Effect of Pr content on activation capability and hydrogen storage performances of TiFe alloy

Abstract The poor activation property is the biggest obstacle to the application of TiFe alloy, which can be improved through forming secondary phases in the alloy. In this paper, a new family of the as-cast Ti1.1-xFe0.7Ni0.1Zr0.1Mn0.1Prx (x = 0–0.08) alloys were designed and prepared, and their microstructure and phase composition were examined to determine the effects of alloying with rare earth Pr on the activation property, formation enthalpy of the hydrides, hydriding/dehydriding capacity and kinetics. The results showed that the Pr0 alloy contained the primary phase of TiFe and the residual phase of Ti2Fe. The addition of Pr led to the increase of TiFe phase, the generation of Pr segregative phase, the volume expansion of TiFe lattice cell and the refinement of TiFe grain. Affected by the above factors, the hydrogen storage performances of the Pr-containing alloys were enhanced significantly. The incubation period was 10,000, 200, 0 and 0 s for the Ti1.1-xFe0.7Ni0.1Zr0.1Mn0.1Prx (x = 0–0.08) alloys at 423 K, respectively. The absolute value of the formation enthalpy of the alloys increased with the growth of Pr content, and the hydriding capacity at 1000 s and the hydriding kinetics reached the maximum for the Pr0.02 alloy.