Special Issue "X-ray and neutron Line Profile Analysis of Microstructures"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Materials".

Deadline for manuscript submissions: 15 January 2020.

Special Issue Editors

Prof. Emeritus Tamás Ungár
E-Mail Website
Guest Editor
Department of Materials Physics, Eötvös Loránd University Budapest, PO Box 32, H-1518 Budapest, Hungary
at present at: School of Materials, The University of Manchester, Manchester, UK
Interests: line broadening; domain size; crystallite size; dislocations; microstrains; intergranular strains effect on line broadening; texture effect on line broadening; geometrically necessary dislocations; submicron grain size
Dr. Gábor Ribárik
E-Mail Website
Guest Editor
Department of Materials Physics, Eötvös Loránd University Budapest, PO Box 32, H-1518 Budapest, Hungary

Special Issue Information

Dear Colleagues,

X-ray and neutron line profile analysis proves to be an ever more powerful method to reveal many different quantitative aspects of microstructure properties in crystalline materials. It has become one of the most widely used complementary tools to electron microscopy for characterizing microstructures of materials. Functional properties of crystalline materials are determined by both the crystal structure and the imperfectness of crystal structure, where imperfectness comprises of a large variety of lattice defects. When the crystal lattice becomes imperfect diffraction peaks broaden and the kind and type of broadening also reveals great variety. Coherently scattering domains gives size broadening, dislocations, intergranular strains, thermal anisotropy in non-cubic crystals or misfit between matrix and second-phase particles produce strain broadening, planar defects of different kinds make peaks shift and broaden, chemical inhomogeneities on different scales produce specific peak shifts and shapes. All these effects can combine in various manners. On top of all that peaks can not only broaden but also become asymmetric. The vast variety of peak broadening, shift and shape is the topic of line profile analysis. Entanglement of the different causes in complex appearance of line profile patterns is the art of line profile analysis. All contributions are invited which can correlate diffraction patterns of imperfect crystalline materials with specific lattice defects. The method of obtaining lattice defect types and quantities from analysing diffraction patterns is very welcome. The relevance of specified lattice defects to fundamental materials properties is especially appreciated. Modeling diffraction patterns corresponding to different lattice defects is most welcome.

Prof. Emeritus Tamás Ungár
Dr. Gábor Ribárik
Guest Editors

Manuscript Submission Information

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Keywords

  • X-ray line broadening
  • neutron line broadening
  • size broadening
  • strain broadening
  • residual internal strains
  • intergranular strains
  • chemical heterogeneities
  • modeling diffraction patterns
  • texture and line profiles

Published Papers (3 papers)

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Research

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Open AccessArticle
Phase and Residual Stress Evaluation of Dual-Phase Al70Cr30N and Al80Cr20N PVD Films
Crystals 2019, 9(7), 362; https://doi.org/10.3390/cryst9070362 - 15 Jul 2019
Abstract
We investigated arc ion-plated Al70Cr30N and Al80Cr20N thin films deposited with three different bias voltages (50 V, 100 V, and 150 V) to study crystal phase stabilities, residual stresses, and mechanical properties. Commercial compositions of [...] Read more.
We investigated arc ion-plated Al70Cr30N and Al80Cr20N thin films deposited with three different bias voltages (50 V, 100 V, and 150 V) to study crystal phase stabilities, residual stresses, and mechanical properties. Commercial compositions of AlxCr100–xN coatings typically range from x = 50 to 70 where the cubic face centered crystal phase occurs. The present study focuses on films near the solubility limit of Al in the cubic Cr(Al)N lattice around 70 at.%, above which hexagonal AlN (h–AlN) starts to form in significant amounts. Residual stress values are obtained by two methods: grazing incidence diffraction with the wholepattern fitting and the conventional side inclination method (sin2Ψ method). When multiple phases are present in the film, wholepattern fitting turns out to be particularly effective and a comparison of both measurement methods will be discussed. The Al70Cr30N films consist of the cubic phase with crystallite sizes of about 70 nm for all bias voltages. Compressive stress increased with bias voltage from about 3 to almost 6 GPa and coatings become brittle. Al80Cr20N films showed a different dependence on bias voltage. Using 50 V bias voltage in deposition, the major phase is h–AlN phase with a crystallite grain size of < 30 nm and (0002) preferred orientation. With increasing bias the cubic phase is stabilized also reaching about 70 nm crystallite size. In general, the compressive residual stress was significantly lower than for Al70Cr30N films for the same bias voltages which may be a result of the presence of the hexagonal phase. Wear and scratch tests confirmed higher ductility of the Al80Cr20N variants but reduced resistance of the films in impact wear testing. Full article
(This article belongs to the Special Issue X-ray and neutron Line Profile Analysis of Microstructures)
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Open AccessArticle
In-Situ Synchrotron Profile Analysis after High-Pressure Torsion Deformation
Crystals 2019, 9(5), 232; https://doi.org/10.3390/cryst9050232 - 29 Apr 2019
Abstract
The presence of hydrostatic pressure is a general crucial characteristic of severe plastic deformation methods for reaching high strains and for introducing large quantities of lattice defects, which are necessary to establish new grain boundaries. Insights into the processes occurring during deformation and [...] Read more.
The presence of hydrostatic pressure is a general crucial characteristic of severe plastic deformation methods for reaching high strains and for introducing large quantities of lattice defects, which are necessary to establish new grain boundaries. Insights into the processes occurring during deformation and the influence of hydrostatic pressure are necessary to help better understand the SPD methods. A special experimental procedure was designed to simulate the hydrostatic pressure release: High pressure torsion (HPT)-deformed microstructure changes related to the release of hydrostatic pressure after the HPT deformation of copper and nickel were studied by freezing the sample before releasing the pressure. High-resolution in-situ X-ray diffraction of the heating process was performed using synchrotron radiation in order to apply X-ray line profile analysis to analyze the pressure release. The results on copper and nickel generally indicated the influence of hydrostatic pressure on the mobility and interaction of deformation-induced defects as well as the resulting microstructure. Full article
(This article belongs to the Special Issue X-ray and neutron Line Profile Analysis of Microstructures)
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Review

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Open AccessReview
Historical Perspective on Diffraction Line-Profile Analyses for Crystals Containing Defect Clusters
Crystals 2019, 9(5), 257; https://doi.org/10.3390/cryst9050257 - 17 May 2019
Abstract
Deviations of crystal diffraction line profiles from those predicted by the dynamical theory of diffraction for perfect crystals provide a window into the microscopic distributions of defects within non-perfect crystals. This overview provides a perspective on key theoretical, computational, and experimental developments associated [...] Read more.
Deviations of crystal diffraction line profiles from those predicted by the dynamical theory of diffraction for perfect crystals provide a window into the microscopic distributions of defects within non-perfect crystals. This overview provides a perspective on key theoretical, computational, and experimental developments associated with the analysis of diffraction line profiles for crystals containing statistical distributions of point defect clusters, e.g., dislocation loops, precipitates, and stacking fault tetrahedra. Pivotal theoretical developments beginning in the 1940s are recalled and discussed in terms of their impact on the direction of theoretical and experimental investigations of lattice defects in the 1960s, the 1970s, and beyond, as both experimental and computational capabilities advanced. The evolution of experimental measurements and analysis techniques, as stimulated by theoretical and computational progress in understanding the distortion fields surrounding defect clusters, is discussed. In particular, consideration is given to determining dislocation loop densities and separate size distributions for vacancy and interstitial type loops, and to the internal strain and size distributions for coherent precipitates. Full article
(This article belongs to the Special Issue X-ray and neutron Line Profile Analysis of Microstructures)
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