Self-healing ability assessment of irradiated multilayered composites: A continuum approach

Abstract

Atomistic simulations have revealed an unconventional behavior of point defects at interfaces found in multilayer composites synthesized by physical vapor deposition but the observed mechanisms that involve point-defect annihilation are subject to time-scale limitations. So, a mathematical model that describes long-term evolution of point defects in such materials under irradiation is presented in this work. Firstly, the effect of interface point-defect trapping and recombination mechanisms on point-defect concentrations has been studied. In addition, the effect of interface self-interstitial atoms loading, which has been seen during collision cascades, and constitutional vacancies has been studied too. Two interface configurations have been considered between metals in a β-α-β three-layer system (α = Cu and β = Nb, or V), KSmin and KS1. These interfaces correspond to ground-state and defect-free KS structures respectively. The respond to irradiation of the systems investigated here, Cu/Nb and Cu/V, depends on both, interface characteristics and bulk properties. Nonetheless, the influence of the properties of one metal in the point-defect evolution of the other metal is only effective if there are constitutional vacancies at the interface, i.e., for KSmin. Especial attention has been paid to the behavior of the same metal (Cu) when it is surrounded by diverse metals (Nb, or V) with the aim of comparing quantitatively our model predictions with experimental results reported elsewhere. The lower concentration of vacancies in Cu layer of Cu/Nb system at steady state is due to the low mobility of vacancies in niobium.