B. N. Grudin

Graphics processors in problems of electron tomography

Algorithms were developed for the tomographic reconstruction of structure from microscopic images using graphics processors of general application. The effect of noise and the choice of reconstruction filters for tomographic problems in materials science is investigated. It is shown that the use of ρ-filtration in reconstruction allows one to estimate the geometrical characteristics of three-dimensional microstructures in amorphous metal alloys.

Methods of Analysis of the Structure of Materials on the Basis of Orthogonal Transformations of Microscopic Images

Some methods for studying the structure of materials on the basis of microscopic images are considered. The images are analyzed using various orthogonal transformations: Fourier, cosine, Hartley, and continuous wavelet transformations.

HAADF-STEM investigation of the structures of electrolytically deposited CoP and CoNiP alloys

The structure and chemical composition of electrolytically deposited films of CoP and CoNiP amorphous alloys are studied by means of high-angle annular dark-field scanning transmission electron microscopy in the z-contrast mode, and via EELS and EDS spectroscopy with high locality. It is shown that variations in chemical composition correlate with heterogeneities in film structure.

Investigating the structure of electrolytically deposited alloys of the CoP-CoNiP system under thermal action

The problems of structural relaxation and crystallization of electrolytically deposited amorphous metal alloys of the CoP-CoNiP system are investigated. The onset of the structural relaxation and crystallization is found to occur through the nucleation of nanocrystalline particles of an unrecognized CoxNiyP1−x−y phase. An increase in the concentration of Ni is shown to yield a substantial thickening of the amorphous structure and to increase the temperature of the onset of structural relaxation and crystallization by 50–70°C.

Gibbs distribution-based Bayesian segmentation of electron microscopy nanostructure images

The use of Gibbs distribution-based Bayesian segmentation of electron microscopy images for visualizing nanostructures is investigated. Bayesian segmentation involves dividing an image into nonoverlapping areas that correspond as closely as possible to the observed image. A quantitative characteristic of this correspondence is the a posteriori probability of one variant of division or another. The most likely version is always the division with the greatest a posteriori probability. The Metropolis algorithm for stochastic relaxation is used to obtain Bayesian estimates of the a posteriori probability of a division. Our study of Bayesian segmentation requires visualization of nanostructures on an electron microscopy image of a film made of NiW nanocrystalline alloy.

Electron tomography algorithms in scanning transmission electron microscopy

Different weighting filters used in tomographic algorithms are investigated. Algorithms for the recovery of tomographic structures are produced for general application in graphic processors. Software for a Carl Zeiss Libra 200FE microscope that enables us to record a series of projections in the STEM mode is developed. Calculation experiments show the improvement in tomogram quality when using cosine and 1/z2 filters instead of a linear filter at high noise levels for objects larger than 25 points.

Electron tomography and morphological analysis of the structure of multicomponent amorphous and nanocrystalline alloys

The structure of amorphous and nanocrystalline alloys of the CoP-CoNiP and CoW-CoNiW systems is investigated by means of electron tomography. The systems’ morphometric characteristics are obtained, and the results from two-dimensional imaging and three-dimensional reconstructions are compared.

Simulation and analysis of images using spectral characteristics

Methods intended for the analysis and simulation of microstructure images using integral spectral characteristics of orthogonal transformations are proposed. The described methods, algorithms, and software tools allow the primary processing of such images, along with identifying the correlation spectrum characteristics of microstructures and eliminating distortions related to smearing, blurring, and defocusing.

TEM and STEM Electron Tomography Analysis of Amorphous Alloys CoP-CoNiP System

This paper covers the analysis of amorphous alloys CoP-CoNiP system by means of high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy and electron tomography. The last years have seen a sufficient progress in the analysis of nanomaterials structure with the help of high resolution tomography. This progress was motivated by the development of microscopes equipped with aberration correctors and specialized sample holders which allow reaching the tilts angles up to ±80°. The opportunities delivered by the method of electron tomography sufficiently grow when producing high resolution images and using chemical analysis, such as X-Ray energy-dispersive microanalysis and electron energy loss spectroscopy (EELS).

Analyzing the fractal properties of a structure via microscopic images

Space-frequency filtering and filters based on Fourier images of Gaussian and Morlet wavelets are used to synthesize microstructure images with fractal properties. Ways of analyzing the local fractal properties of structures, based on evaluating the fractal dimension in a small sliding window, are proposed and studied.