Bente Krogh

Microstructure and hydrogen storage properties of as-cast and rapidly solidified Ti-rich Ti–V alloys

Abstract The goal of the present work was to optimize the phase-structural composition and microstructure of binary Ti 0.8-0.9 V 0.2-0.1 alloys with respect to their hydrogen sorption properties. Application of these alloys is for hydrogen absorption from gaseous mixtures containing substantial amounts of carbon monoxide (CO) at high temperatures. Irrespective of alloy composition, both α (HCP) and β (BCC) phases in Ti 0.8-0.9 V 0.2-0.1 formed single phase FCC hydrides upon hydrogenation in pure H 2 . An in situ synchrotron X-ray diffraction study showed that only the β -phase transformed to the corresponding hydride when the alloy was hydrogenated in a mixture of H 2 +10%CO. Rapid solidification (RS) of the alloy resulted in refined grain sizes both in the Ti 0.8 V 0.2 and Ti 0.9 V 0.1 alloys. Furthermore, RS was found to increase the β -phase fraction in Ti 0.9 V 0.1 , being twice larger than that of the as-cast alloy. Ti 0.9 V 0.1 had a platelike microstructure as observed by scanning electron microscopy (SEM), the plates were about 300 nm thick. The microstructure refinement resulted in a faster kinetics of H desorption as observed by temperature desorption spectroscopy (TDS).