Metals

Nonadiabatic transitions of atoms and the formation of new phase nuclei in solids

Yu. A. Khon

Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, Tomsk

Abstract: A mechanism for the formation of nuclei of a new phase in a solid is proposed, determined by nonadiabatic Landau–Zener transitions in an open system of nuclei and electrons. Based on the analysis of the equations of nonadiabatic molecular dynamics, two order parameters are identified. The dynamics of the nucleation and growth of the embryo is determined by two related nonlinear parabolic equations for order parameters. The conditions for the formation of stable and unstable embryos are found. It is shown that the formation of the embryo can proceed in an auto-oscillatory mode. The influence of the heating (cooling) rate on the formation of new phase nuclei is considered.

Keywords: phase transformations, non-adiabatic dynamics of atoms, dynamic displacements, localization of displacements.

Received: 05.06.2023
Revised: 28.06.2023
Accepted: 29.06.2023

DOI: 10.21883/FTT.2023.08.56142.100

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