ABSTRACT
We report electron probe microanalysis measurements on nickel silicides, Ni5Si2, Ni2Si, Ni3Si2, and NiSi, which were done in order to investigate anomalies that affect the analysis of such materials by using the Ni L3-M4,5 line (Lα). Possible sources of systematic discrepancies between experimental data and theoretical predictions of Ni L3-M4,5 k-ratios are examined, and special attention is paid to dependence of the Ni L3-M4,5 k-ratios on mass-attenuation coefficients and partial fluorescence yields. Self-absorption X-ray spectra and empirical mass-attenuation coefficients were obtained for the considered materials from X-ray emission spectra and relative X-ray intensity measurements, respectively. It is shown that calculated k-ratios with empirical mass attenuation coefficients and modified partial fluorescence yields give better agreement with experimental data, except at very low accelerating voltages. Alternatively, satisfactory agreement is also achieved by using the Ni L3-M1 line (Lâ) instead of the Ni L3-M4,5 line.
ABSTRACT
Electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA) measurements are combined to characterize an industrial produced dual-phase steel containing some bainite fraction. High-resolution carbon mappings acquired on a field emission electron microprobe are utilized to validate and improve the identification of the constituents (ferrite, martensite, and bainite) performed by EBSD using the image quality and kernel average misorientation. The combination eliminates the ambiguity between the identification of bainite and transformation-induced dislocation zones, encountered if only the kernel average misorientation is considered. The detection of carbon in high misorientation regions confirms the presence of bainite. These results are corroborated by secondary electron images after nital etching. Limitations of this combined method due to differences between the spatial resolution of EBSD and EPMA are assessed. Moreover, a quantification procedure adapted to carbon analysis is presented and used to measure the carbon concentration in martensite and bainite on a submicrometer scale. From measurements on reference materials, this method gives an accuracy of 0.02 wt% C and a precision better than 0.05 wt% C despite unavoidable effects of hydrocarbon contamination.
ABSTRACT
An open source software package dedicated to processing stored electron backscatter patterns is presented. The package gives users full control over the type and order of operations that are performed on electron backscatter diffraction (EBSD) patterns as well as the results obtained. The current version of EBSD-Image (www.ebsd-image.org) offers a flexible and structured interface to calculate various quality metrics over large datasets. It includes unique features such as practical file formats for storing diffraction patterns and analysis results, stitching of mappings with automatic reorganization of their diffraction patterns, and routines for processing data on a distributed computer grid. Implementations of the algorithms used in the software are described and benchmarked using simulated diffraction patterns. Using those simulated EBSD patterns, the detection of Kikuchi bands in EBSD-Image was found to be comparable to commercially available EBSD systems. In addition, 24 quality metrics were evaluated based on the ability to assess the level of deformation in two samples (copper and iron) deformed using 220 grit SiC grinding paper. Fourteen metrics were able to properly measure the deformation gradient of the samples.
