Effects of surface energy anisotropy on void evolution during irradiation: A phase-field model

Abstract

A phase-field model is employed to investigate the effects of surface energy anisotropy on void evolution during irradiation. By incorporating a simple orientation dependent surface energy with sharp cusps on given crystallographic orientations, experimentally observed void shape with facets and rounded corners is captured. When applied to polycrystalline materials, grain dependent void morphologies are predicted, and the simulation results are qualitatively similar to reported void morphologies in irradiated copper. In addition, the formation of void denuded zones and vacancy depleted zones adjacent to the grain boundaries (GBs) in bicrystalline and polycrystalline structures are studied.

Effect of Crystal Orientation on Self-Assembly Nanocones Formed on Tungsten Surface Induced by Helium Ion Irradiation and Annealing

“…Simultaneously, vacancies and interstitials of helium atoms will combine to form complex structures such as He x V y , for example He 2 V, He 3 V, He 4 V 2 (V is short for vacancy) [33,34]. Some studies show that He bubbles are preferentially trapped at the grain boundaries and interfaces during the irradiation and then annealing [22,35,36]. Therefore, the complex structures He x V y will form at the small interfaces between the nucleated new compound and tungsten matrix, which increases the defect density near the sample surface.…”

“…Parish [21] reported various surface morphologies such as smooth, wavy, pyramidal and terraced waves formed on a polycrystalline tungsten surface dependent on crystal orientation after 80 eV helium ion bombardment at 1130 °C. Meanwhile, Liu [22] used a phase-field model to investigate the effect of the surface-energy anisotropy of polycrystalline material on the void evolution during ion irradiation. In addition, the influence of the surface chemical composition and impurity element should also be considered, which played an important role during the formation of surface nanostructures induced by ion irradiation [23,24,25,26].…”

Phase field modelling voids nucleation and growth in binary systems

“…From the formalism of the phase field approach it follows that an emergence of this interface is a result of a competition between the gradient and bulk energy terms in the free energy functional: the gradient energy terms are responsible for the curvature of the interface, whereas its formation is described by the terms corresponding to a free energy decrease [39]. The void shape development is governed by different mechanisms related to: surface energy anisotropy, growth anisotropy of void surfaces, preferential adsorption of atoms on certain surfaces of voids during irradiation [73,74]. In our study, we consider the simplest case of isotropic void surface energy.…”

Irradiation-induced void evolution in iron: A phase-field approach with atomistic derived parameters

“…The critical value of 0.8 assigned for η ensures the formation of void. [14,31] For example, if η < 0.8 and R 1 ≤ P casc , vacancy only emerges in the matrix phase. Usually, the defects are generated stochastically on both spatial and temporal scales under irradiation.…”