Hydrogenation features of TiZrHfNbTa high-entropy alloy produced by calcium-hydride synthesisстатья
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Дата последнего поиска статьи во внешних источниках: 10 июля 2024 г.
Аннотация:A high-entropy alloy TiZrHfNbTa has been synthesized by a method of the mutual reduction of the higher oxides of corresponding metals with calcium hydride. The alloy structure was characterized and hydrogen absorption properties were studied. The alloy of overall equiatomic composition TiZrHfNbTa consists of two BCC phases with unit cell parameters of 3.419 and 3.328 Å. The distribution of the elements was established as follows: Ti0.21Zr0.24Hf0.24Nb0.25Ta0.06 (BCC-I) and Ti0.15Zr0.05Hf0.10Nb0.08Ta0.62 (BCC-II). The hydrogenation behavior of the alloy under different conditions was thoroughly studied. It was shown that complete hydrogenation resulted in the formation of FCC-type (H/M → 2) and BCT-type hydrides (H/M → 1) from BCC-I and BCC-II, respectively. Under low hydrogen pressure (< 212.8 Torr), BCC-I absorbed up to 0.33 at. H/M within a solid solution without changing the structural type. According the kinetic analysis, this process can be described as a second order reaction with activation energy of 102 kJ/mol. The BCC-I-based solid solution is capable of retaining hydrogen in a deep vacuum at a temperature of 430 °C. The fast kinetics of hydrogen absorption and high thermal stability allow us to suggest the studied two-phase TiZrHfNbTa alloy as a promising getter for vacuum devices.