Hydrogenation properties of Ti-Fe-Mn alloy with Cu and Y as additives. (26th January 2017) - Ali, Wajid
Abstract: Activation reduction and hydrogen storage capacity enhancement in TiFe-based materials have been challenging problems for the last few decades. In this study, the Cu and Y were introduced in Ti-Fe-Mn alloy and the modified Ti0.95 Y0.05 Fe0.86 Mn0.05 Cu0.05 alloy was melted via water-cooled copper crucible to investigate its hydrogenation performances including the storage capacity and kinetics. The phase analysis, morphology and chemical composition were carried out by means of X-rays diffraction (XRD), optical microscope (OM) and scanning electron microscope/energy dispersive spectroscopy (SEM/EDS) respectively. Afterward, the hydrogen storage capacity and kinetics were studied. The XRD results confirmed the CsCl order structure of the as-synthesized alloy and the surface morphology studies revealed that the alloy was biphasic in nature, composed of the TiFe alloy matrix and Cu2 Y secondary phase. The results showed that the addition of element Y could be enhanced significantly the hydrogen storage capacity due to the enlargement of lattice parameters and the maximum capacity 1.85 wt% at 20 °C was observed. In addition, the activation and kinetic performances of the hydrogenated alloy could be improved significantly due to the Cu and the intermetallic secondary phase Cu2 Y. The study revealed that the intermetallic secondary phase (Cu2 Y) provided fresh surfaces which accelerated the propagation of hydrogen flux into the alloy. Graphical abstract: The illustration of absorption/desorption performance curves of the Ti-Fe-Mn hydrogenated sample with Cu and Y substitution at various temperature ranging from 20 °C to 60 °C. Highlights: The incorporation of element Y could improve remarkably the hydrogen storage capacity. The addition of element Cu shows a positive effect on reducing the stability of hydride. A novel secondary phase Cu2 Y appears in the SEM/EDS study. The significant improvement in activation and kinetics of hydrided alloy is due the Cu2 Y intermetallic secondary phase.