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Calculations of Energetics of Sigma Phase Formation and Thermodynamic Modelling in Fe-Ni-Cr System
Chvátalová, K. ; Houserová, Jana ; Šob, Mojmír ; Vřešťál, J.
The energy of formation of sigma phase with respect to standard reference structures of pure constituents were calculated using the combination of LMTO-ASA and FLAPW method for Ni-Fe and Ni-Cr systems. All results are based on the equilibrium lattice parameters of included structures. Calculated energies of formation of sigma phase of pure constituents were used for the thermodynamic modelling of the ternary system Fe-Ni-Cr. The calculated phase diagram agrees well with experimental data. Enthalpies of formation of sigma phase in Ni-Cr and in Ni-Fe obtained by thermodynamic modelling agree with the energy of formation calculated ab initio.
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Ab-Initio Calculated Energetics of Sigma Phase in Mo-Fe and Mo-Co Systems
Houserová, Jana ; Šob, Mojmír ; Vřešťál, J.
It is shown that first-principles electronic structure calculations may be used to estimate the energy of formation of sigma-phase in molybdenum-based systems. The calculations are performed with the help of the linear muffin-tin orbital method in the atomic sphere approximation (LMTO-ASA) and the full-potential linear augmented plane wave (FLAPW) method. The exchange-correlation energy is evaluated within the general gradient approximation (GGA).
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Nanoindentation and theoretical strength in metals and intermetallics
Šob, Mojmír ; Legut, Dominik ; Friák, Martin ; Fiala, J. ; Vitek, V. ; Hafner, J.
The present contribution gives an account of applications of quantum-mechanical (first-principles) electronic structure calculations to the problem of theoretical strength in metals and intermetallics. First, we briefly describe the way of simulating the tensile test and the electronic structure calculational method. Then we discuss the theoretical strength values in a number of elemental metals and intermetallics and compare them with available experimental data, both from measurements on whiskers and from nanoindentation experiments.
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