Modern materials

Ultra fine grained and nanocrystalline materials belong to an important group of modern materials with unusual properties that are very attractive for different structural and functional applications. Modern techniques of preparation of these materials are based on the imposition of very high strains leading to exceptional grain refinement without any significant change of the overall dimensions. High hydrostatic pressures are applied during these processes which introduce high densities of lattice defects (e.g. dislocations or vacancies) and result in the formation of special structures. Materials fabricated by these techniques, called severe plastic deformation, exhibit several unique properties including very high strength, ductility and fatigue endurance, increased superplastic capabilities as well as multifunctional behaviour when materials exhibit enhanced functional (electric, magnetic, corrosion, etc.) and mechanical properties.

For several years we have been dealing with structure investigations of various types of nanostructures (semiconductor quantum wires dots, metallic nanoparticles, etc.) using x-ray based methods such as x-ray diffraction, small-angle x-ray scattering and x-ray absorption spectroscopy. Several years ago we have started a study of the structure of new materials, like antiferromagnetic semiconductor layers and topological insulators. We perform the experiments in the x ray lab of the Department of Condensed Matter physics. Moreover, we are frequently using various synchrotron and neutron sources – ESRF and ILL (Grenoble), ANKA (Karlsruhe), ELETTRA (Trieste), APT (Argonne Nat. Lab.), PSI (Villingen), etc.

Selected outputs

• M. Janeček, J. Stráský, J. Čížek, P. Harcuba, K. Václavová, V.V. Polyakova, I.P. Semenova: Mechanical properties and dislocation structure evolution in Ti6Al7Nb alloy processed by high pressure torsion. Met. Mat. Trans. A 45, 7-15 (2014).

• J. Šmilauerová, P. Harcuba, J. Stráský, J. Stráská, M. Janeček, J. Pospíšil, R. Kužel, T. Brunátová, V. Holý, and J. Ilavský: Ordered array of omega particles in beta-Ti matrix studied by small-angle X-ray scattering. Acta Mater. 81, 71-82 (2014).

• J. Růžička, O. Caha, V. Holý, H. Steiner, V. Volobuiev, A. Ney, G. Bauer, T. Duchoň, K. Veltruská, I. Khalakhan, V. Matolín, E. F. Schwier, H. Iwasawa, K. Shimada, and G. Springholz: Structural and electronic properties of manganese-doped Bi2Te3 epitaxial layers. New J. Phys. 17, 013028 (2015).

• J. Čížek, M. Janeček, T. Krajňák, J. Stráská, P. Hruška, J. Gubicza, H.S. Kim: Structural characterization of ultrafine-grained interstitial-free steel prepared by severe plastic deformation, Acta Materialia 105 (2016), 258-272

• T. Krajňák, P. Minárik, J. Gubicza, K. Máthis, R. Kužel, M. Janeček: Influence of equal channel angular pressing routes on texture, microsctructure and mechanical properties of extruded AX41 magnesium alloy, Materials Characterization 123 (2017), 282-293

• P. Strunz, J. Šmilauerová, M. Janeček, J. Stráský, P. Harcuba, J. Pospíšil, J. Veselý, P. Lindner, L. Karge: Evaluation of anisotropic small-angle neutron scattering data from metastable β-Ti alloy, Phil. Mag. 98 (2018), 3086-3108.

• G. Springholz, S. Wimmer, H. Groiss, M. Albu, F. Hofer, O. Caha, D. Kriegner, J. Stangl, G. Bauer, V. Holý, Structural disorder of natural BimSen superlattices grown by molecular beam epitaxy, Phys. Rev. Materials 2, 054202 (2018)