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  4. Composition and Element Distribution Mapping of γ′ and γ" Phases of Inconel 718 by High-Resolution Scanning Transmission Electron Microscopy and X-ray Energy-Dispersive Spectrometry
 
research article

Composition and Element Distribution Mapping of γ′ and γ" Phases of Inconel 718 by High-Resolution Scanning Transmission Electron Microscopy and X-ray Energy-Dispersive Spectrometry

Buffat, Philippe A.  
•
Alexandrou, Ioannis
•
Czyrska-Filemonowicz, Aleksandra
February 1, 2024
Materials

The main strengthening mechanism for Inconel 718 (IN718), a Ni-based superalloy, is precipitation hardening by gamma ' and gamma '' particles. It is thus essential, for good alloy performance, that precipitates with the desired chemical composition have adequate size and dispersion. The distribution of the gamma ' and gamma '' phases and their chemical composition were investigated in the nickel-based Inconel 718 superalloy by taking advantage of the new capabilities of scanning transmission electron microscopy and energy-dispersive X-ray spectrometry using a windowless multiple detector, a high-brightness Schottky electron gun, and a spherical aberration corrector in the illumination probe optics. A small routine was developed to deconvolute the respective compositions of gamma ' and gamma '' nanoprecipitates embedded in the gamma matrix. Keeping the electron probe current low enough-a few hundred pA-prevented excessive irradiation damage during the acquisition of element maps and brought their spatial resolution down to the atomic column level to track their element compositions. The present results agree with and complement atomic probe tomography observations and Thermo-Calc predictions from the literature. The presence of an Al enrichment at the gamma '/gamma '' interface-which may control the gamma '' phase coarsening-is observed in the last row of Al-Nb-Ti columns along this interface. In addition, a few columns with similar composition changes are found randomly distributed in the gamma ' phase.

  • Details
  • Metrics
Type
research article
DOI
10.3390/ma17030594
Web of Science ID

WOS:001160289400001

Author(s)
Buffat, Philippe A.  
Alexandrou, Ioannis
Czyrska-Filemonowicz, Aleksandra
Date Issued

2024-02-01

Publisher

MDPI

Published in
Materials
Volume

17

Issue

3

Start page

594

Subjects

Physical Sciences

•

Technology

•

Superalloys

•

Inconel

•

Interface Structure

•

Phase Composition

•

Edxs-Hrstem

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LENI  
FunderGrant Number

European Union

ESTEEM2 project

FP7 contract

Available on Infoscience
March 18, 2024
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/206372
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