Determination of Local Strains in a Neighborhood of Cracks in a Welded Seam of Ni-Cr-Fe According to the Power Fourier Spectrum of Kikuchi Patterns

Abstract

A discrete two-dimensional Fourier transform and the power Fourier spectrum are used for determination of average strains near cracks in a welded seam of Ni-Cr-Fe alloy. The alignment of Kikuchi images with the help of genetic algorithms and subtraction of white Gaussian noise made it possible to more fully take into account the influence of instrumental factors on the formation of electron backscatter diffraction patterns.

Features of structural changes in mosaic Ge:Sb according to X-ray diffractometry and electron backscatter diffraction data

“…4) in the ε T , ε A and ε S values can be explained by different approaches to their definition. The value ε S is more influenced by anisotropy in the distribution of deformations, since it is associated not only with changes in the geometry of the bands as well as with their crystallographic orientation [24]. In our case, ε S values shows that the Kikuchi band profiles are the least blurred in regions No 1 and No 4 and close in their shape to the same ones from the etalon region (E).…”

“…The diffraction patterns pass several stages of digital processing to exclude such an influence. In particular, the comparison of the Kikuchi images No 1 -No 7 with the etalon image (E) was performed using the genetic algorithms [20,23,24]. Since the degree of blurring of the Kikuchi patterns obtained from different regions of the crystal varies significantly, it was expedient to analyze the Kikuchi patterns using the methods of two-dimensional Fourier transform and the Fourier energy spectrum [20].…”

“…Crystal deformations ∆d /d (Fig. 4) (relative changes of interplanar distances) can be determined analyzing the area changes under the Kikuchi band intensity profile ε S , and on the basis of radial distributions P R of Kikuchi image energy spectra [20,24]. Deformations ε T and ε A are found through the changes of average radial period r T (3) and the radial distribution area S PR (4) of the radial distribution P R , respectively:…”

Local distribution of strains in synthetic diamond crystals determined by the energy spectrum normalized parameters

“…Therefore, an important parameter of diamond crystals that should be taken into account is their deformations ε, which are calculated due to the change in the interplanar distance Δd/d. Among the methods for calculating the deformations of crystals, methods based on the analysis of Kikuchi patterns are especially promising, due to their high locality and non-destructive nature of research [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . In particular, crystal deformations are determined based on an analysis of the shape of intensity bands profiles and on the basis of an analysis of the Fourier energy spectrum of the Kikuchi patterns.…”

“…The presented methods for analyzing Kikuchi bands profiles involve a comparison of the areas of bands profiles obtained from different regions of the same crystal with the profile area obtained from a reference (undeformed) region of the crystal 12,13 . In case of analyzing the parameters of the energy spectrum of Kikuchi patterns, the existing methods also use one region of the crystal as a reference, and deformations in other regions are calculated in relation to it [14][15][16][17] . However, the selection of an undeformed part of the crystal is difficult or impossible in many cases, which greatly complicates the comparison of deformations calculated for different crystals.…”