MD simulation of interactions of atomic displacement cascades with β-Nb precipitates in a zirconium matrix

Abstract

In this work, we investigated the effect of spherical binary precipitates and needle-shaped nanoparticles of β-Nb on the evolution of cascade processes in the Zr matrix using the method of molecular dynamics and many-body interatomic potentials. For a case of spherical precipitates, the formation of the interphase region with length of ~ 10 Å was observed. The fraction of the Zr atoms in the precipitate increased during the cascade processes. The Nb atoms, which were initially inside the precipitate, did not leave the boundaries of the interphase region after relaxation of the model crystallite. After the cascade process, the Nb atoms were detected Zr matrix at a distance of no more than 5 Å from interphase boundary. Point defects, as well as their clusters, are formed mainly near the surface of the precipitate. In a case of needle-shaped nanoparticles, a slight “blurring” of the particle boundaries with an increase in the number of niobium atoms in the near- boundary region were observed. After the atomic displacement cascade, part of the niobium atoms moved from nanoparticle into the near-boundary region. Only a few niobium atoms moved into the α-phase matrix outside the near-boundary region. No cases of significant dissolution of the nanoparticle were observed. We also observed the formation of clusters consisting of a mixture of vacancies and SIAs in the structure of the nanoparticle.