Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen
OPUS4-32545 Wissenschaftlicher Artikel Nolze, Gert Euler angles and crystal symmetry For the description of (single) crystal orientations, e.g. as measured by electron backscatter diffraction (EBSD) & X-ray diffraction (XRD), Euler angles are still generally used to import and export data. However, because of the lack of standard definitions for the unit cell reference settings and specimen axes, several transformation descriptions exist which produce different sets of Euler angles for the same orientation. There is also no recommended region within the minimal Euler orientation space into which orientations should be placed. This is the reason why different sets of Euler angles for the same orientation are generated by the available software packages for indexing EBSD patterns. These issues are reviewed and addressed. The influence of crystal symmetry in form of chiral (enantiomorphic) groups is discussed, as well as how multiple, but symmetry-equivalent sets of Euler angles can be reduced in order to deliver a unique orientation description. The Euler coloring algorithms applied to EBSD map data is critically discussed. The specific case of cubic symmetry, especially the effect of the three-fold rotation on the Euler space is investigated in more detail for the highest-symmetric chiral group 432. Recommendations for standard settings of the unit cell to orthogonal coordinate system transformation are given which exploit inherent symmetry. Weinheim Wiley-VCH Verlag GmbH & Co. KGaA 13 Crystal research and technology 50 2 188 201 10.1002/crat.201400427 5 Werkstofftechnik
OPUS4-34477 Wissenschaftlicher Artikel Nolze, Gert; Grosse, C.; Winkelmann, Aimo Kikuchi pattern analysis of noncentrosymmetric crystals Different models of Kikuchi pattern formation are compared with respect to their applicability to noncentrosymmetric crystals, and the breakdown of Friedel's rule in experimental electron backscatter diffraction (EBSD) patterns is discussed. Different AIIIBV semiconductor materials are used to evaluate the resulting asymmetry of Kikuchi band profiles for polar lattice planes. By comparison with the characteristic etch pit morphology on a single-crystal surface, the polar character of the measured lattice planes can be assigned absolutely. The presented approach enables point-group-resolved orientation mapping, which goes beyond the commonly applied Laue group analysis in EBSD. Oxford Blackwell 14 Journal of applied crystallography 48 1405 1419 10.1107/S1600576715014016 5 Werkstofftechnik
OPUS4-34474 Wissenschaftlicher Artikel Petrushin, N.; Hvatzkiy, K.; Gerasimov, V.; Link, T.; Epishin, A.; Nolze, Gert; Gerstein, G. A single-crystal co-base superalloy strengthened by gamma' precipitates: structure and mechanical properties An experimental Co-base superalloy was designed from the Ni-base system by exchange of Ni and Co concentrations. The alloy consist of a Co-matrix (γ phase) strengthened by cuboidal precipitates Co3(Al,X) (γ' phase). The γ'-solvus temperature is 1?005?°C. [001] single crystals of this alloy were solidified and tested for tension at different temperatures up to 1?000?°C. It was found that the Co-base alloy has a much lower yield stress than a corresponding Ni-base alloy, but a much higher ductility. The partitioning behaviour of the alloying elements in the Co-base alloy and the deformation mechanisms were investigated by scanning and transmission electron microscopy. Weinheim Wiley-VCH Verl. 5 Advanced engineering materials 17 6 755 760 10.1002/adem.201500088 5 Werkstofftechnik
OPUS4-37787 Wissenschaftlicher Artikel Vos, M.; Winkelmann, Aimo; Nolze, Gert Element-specific Kikuchi patterns of Rutile The kinetic energy of keV electrons backscattered from a rutile (TiO2) surface depends measurably on the mass of the scattering atom. This makes it possible to determine separately the angular distribution of electrons backscattered elastically from either Ti or O. Diffraction effects of these backscattered electrons inside the rutile crystal lead to the formation of Kikuchi patterns. The element-resolved Kikuchi patterns of Ti and O differ characteristically, but each can be described fairly well in terms of the dynamical theory of diffraction. Qualitatively, much of the differences can be understood by considering the relative arrangement of the Ti and O atoms with respect to planes defined by the crystal lattice. 8 Ultramicroscopy 156 50 58 10.1016/j.ultramic.2015.04.018 5 Werkstofftechnik
OPUS4-31384 Wissenschaftlicher Artikel Winkelmann, Aimo; Nolze, Gert Chirality determination of quartz crystals using electron backscatter diffraction We demonstrate the determination of crystal chirality using electron backscatter diffraction (EBSD) in the scanning electron microscope. The chirality of a-quartz as a space-group-dependent property is verified via direct comparison of experimental diffraction features to simulations using the dynamical theory of electron diffraction. New York, NY Elsevier 5 Ultramicroscopy 149 58 63 10.1016/j.ultramic.2014.11.013 5 Werkstofftechnik
OPUS4-32670 Wissenschaftlicher Artikel Winkelmann, Aimo; Nolze, Gert Point-group sensitive orientation mapping of non-centrosymmetric crystals We demonstrate polarity-sensitive orientation mapping of non-centrosymmetric phases by Electron Backscatter Diffraction (EBSD). The method overcomes the restrictions of kinematic orientation determination by EBSD, which is limited to the centro-symmetric Laue-groups according to Friedel's rule. Using polycrystalline GaP as an example, we apply a quantitative pattern matching approach based on simulations using the dynamical theory of electron diffraction. This procedure results in a distinct assignment of the local orientation according to the non-centrosymmetric point group of the crystal structure under investigation. Melville, NY American Institute of Physics NaN Applied physics letters 106 072101-1 072101-4 10.1063/1.4907938 5 Werkstofftechnik