Point defect stability in a semicoherent metallic interface

Abstract

We present a comprehensive density functional theory (DFT)-based study of different aspects of one vacancy and He impurity atom behavior at semicoherent interfaces between the low-solubility transition metals Cu and Nb. Such interfaces have not been previously modeled using DFT. A thorough analysis of the stability and mobility of the two types of defects at the interfaces and neighboring internal layers has been performed and the results have been compared to the equivalent cases in the pure metallic matrices. The different behavior of fcc and bcc metals on both sides of the interface has been specifically assessed. The modeling effort undertaken is the first attempt to study the stability and defect energetics of non-coherent Cu/Nb interfaces from first principles, in order to assess their potential use in radiation-resistant materials.

Vacancy assisted He-interstitial clustering and their elemental interaction at fcc-bcc semicoherent metallic interface

“…Moreover, considering their important contribution in processes like migration and clustering of defects in the host matrix, defect-defect and host-defect interactions were also studied in detail. The results of our study agree well with the previous literature 29 , 31 in predicting MDI regions to be the most stable sites for monovacancy and isolated He interstitials. Considering the importance of He trapping on the performance of materials properties, the formation of metallic monovacancy and He atom complexes (up to 5He atoms) at the MDI region of the interfacial layers were also studied.…”

“…On the other hand, He-interstitial finds enough free space to accommodate at interfacial MDI, and that is the reason why formation energy (2.48 eV ) for both layers is less than at NON-MDI region (3.48 eV and 3.22 eV for Cu4 and Nb4 respectively), as explained before 31 . But if we insert a He atom in the Cu3 or Nb3 layers, because of the similar lattice environment, the available space for the interstitial He atom will be almost same for both MDI (3.50 eV at Cu3 and 3.54 eV Nb3) and NON-MDI (3.42 eV at Cu3 and 3.52 eV Nb3) region of that particular layer.…”

“…González et al . 31 expanded the analysis to the He interstitial atoms and the He-vacancy complex in the vicinity of the Cu-Nb semicoherent interface in the KS orientation. In that work, the prominent trapping exerted by the Cu-Nb interface on metallic vacancies and He interstitial atoms were studied with the help of metallic vacancy/He interstitial formation energy and DFT-based defect migration barrier calculations.…”

Energetics of vacancy segregation to [100] symmetric tilt grain boundaries in bcc tungsten

“…For example, Tschopp, Solanki and coworkers have performed extensive atomistic simulations to investigate the effects of GB character on the formation energetics of point defects, such as vacancy922232430, self-interstitial9, hydrogen2526, helium2627, carbon2628 and various other impurities2326. Aiming to mitigate radiation damage, Uberuaga, Demkowicz and coworkers have conducted massive multiscale simulations193132333435363738 to understand the effects of interface structure on point defect segregation, defect mobility, defect recombination and GB sink efficiency. Jiang et al 29.…”

Modeling of Point Defects Annihilation in Multilayered Cu/Nb Composites under Irradiation

“…The mechanisms underlying point defect annihilation at Cu/Nb interfaces have been studied recently by density functional theory (DFT) [47], molecular dynamics [1,11,21,27,34,35,48], and phase field calculations [37]. This provided considerable detail on the atomistic processes taking place on relatively short time scales.…”