Abstract
Hydrogen embrittlement causes deterioration of materials used in metal–hydrogen systems. Alloying is a good option for overcoming this issue. In the present work, first-principles calculations were performed to systematically study the effects of adding Ni on the stability, dissolution, trapping, and diffusion behaviour of interstitial/vacancy H atoms of pure V. The results of lattice dynamics and solution energy analyses showed that the V–Ni solid solutions are dynamically and thermodynamically stable, and adding Ni to pure V can reduce the structural stability of various VHx phases and enhance their resistance to H embrittlement. H atoms preferentially occupy the characteristic tetrahedral interstitial site (TIS) and the octahedral interstitial site (OIS), which are composed by different metal atoms, and rapidly diffuse along both the energetically favourable TIS → TIS and OIS → OIS paths. The trapping energy of monovacancy H atoms revealed that Ni addition could help minimise the H trapping ability of the vacancies and suppress the retention of H in V. Monovacancy defects block the diffusion of H atoms more than the interstitials, as determined from the calculated H-diffusion barrier energy data, whereas Ni doping contributes negligibly toward improving the H-diffusion coefficient.
Highlights
Hydrogen, which is a clean, efficient, and renewable fuel, is considered as an indispensable energy source for the future owing to the gradual depletion of fossil fuels [1,2].Hydrogen is a light atom that is thought to exhibit nuclear quantum effects, which are crucial in describing some transport properties of protons and H atoms [3]
Conclusions from one octahedral interstitial site (OIS) to another nearest neighbouring (1NN) OIS through various possible diffuWepaths, investigated hydrogen transportation behaviour of Ni-doped sion with eachthe path passing through an intermediate transition state
We investigated the hydrogen transportation behaviour of Ni-doped vanadium solid solution using first-principles density functional theory (DFT) calculations
Summary
Hydrogen, which is a clean, efficient, and renewable fuel, is considered as an indispensable energy source for the future owing to the gradual depletion of fossil fuels [1,2].Hydrogen is a light atom that is thought to exhibit nuclear quantum effects, which are crucial in describing some transport properties of protons and H atoms [3]. To develop hydrogen energy on a large scale, the breakthrough lies in understanding the interactions between hydrogen and materials, such as those related to H-storage and H embrittlement, which can decrease the mechanical properties of metallic materials [4,5,6]. Dense metallic membranes are applied in high-purity hydrogen separation from gaseous mixtures and are likely to form hydrides, especially at high hydrogen partial pressures, degrading the mechanical properties of these membranes [7,8]. Low-activation V has been identified as one of the most crucial first-wall and blanket material for advanced fusion reactors because it has excellent resistance to neutron irradiation, superior high-temperature mechanical properties, and high compatibility with liquid lithium blankets [12,13,14]. V-based solid solution alloys for hydrogen storage, with a body-centred cubic (bcc) structure, are capable of absorbing/desorbing hydrogen fast at room temperature, have higher capacities, and are crucial for MH/Ni full cell technology
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