by the precipitation of a metastable, ordered, intermetallic phase, designated as [gamma][double prime] (DO[sub 22] ordered structure). This phase is based on the composition Ni[sub 3]Nb, although aluminum and titanium partially substitute for niobium. In Inconel 718 some precipitation strengthening is also derived from metastable [gamma][double prime] precipitates that have the L1[sub 2] ordered structure. Inconel 718 is used as a structural material for service at temperatures up to 973 K. The precipitation strengthening effect in this alloy is attributed mainly to the large coherency strains associated with the tetragonal distortion of the fcc matrix. The distribution of different precipitate variants affects the strength of the alloy. In systems containing disk-shaped precipitates (tetragonal distortion), regular or quasi-regular precipitate arrays are formed. These arrays are often stable, and their formation tends to inhibit particle coarsening. One such example is the apparent coating of the [gamma][double prime] phase on all faces of cuboidal [gamma][prime] particles in Inconel 718 type alloys. The coarsening behavior of [gamma][double prime] particles in Inconel 718 has been well studied. This article reports the observation of the occurrence of apparent intersection of different variants of precipitates and attempts to explain such intersections on the basis of structure factor contrast.

• OSTI ID: 5434720
• Journal Information: Materials Characterization; (United States), Journal Name: Materials Characterization; (United States) Vol. 31:4; ISSN 1044-5803; ISSN MACHEX
• 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
AUSTENITE
CARBON ADDITIONS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
ELEMENTS
HARDENING
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCONEL 718
INCONEL ALLOYS
IRON ALLOYS
MATERIALS
METALS
MOLECULAR STRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM
NIOBIUM A
PRECIPITATION HARDENING
STRUCTURAL CHEMICAL ANALYSIS
STRUCTURE FACTORS
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TRANSITION ELEMENTS