The curriculum concentrates on the comprehensive study of materials properties and failure processes from the point of view of physics and physical metallurgy. Students should develop capability to apply their knowledge in inventive manner to new technologies and materials, such as plasma spraying, special methods of thermo-mechanical and thermo-chemical treatment, etc. Special attention is paid to the degradation processes and to the synergetic effects of various materials properties on material failure. The subjects of study are metallic and non-metallic materials, e.g., structural ceramics, polymers, amorphous and nanocrystalline materials and intermetallics.
The Ph.D. programme requires proficiency in mathematics and physics at the MSc. degree level obtained from Faculty of Science or Faculty of Mechanical Engineering.

prof. RNDr. Petr Dub, CSc.

1. Mechanical properties and strengthening mechanisms in complex alloys

   Complex alloys containing elements in equimolar ratio belongs to perspective group of advanced materials with extremely good combination of strength and deformation properties, with potential to improved corrosion resistance and other application properties. Excellent mechanical properties are result of combination of strengthening and toughening micromechanisms, in particular nanotwinning and deformation induced plasticity due phase transformations. PhD project will be focused on design of these alloys based on theoretical knowledge supported by semiempirical findings from similar systems. Selected compositions will be experimentally prepared by casting and powder metallurgy route. Then, relationship between microstructure, fabrication procedures and final mechanical properties will be investigated. Special interest will be focused on characterisation and quantification of deformation mechanisms and phase compositions by advanced electron microscopy methods. As a result new complex alloys with optimised preparation procedures, known performance during mechanical loading and key application properties.

   Tutor: Dlouhý Ivo, prof. Ing., CSc.

2. Mechanism of the small creep strains of the metallic materials at low stresses and transition to the plastic strain

   Creep strains measured at very low applied stresses are by their properties very different from those measured at higher stresses with the conventional creep tests [1]. The stress and strain dependencies of the creep rate are much weaker and the strain is mostly anelastic. The deformation mechanism of these strains is not known, mainly because there are no observable traces of the process in the microstructure due to their very small extent. The strain is clearly connected to the internal stresses field building. There is only one simplified micromechanical model based on the dislocation segments bowing, combining the viscous glide and climb of dislocations [2], but it is only capable to describe very small strains not explaining the transition to normal plastic creep strains. Development of the complex dislocation model of the creep strain of the metallic materials at very low stresses including transition to plastic creep strain is the main topic of the thesis. The solution will be based on the simplified model mentioned above and will include realistic description of the interactions between dislocation and segregated cloud of the solute atoms, discrete dislocation dynamics method and statistical description of the fraction of the dislocation segments reaching the critical stress. Experimental study of the low-stress creep of the selected metalic materials will be important part of the work. The materials having exceptional creep behaviour observed with the conventional creep tests will be prefered. The work will be hosted mainly in the Institute of Physics of materials AS CR [http://www.ipm.cz], where all the necessary equipment is available. Literature [1] Kloc L.: Acta Physica Polonica A128 (2015), 540. Doi: 10.12693/APhysPolA.128.540 [2] Kloc L.: in: K. Maruyama et al. (eds.), Creep and fracture of engineering materials and structures, Kyoto, The Japan institute of Metals (2012), B28.

   Tutor: Kloc Luboš, RNDr., CSc.

3. Theoretical modeling of phase stability and mechanical properties of alloys based on transition metals

   At the present time, theoretical methods for electronic-structure calculations based on ab initio approach are recognize as well established scientific tool. They can be used also for design of new materials and prediction of their application properties. Because these methods are based purely on elemental laws of quantum mechanics, they do not need any impute experimental data. This is very useful for prediction of properties for such materials, which can be prepared experimentally only with difficulties or with high cost. The aim of this work is to apply ab initio methods for prediction of phase stability and mechanical properties of perspective materials such as magnetic shape memory alloys and high entropy alloys based on transition metals. The PAW method implemented in simulation package VASP will be employed for this work. The results will be used as inputs to Peierls-Nabarro model for dislocation motion.

   Tutor: Zelený Martin, Ing., Ph.D.