Investigation of Mechanical, Thermal, Electrical, and Hydrogen Diffusion Properties in Ternary V–Ti–X Alloys: A Density Functional Theory Study
Résumé
The effects of alloying and hydrogen dissolution on the mechanical, thermal, and electrical properties of vanadium-based ternary alloys were investigated using density functional theory. Our study showed that pure V has a lower solution energy than V–Ti–X alloys. Also, tetrahedral interstitial sites are more favorable than octahedral sites to be occupied by the H atoms. Furthermore, the alloys with eight H atoms have a lower capacity than the pure V system for H-trapping at interstitial sites. These findings suggest that H-dissolution in alloys is less probable than in pure V, and the alloys are more resistant to hydrogen embrittlement, crack propagation, and fracture initiation. Indeed, V–Ti–Al shows a reliable performance and could be a viable non-Pd alloy for hydrogen separation. Studying the mechanical properties of pure V and the ternary alloys revealed that V–Ti–Ni provides the highest durability and better resistance to both external and hydrogen dissolution-induced internal stresses. The V–Ti–Pd alloy has a higher diffusion barrier energy (Eb = 0.1807 eV) than pure V (Eb = 0.1646 eV), indicating that the H atom faces more hindrance when it diffuses across the alloy. Nonetheless, in the hydrogen separation temperature range, the V–Ti–Pd alloy has the largest thermal expansion coefficient (α = 2.048×10–5 K–1), which indicates its poor thermal characteristics. Altogether, the superior mechanical properties of the V–Ti–Ni alloy indicate that it will be resistant to deformation and have a long service life in hydrogen separation applications. The V–Ti–Ni alloy has a higher heat capacity than the others, which is important in exothermic processes like hydrogen separation.
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