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

Suzanne Vernier (1) , Jean-Michel Franchet (2) , Maxime Lesne (3) , Thierry Douillard (4, 5) , Jeremie Silvent (3) , Cyril Langlois (4) , Nathalie Bozzolo (1)

1 CEMEF - Centre de Mise en Forme des Matériaux
2 Safran Tech
3 ZAC Saint Charles - Orsay Physics
4 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
5 CLYM - Consortium Lyon Saint-Etienne de Microscopie

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 an interesting 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 but present a significant chemical contrast.

Mots clés: Ion channeling; EDS-EBSD coupling; Gamma -Gamma Prime nickel-based superalloy; Focused Ion Beam; Secondary ions

Domaines: Sciences de l'ingénieur [physics]; Matériaux

Suzanne Vernier, Jean-Michel Franchet, Maxime Lesne, Thierry Douillard, Jeremie Silvent, et al.. iCHORD-SI combination as an alternative to EDS-EBSD coupling for the characterization of γ-γ′ nickel-based superalloy microstructures. Materials Characterization, 2018, 142, pp.492 - 503. ⟨10.1016/j.matchar.2018.06.015⟩. ⟨hal-01822412⟩