Temperature dependence of vacancy concentration and void growth mechanism in Al with constant hydrogen concentration: A first-principles study

Liu, Pengyu; Matsumoto, Ryosuke

doi:10.1016/j.engfracmech.2019.106508

Cited by 4 publications

(1 citation statement)

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“…The H-atoms in the lattice of Al can form hydrides 15 , can interact with vacancies 15 , 19 – 21 leading to the stabilization of these in the material and can also accumulate at other defects leading to changes in local plasticity 18 , 22 . Ultimately the strong interactions between H-atoms and vacancies can lead to the formation of pores both during manufacturing and operation 23 – 27 . Because vacancies are necessary for the absorption 28 and diffusion 29 , 30 of substitutional impurities, the stabilization that H-atoms impart to vacancies will also have effects on the concentration and distribution of other impurities in the material.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen at symmetric tilt grain boundaries in aluminum: segregation energies and structural features

Lousada

Korzhavyi

2022

Sci Rep

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Aluminum is envisioned to be an important material in future hydrogen-based energy systems. Here we report an ab initio investigation on the interactions between H-atoms and common grain boundaries (GBs) of fcc Al: Σ9, Σ5, Σ11 and Σ3. We found that upon segregation to the GBs, single H-atoms can cause displacement of Al-atoms. Increasing their concentration revealed large cooperative effects between H-atoms that favor the segregation when other H-atoms are bound at neighboring sites. This makes these GBs able to accommodate high concentrations of H-atoms with considerable segregation energies per atom. Structural analyses derived from Laguerre–Voronoi tessellations show that these GBs have many interstitial sites with higher symmetry than the bulk tetrahedral interstitial site. Many of those sites have also large volumes and higher coordination numbers than the bulk sites. These factors are the increased driving force for H-atom segregation at the studied GBs in Al when compared to other metals. These GBs can accommodate a higher concentration of H-atoms which indicates a likely uniform distribution of H-atoms at GBs in the real material. This suggests that attempting to mitigate hydrogen uptake solely by controlling the occurrence of certain GBs may not be the most efficient strategy for Al.

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