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: The current research on Nb-based H 2 -selective alloys encompasses a wide range of compositions and a variety of systems. Designing alloys with more desirable properties, either individually or in series, remains a great challenge. To this end, a simple physical-chemical parameter matching (PCPM) rule has been established for the first time in this study to accelerate the design of Nb-based hydrogen permeable alloys. Specifically, four parameters – valence electron concentration, mixed entropy, atomic radius difference, and electronegativity difference – were calculated to determine an effective parameter selection window with outstanding permeability. Based on this, six alloys with the formula Nb 30 Hf 35 Co 30 M 5 (M = Fe, Cu, Mo, W, Al, Cr,) were arc melted to verify the newly established PCPM rules. The H 2 permeability of produced samples was further evaluated using a hydrogen permeable test instrument. It was shown that a good match between the four parameters, rather than a single valence electron concentration value, is critical for controlling performance in terms of hydrogen permeation. Additionally, the presence of an impurity phase was confirmed to further deteriorate permeability, even if the PCPM rules were met. The significance of this study lies in introducing a new strategy for screening and exploring H 2 -selective alloys to find the optimal combination of elements that provide better predictions for performance.
Yan et al. (Wed,) studied this question.