EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Grain boundaries migration is considered as a prime cause for several degradation effects in polycrystalline materials. Apart from the development of novel materials, such effects are also crucial for the understanding of other properties of nanocrystals. Although Hydrogen is known to be detrimental to the performance of electronic devices, the exact mechanisms under which hydrogen atoms cause these effects are not fully understood.

To efficiently describe the kinetics of the grain boundaries (GBs), large-scale simulations are required. In this work, we examine the effect of hydrogen on the kinetic properties of GBs using atomistic simulations and Bond Order Potentials and Modified Embedded Atom Method Potentials combined with Density Functional Theory calculations. Our Molecular Dynamics (MD) simulations in Cu demonstrate that annealing temperatures up to 800K are sufficient to cause GB migration via the formation of disconnections and structural transformations. However, GBs migration barrier was found to be affected by the addition of a certain concertation of H interstitial atoms. Since grain boundaries nucleate and release stresses via the emission of dislocations, H was found to hinder the emission of dislocations. Thus our results indicate that H embrittlement leads to the aggregation of stresses in the GBs. To investigate the interaction between H and common dopants such as Ti, Al and Cu vacancies, BOP and DFT methods have been combined with a Knowledge Led Master Code that allows us to investigate all the possible complexes of H atoms and the mentioned point defects. Results showed that H tends to stabilise the GBs while hindering the emission of self-interstitial atoms in the grain boundaries. Dopants like Al and Ti inhibit the mobility of the grain boundaries by reducing the relaxation effects and the GB phase transitions. Finally, linear scaling DFT was used to investigate the interaction of hydrogen with common non-metallic impurities.