Nb-TiCo multiphase alloys are prospective membrane materials for hydrogen permeation. Their composition, such as the initial Nb content, has a great influence on their hydrogen permeability (Φ). What the research hasn’t actually mentioned, however, is whether other elements (e.g. Ti or Co) could affect their hydrogen permeability. To address this question, the effects of the Ti/Co ratio on their solidification path, microstructure and hydrogen permeability have been comprehensively investigated. The results show that the Ti/Co ratio has a significant effect on the solidification direction along the eutectic valley but has little effect on the solidification structure. As the Ti/Co ratio decreases, the volume fraction of the BCC-Nb phase decreases whereas the eutectic phases increase. With these changes, the Φ value increases gradually, which is closely connected to the increasing hydrogen diffusion coefficient. Typically, the Φ value of Nb₄₅Ti₂₅Co₃₀ is 1.03 (∼1.08) times higher than that of Nb₄₅Ti_27.5Co_27.5 (Nb₄₅Ti₃₀Co₂₅ ). This can be attributed to a decrease in the hydrogen diffusion activation barrier and a smaller hydrogen adsorption energy. The present work demonstrates that Nb-TiCo multiphase alloys with higher Φ values can still be exploited by a proper optimum design for the composition, such as the Ti/Co ratio.

Nb-TiCo多相合金是用于氢渗透的预期膜材料。它们的组成（例如初始Nb含量）对其氢渗透率（Φ）有很大影响。然而，研究实际上并未提及其他元素（例如Ti或Co）是否会影响其氢渗透性。为了解决这个问题，已经全面研究了Ti / Co比对其凝固路径，微观结构和氢渗透性的影响。结果表明，Ti / Co比对沿共晶谷的凝固方向有显着影响，但对凝固组织的影响很小。随着Ti / Co比的降低，BCC-Nb相的体积分数降低，而低共熔相的体积分数增加。经过这些更改，Φ值逐渐增加，这与增加的氢扩散系数密切相关。通常，Nb ₄₅ Ti ₂₅ Co ₃₀的Φ值是Nb ₄₅ Ti _27.5 Co _27.5（Nb ₄₅ Ti ₃₀ Co ₂₅）的Φ值的1.03（〜1.08）倍。这可以归因于氢扩散活化势垒的降低和氢吸附能的减小。目前的工作表明，具有较高Φ值的Nb-TiCo多相合金仍可以通过适当的最佳组成设计（例如Ti / Co比）来开发。