Alloying effects of Ru and W on the resistance to hydrogen embrittlement and hydrogen permeability of niobium

Fundamental effects of W alloying on various properties of NbH phases

“…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.…”

“…Moreover, Nb possesses a good combination of excellent hightemperature mechanical properties as well as corrosion resistance, and could be widely used as high-temperature and hydrogen-related nuclear components [6e8]. Nevertheless, the main disadvantage of Nb in these applications is its poor resistance to hydrogen embrittlement [3,4,9,10].…”

“…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].…”

Ta-W Alloy for Hydrogen Permeable Membranes

“…For example, designed Nb-5 mol%W alloy possesses more than 4 times higher hydrogen permeability than Pd-26 mol%Ag alloy without showing any hydrogen embrittlement. 11) According to the concept for alloy design, it is necessary to reduce the dissolved hydrogen concentration below the DBTC (Ductile-to-Brittle Transition hydrogen Concentration) around H=M ¼ 0:2 in order to improve the resistance to hydrogen embrittlement. For this purpose, the heat of hydrogen dissolution into metals should be reduced.…”