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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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Ab initio simulation of three-axial deformation of perfect iron crystal
Černý, M. ; Šandera, P. ; Pokluda, J. ; Friák, Martin ; Šob, Mojmír
Ab initio electronic structure calculations of ideal strength, bulk modulus and equilibrium lattice parameter of iron in the body-centered-cubic lattice under three-axial tension are performed using the linear muĆn-tin orbitals method in atomic sphere ap proximation (LMTO-ASA) and the full-potential linearized augmented plane waves method (FLAPW). Magnetic ordering was taken into account by means of spin-polarized calculation. Two exchange-correlation energy approximations were employed, namely the local (spin) den-sity approximation (LDA) and the generalized gradient approximation (GGA). Computed values are compared with experimental data.
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Ab initio simulation of a tensile test in iron
Friák, Martin ; Šob, Mojmír ; Vitek, V.
A tensile test in ferromagnetic and nonmagnetic iron is simulated by ab initio electronic structure calculations using all-electron full potential linearized augmented plane wave method (FLAPW) within generalized gradient approximation (GGA). The theoretical tensile strength of ferromagnetic iron for [001] loading is determined and compared with that of other materials. The magnetic behavior of iron under tensile loading is studied in detail and compared with results for triaxial loading.
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Properties of interfaces at nanometric scale
Lejček, Pavel ; Paidar, Václav
First let us focus on the TiAl ordered intermetallic alloys that represent due to very favourable strength-to-ratio, and thus light weight required by transport vehicles, an advanced material for the aerospace and automotive applications. The second example is closer to classical materials. The properties of polycrystals can be, at least in principle, improved by grain boundary engineering.
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Interfaces in TiAl
Paidar, Václav
Two tipes of interfaces can be distinguished in gama-phaseod TiAl ordered alloys: Special rotational interfaces on the {111} planes for which the misorientation angle with respect to the axis perpendicular to the interface plane is a multiple of 60grade. And common grain boundaries with arbitrary orientations of the boundary plane and rotation axis.
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