Yukawa and his collaborators at Nagoya University investigated systematically hydrogen (H) absorption and permeation behaviors of membranes of alloys based on Va-group metals (V, Nb and Ta) possessing body centered cubic (bcc) lattice structure. They aimed at developing Va-group alloy  with suppressed susceptibility to hydrogen embrittlement (HE) without sacrificing H permeation performance by alloying Va-group metal A (= V, Nb or Ta) with another metallic constituent M (= Cr, Mo, W, Ru, Fe or Co) possessing affinity to H weaker than that of Va-group metal to H. Yukawa and his co-workers identified some  alloys as favorable H permeation membrane materials. The author carried out statistical thermodynamic analysis for the reported equilibrium pressure-temperature-composition (PCT) relationships for bcc  by Yukawa and co-workers and evaluated parameter Q referring to extent of stabilization of H in  alloy lattice. In this work, the author reviewed correlation between the Qparameter values estimated by statistical thermodynamic analysis and the reported H permeation performances with hope of proposing simple pragmatic guideline for screening bcc  alloy membrane possessing favorable H permeation performance among candidate materials. The review result indicated that alloying element M that leads to suppressed H solubility in bcc  lattice but realizes increased extent of stability for H in  lattice (i.e.  must be considered as the preferred alloying element in view of improved H permeation performance. Then, susceptibility to HE must be evaluated experimentally for thus-screened group of  alloy membranes by H permeation test. Such primary screening process of  on the basis of equilibrium PCTdata would contribute towards reducing number of desired kinetic H permeation experimental test runs on selection of favorable  alloy membrane material from candidate alloys.

H solubility, H permeation alloy membrane, Va-group metals (V, Nb, Ta), statistical thermodynamics.