iCHORD-SI combination as an alternative to EDS-EBSD coupling for the characterization of γ-γ′ nickel-based superalloy microstructures

Journal Article · Wed Aug 15 04:00:00 EDT 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.06.015· OSTI ID:22832996

Vernier, Suzanne ^[1]; Franchet, Jean-Michel ^[2]; Lesne, Maxime ^[3]; Douillard, Thierry; Silvent, Jérémie ^[3]; Langlois, Cyril; Bozzolo, Nathalie ^[1]

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1. MINES ParisTech, PSL – Research University, CEMEF – Centre de mise en forme des matériaux, CNRS UMR7635, 1 Rue Claude Daunesse, 06904 Sophia Antipolis (France)
2. Safran SA, Safran Tech – Materials & Processes Department, Rue des Jeunes Bois - Châteaufort, 78772 Magny-les-Hameaux (France)
3. Orsay Physics – Tescan Orsay Holding, ZAC Saint-Charles, 95 Avenue des Monts Auréliens, 13710 Fuveau (France)

Highlights: • A new method to get orientation maps discriminating the gamma and gamma’ phases of Ni superalloys is described. • The method combines the iCHORD technique with secondary ion imaging. • The new method resolves precipitates down to 150 nm within a reasonable acquisition time. - Abstract: Because they exhibit very similar diffraction patterns, the γ and γ′ phases of nickel-based superalloys cannot be distinguished by the conventional EBSD technique alone. This paper presents an original method which discriminates those phases on an orientation map by exploiting their chemical differences. Performed with a Focused Ion Beam (FIB) microscope, the method is the combination of the ion CHanneling ORientation Determination technique (iCHORD) – recently developed by Langlois et al. [1] – with the chemical information obtained from Secondary Ion (SI) images. The performances of the method are compared to the EDS-EBSD coupling which also discriminates phases based on their chemical compositions. Applied filters, angular resolution, spatial resolution of the phase discrimination and acquisition time are discussed. It results that the iCHORD–SI combination offers an orientation map with an angular resolution slightly decreased compared to that of the EBSD technique, but with a good phase resolution (down to 150 nm) and within a reasonable acquisition time. Thus, the iCHORD–SI combination appears to be an interesting method for the crystallographic systems where phases are difficult to discriminate by the EBSD technique alone but present a significant chemical contrast.

• OSTI ID: 22832996
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 142; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BACKSCATTERING
COMPARATIVE EVALUATIONS
CRYSTALLOGRAPHY
ELECTRON DIFFRACTION
HEAT RESISTING ALLOYS
ION BEAMS
ION CHANNELING
MICROSCOPES
MICROSTRUCTURE
NICKEL ALLOYS
PRECIPITATION
SPATIAL RESOLUTION