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

Journal Article · Fri Aug 15 00:00:00 EDT 2014 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2014.04.009· OSTI ID:22403520

Mathieu, S. ^[1]; others, and

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1. Service Commun de Microscopies Electroniques et de Microanalyses X (SCMEM), Université de Lorraine, 54506 Vandoeuvre les Nancy (France)

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-based 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.

• OSTI ID: 22403520
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 94; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

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