Papers by Author: Tamás Ungár

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Authors: Erhard Schafler, Ch. Sitkovitch, Iuliana C. Dragomir, Ádám Révész, Michael Zehetbauer, Tamás Ungár
Authors: Jenő Gubicza, Iuliana C. Dragomir, Gábor Ribárik, Yuntian T. Zhu, Ruslan Valiev, Tamás Ungár
Authors: Iuliana C. Dragomir, András Borbély, Tamás Ungár
Abstract: Anisotropic strain broadening of diffraction peaks can be parameterised by dislocation contrast factors. A comprehensive software has been developed and made available through the internet to determine the individual and averaged contrast factors which are also compiled for cubic and hexagonal crystals. Using the theoretical and the measured values of contrast factor the microstructure of the specimen can be characterised in terms of active slip systems, Burgers vector populations, dislocation densities and crystallite size- and size distribution.
Authors: Tamás Ungár
Abstract: X-ray diffraction line profile analysis can be carried out on the hkl planes corresponding to the same texture component or the same crystallographic orientation fiber. It is shown that in textured polycrystalline materials or in thin films or multilayers X-ray line profiles measured on planes corresponding either to the main or the minor texture components can provide the Burgers vector population and dislocations densities in the different texture components separately. The experimental technique is outlined for textured specimens and the multiple convolutional whole profile method, i.e. the CMWP line profile analysis procedure, is presented for its capacity to determine the substructure pertaining to different texture components in textured samples.
Authors: M. Liu, Hans Jørgen Roven, Tamás Ungár, L. Balogh, Maxim Yu. Murashkin, Ruslan Valiev
Abstract: An Al–0.5 Mg alloy and a commercial AA5182 alloy were subjected to high pressure torsion (HPT) to five turns under pressure of 6 GPa at room temperature. The grain boundary structure and deformation defects were investigated after HPT using high-resolution transmission electron microscopy (HRTEM). Low-angle, high-angle, equilibrium and non-equilibrium grain/subgrain boundaries, twin boundaries, full dislocations, dipoles, microtwins and stacking faults were identified by HRTEM. Extrinsic 60° dislocations in the form of dipoles were frequently observed in non-equilibrium grain/subgrain boundaries. In addition subgrain size distributions and dislocation densities were quantified by x-ray line profile analysis. It was observed that the average grain size decreased from about 120 nm to 55 nm as the Mg content increased from 0.5 to 4.1 wt%. Concomitantly the average stored dislocation density increased from 1.7 to 12.8  1014 m-2. Based on the HRTEM investigations and the x-ray line profile analyses, the deformation mechanism associated with the typical grain boundaries and deformation defects in the aluminium alloys were discussed.
Authors: R. Sedláček, S. Straub, A. Borbély, Tamás Ungár, Wolfgang Blum
Authors: Z. Somogyvári, E. Sváb, Gy. Mészáros, Kiril Krezhov, P. Konstantinov, Tamás Ungár, Jenő Gubicza
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