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Nanoscale microstructures and hydrogenation properties of an as-cast vanadium-based medium-entropy alloy.
- Source :
-
International Journal of Hydrogen Energy . Sep2023, Vol. 48 Issue 75, p29230-29239. 10p. - Publication Year :
- 2023
-
Abstract
- Vanadium-based hydrogen storage alloys have been widely investigated; however, alloys in the cast state are typically coarse-grained. In this study, an as-cast V 45 Fe 15 Ti 20 Cr 20 medium-entropy alloy was prepared by arc melting, and microstructural analysis revealed that the alloy was composed of nanocrystals. The initial pretreatment temperature of the alloy was approximately 100 K lower than that of the as-cast coarse-grained alloy. At room temperature, the time required for the alloy to reach 90% saturation was only 140 s, indicating excellent hydrogen absorption kinetics. The alloy is fully activated after two hydrogen absorption/desorption cycles. The phase transformation of the alloy in the early hydrogenation stage was investigated using X-ray diffraction, and the results showed that the BCC phase was completely transformed into the BCT phase when hydrogen uptake was performed for 6 s. Furthermore, the apparent activation energy of dehydrogenation in the present alloy calculated using the Kissinger method was 69.8 ± 0.8 kJ/mol. The pressure-composition-isotherms tests showed that the hydrogen absorption capacity of the alloy at 295 K was 2.12 wt%. The hydrogenation/dehydrogenation enthalpy change of the alloy was calculated by the Van't Hoff equation, which was 30.90 ± 1.47 and 33.95 ± 0.41 kJ/mol, respectively. The present work demonstrates that nanostructured vanadium-based hydrogen storage alloys can be fabricated using traditional casting techniques. Our study also enriches the understanding of the microstructures of medium-entropy alloys, which may provide positive guidance for the design of novel vanadium-based hydrogen storage alloys. • An as-cast V-based medium entropy alloy has a nano-scale microstructure. • Nanostructured alloys have very good kinetic properties at room temperature. • The phase transformations during absorption were studied. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 03603199
- Volume :
- 48
- Issue :
- 75
- Database :
- Academic Search Index
- Journal :
- International Journal of Hydrogen Energy
- Publication Type :
- Academic Journal
- Accession number :
- 169920149
- Full Text :
- https://doi.org/10.1016/j.ijhydene.2023.03.465