Analysis of hydrogen diffusion coefficient during hydrogen permeation through niobium and its alloys

Fundamental effects of W alloying on various properties of NbH phases

“…Considering that the T site is the predominant location of H in both Nb and Nb 15 W, a probably reasonable explanation could be given to the abovementioned experimental observations in the literature, i.e., it is the higher DH f value which fundamentally induce the decrease of the H solubility and hydrogen embrittlement [4,10,13].…”

“…It should be noted that the selection of Nb 15 W is just to simulate to the experimental composition of Nbe5%W [3,4,10,13]. One H atom is then added, respectively, at the tetrahedral (T) and octahedral (O) sites of BCC Nb and Nb 15 W. As a typical example, Fig.…”

“…Specifically, the composition of Nb 16 H is purposely selected and one W atom is added in Nb 16 H, which is very close to the experimental composition of 5 at. % of W in NbH [3,4,10,13]. The calculated results are extensively compared with experimental observations in the literature, and are discussed in terms of electronic structures, which could provide a deep understanding of various properties of Nb 16 H and Nb 15 WH phases.…”

“…It is revealed that the addition of W could decrease the hydrogen solubility in Nb and therefore improve its resistance to hydrogen embrittlement [3,10]. In addition, the alloying of W can apparently enhance the diffusion coefficient of hydrogen in Nb and improve its hydrogen permeability [4,10,13]. The fundamental mechanism of such a decrease of hydrogen solubility as well as the increase of hydrogen diffusivity, however, has not been reported so far in the literature.…”

The Inverse Problem of Identification of Hydrogen Permeability Model

“…Note that the curves for a narrower pressure range are practically linear, in line with ranges of the Sieverts' law. In a wide range of pressures, the wave-like character of the graphs is observed experimentally [37].…”