Effect of LaH3 additive on microstructures and hydrogen storage properties of V40Ti26Cr26Fe8 alloys prepared by hydride powder sintering method

Abstract

Hydride-Powder-Sintering(HPS) as a new preparation approach was applied in the low cost V40Ti26Cr26Fe8 hydrogen storage alloys successfully, which provides an alternative preparation route for other types of hydrogen storage alloys. V40Ti26Cr26Fe8 alloy exhibits ideal hydrogen absorption-desorption performance after adding moderate content of LaH3. Optimizing sintering process by increasing the sintering temperature and time has improved hydrogen desorption plateau evidently. X-ray diffraction analysis results show that the Ti-Oxide phase basically no longer exists when the LaH3 content is greater than or equal to 3 wt% as compared to that of LaH3 content below 3 wt%. Pressure-Compose-Temperature(PCT) curves show that the hydrogen absorption and desorption capacities increase gradually with the increase of LaH3 content. The lattice parameters calculated by Rietveld refinement has the same variety rule as the hydrogen absorption-desorption capacities with the increase of LaH3 content. It can be inferred that the addition of LaH3 has reduced the content of Ti-Oxide and then the lattice parameters increase, which leads to the improvement of hydrogen performance of the alloy. The most appropriate preparation process is 3 wt% of LaH3 additive with a sintering process 1673 K-6h, correspondingly, the hydrogen absorption and desorption capacities are 3.13 wt% and 1.97 wt%, respectively.