Abstract:
The purpose of this work is to investigate the behavior of stable one-component delocalized nonlinear vibrational modes in simple cubic titanium and nickel sublattices, as well as their influence on the properties of the binary NiTi alloy. Methods. All calculations were performed using the molecular dynamics method with many-body interatomic potentials. Results. Seventeen vibrational modes are shown to exhibit stable periodic oscillations. Most of them demonstrate a hard type of nonlinearity, where the frequency of atomic vibrations increases with amplitude. Stable modes are capable of accumulating energy in the range of 0.1–1.5 eV per atom in the titanium sublattice and 0.1–1.0 eV per atom in the nickel sublattice. Excitation of vibrational modes in the Ni and Ti sublattices leads to a decrease in specific heat for modes with hard type of nonlinearity and to an increase for modes with soft type of nonlinearity. The presence of modes leads to the emergence of positive compressive stresses, the magnitude of which is proportional to the atomic displacement vector. Conclusion. The obtained results provide new insights into the complex behavior of vibrational modes and their impact on the properties of the binary NiTi alloy.
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