Evaluation of the structure and properties for the high-temperature phase of zirconium from the atomistic simulations

Abstract We study peculiarities of phase transitions in zirconium and properties of the high-temperature β -Zr phase. To get a more detailed understanding of the structure and thermodynamic characteristics of zirconium, we perform atomistic simulations with two different interatomic potentials. Both potentials demonstrate an unstable behavior of β -Zr phase at low temperatures but explain this phenomenon by substantially different reasons. For one of the potentials, the mechanical instability takes place, and for the other potential the instability of β -Zr is purely dynamic. Review of the available experimental data shows that it is more correct to describe β -Zr through the low-temperature dynamic instability. The structure peculiarity discussed for β -Zr leads to a local non-cubic symmetry of this phase and low formation energy of the self-interstitial atoms. The latter leads to fast atomic self-diffusion that is consistent with existing data. We also perform deformation tests for the atomistic models of β -Zr-Nb alloys taking into account the studied details of α - β transition.