Hydrogen storage in TiZrNbFeNi high entropy alloys, designed by thermodynamic calculations. (27th November 2020)

• Record Type: Journal Article
• Authors: Floriano, Ricardo; Zepon, Guilherme; Edalati, Kaveh; Fontana, Gabriel L.B.G.; Mohammadi, Abbas; Ma, Zhongliang; Li, Hai-Wen; Contieri, Rodrigo J.
• Is Part Of: International journal of hydrogen energy. Volume 45:Number 58(2020)
• Page Start: 33759
• Page End: 33770
• Publication Date: 2020-11-27
• Subjects: High-entropy alloys (HEAs) -- Hydrogen storage -- Metal hydrides -- C14 laves phase -- CALPHAD; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2020.09.047
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The hydrogen storage properties of the novel equiatomic TiZrNbFeNi and non-equiatomic Ti20 Zr20 Nb5 Fe40 Ni15 high entropy alloys (HEAs) were studied. These alloys were designed with the aid of thermodynamic calculations using the CALPHAD method due to their tendency to form single C14 Laves phase, a phase desirable for room-temperature hydrogen storage. The alloys, which were synthesized by arc melting, showed a dominant presence of C14 Laves phases with the (Zr, Ti)1 (Fe, Ni, Nb, Ti)2 constitution and small amounts of cubic phases (<1.4 wt%), in good agreement with the thermodynamic predictions. Hydrogen storage properties, examined at room temperature without any activation procedure, revealed that a maximum hydrogen storage capacity was reached for the equiatomic alloy in comparison to the non-equiatomic alloy (1.64 wt% vs 1.38 wt%) in the first cycle; however, the non-equiatomic alloy presented superior reversibility of 1.14 wt% of hydrogen. Such differences on reversibility and capacity among the two alloys were discussed based on the chemical fluctuations of hydride-forming and non-hydride-forming elements, the volume per unit cell of the C14 Laves phases and the distribution of valence electrons. Graphical abstract: Image 1 Highlights: Novel TiZrNbFeNi HEAs were designed for hydrogen storage at room temperature. HEAs showed the presence of C14 Laves phases and its remained stable after cycling. HEAs exhibits excellent absorption behavior without the need of any activation step. Ti20 Zr20 Nb5 Fe40 Ni‧15 alloy showed superior reversibility than TiZrNbFeNi alloy.