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Inter‐ and intragranular delta phase quantitative characterization in Inconel 718 by means of image analysis
Author(s) -
VANDERESSE N.,
ANDERSON M.,
BRIDIER F.,
BOCHER P.
Publication year - 2016
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/jmi.12317
Subject(s) - inconel , materials science , characterization (materials science) , phase (matter) , superalloy , brightness , microstructure , orientation (vector space) , image (mathematics) , biological system , computer science , artificial intelligence , optics , metallurgy , nanotechnology , chemistry , physics , geometry , mathematics , alloy , biology , organic chemistry
Summary This paper describes an image processing method for discriminating the inter‐ and intragranular delta phase precipitates in Inconel 718 (IN 718). The successive practical operations and the motivations of their choices are presented in detail. The method was applied to IN 718 specimens heat treated with different parameters to produce microstructures containing various amounts of both types of precipitates. They were characterized by electron microscopy in backscattered electron imaging. The main difficulty arose from the fact that the brightness distributions of inter‐ and intragranular precipitates partially overlap. Additional information on their morphology and their spatial distribution had to be exploited in order to differentiate them. The shape and the orientation of the precipitates were evaluated using the structure tensor, an operator that quantifies the directionality of the intensity distribution in an image. The distance between parallel precipitates was also used as an additional property to identify clusters of intragranular precipitates.