MICROSTRUCTURES AND HYDROGEN STORAGE PROPERTIES OF Ti0.7Zr0.3(Cr1-xVx)2 ALLOYS
MA Ping1, WU Erdong1(), LI Wuhui2, SUN Kai3, CHEN Dongfeng3
1 Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 2 School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471003 3 China Institute of Atomic Energy, Beijing 102413
Cite this article:
MA Ping, WU Erdong, LI Wuhui, SUN Kai, CHEN Dongfeng. MICROSTRUCTURES AND HYDROGEN STORAGE PROPERTIES OF Ti0.7Zr0.3(Cr1-xVx)2 ALLOYS. Acta Metall Sin, 2014, 50(4): 454-462.
The crystal structures and phase compositions of Ti0.7Zr0.3(Cr1-xVx)2 (x=0.1, 0.2, 0.3, 0.4) alloys are analyzed by the XRD and SEM. The hydrogen storage properties, activation performance, thermodynamics and high-temperature desorption process of the alloys are investigated by pressure-composition-temperature (P-C-T) and DTA-TG measurements. The results show that the Ti0.7Zr0.3(Cr1-xVx)2 alloys contain multi-phases, i.e. C36 (P63/mmc) and C15 (Fd3m) Laves phases and V-based bcc solid solution phases with different lattice constants. When the content of V in the alloy is low, the alloy basically consists of C36 type of Laves phase and small amount of bcc solid solution phase. As the content of V increases, the C36 type transfers into C15 type of Laves phase, where the probability of forming third type of stacking layers (C layers) increases, and the content of the bcc solid solution also increases. The alloys in bulk can be easily activated at 2 MPa and room temperature. The x=0.1, 0.2 alloys present excellent activation performance even after exposure in air for 20 d. As V content increases, the hydrogen absorption capacity of the alloy increases whereas the plateau pressure decreases. The relative partial molar enthalpy (ΔH) and entropy (ΔS) of hydrogen absorption for the alloys are found to be in the ranges of -7~-28 kJ/mol and -35~ -95 J/(mol·K). The DTA-TG analysis indicates that the hydrogen release from the hydrides of the alloys occur in two dissolving temperatures within the range of 500~600 K, and some residual hydrides have completely decomposed at heating temperature up to 800 K.