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Title: Potential and limitations of microanalysis SEM techniques to characterize borides in brazed Ni-based superalloys

Brazed Ni-based superalloys containing complex phases of different Boron contents remain difficult to characterize at the micrometer scale. Indeed Boron is a light element difficult to measure precisely. The state-of-the-art microanalysis systems have been tested on a single crystal MC2 based metal brazed with BNi-2 alloy to identify boride precipitates. Effort has been made to evaluate the accuracy in Boron quantitation. Energy-dispersive and wavelength-dispersive X-ray spectroscopy attached to a Scanning Electron Microscope have first been used to determine the elemental composition of Boron-free phases, and then applied to various types of borides. Results have been compared to the ones obtained using a dedicated electron probe microanalysis, considered here as the reference technique. The most accurate method to quantify Boron using EDS is definitely by composition difference. A precision of 5 at.% could be achieved with optimized data acquisition and post-processing schemes. Attempts that aimed at directly quantifying Boron with various standards using EDS or coupled EDS/WDS gave less accurate results. Ultimately, Electron Backscatter Diffraction combined with localized EDS analysis has proved invaluable in conclusively identifying micrometer sized boride precipitates; thus further improving the characterization of brazed Ni-based superalloys. - Highlights: • We attempt to accurately identify Boron-rich phases in Ni-basedmore » superalloys. • EDS, WDS, EBSD systems are tested for accurate identification of these borides. • Results are compared with those obtained by electron probe microanalysis. • Boron was measured with EDS by composition difference with a precision of 5 at. %. • Additional EBSD in phase identification mode conclusively identifies the borides.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;
  1. Laboratoire d'Étude des Microstructures et de Mécanique des Matériaux (LEM3), UMR CNRS 7239, Université de Lorraine, 57045 Metz (France)
  2. (ÉTS), Université du Québec, Montréal (Canada)
  3. (DAMAS), Université de Lorraine (France)
  4. Centre de Compétences en Microscopies Electroniques et Microsondes (CC-MEM), Institut Jean Lamour (IJL), UMR CNRS 7198, Université de Lorraine, 54011 Nancy (France)
  5. Service Commun de Microscopies Electroniques et de Microanalyses X (SCMEM), Université de Lorraine, 54506 Vandoeuvre les Nancy (France)
  6. École de Technologie Supérieure (ÉTS), Université du Québec, Montréal (Canada)
Publication Date:
OSTI Identifier:
22403520
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 94; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BACKSCATTERING; COMPARATIVE EVALUATIONS; DATA ACQUISITION; ELECTRON DIFFRACTION; ELECTRON MICROPROBE ANALYSIS; HEAT RESISTING ALLOYS; MONOCRYSTALS; MULTI-ELEMENT ANALYSIS; NICKEL BASE ALLOYS; PRECIPITATION; SCANNING ELECTRON MICROSCOPY; X-RAY SPECTROSCOPY