Effects of protide structures on hysteresis in Ti-Cr-V protium absorption alloys

Abstract

Ti-Cr-V alloys have a higher protium (hydrogen atom) desorption capacity, but a larger hysteresis in the absorption and desorption processes than AB2 and AB5 type protium absorption alloys. It is desirable that the alloys have a smaller hysteresis for the use of hydrogen storage tanks. This paper aims to clarify the effects of protide (hydride) structures on the hysteresis in Ti-Cr-V protium absorption alloys. It was found that the β phases observed after desorbing at the desorption plateau region had the BCC structure for the alloys (Ti:Cr = 2:3) containing less than 70 at%V, but the BCT structure for the alloys (Ti:Cr = 2:3) containing more than 70 at%V. A major reason for the large hysteresis in the Ti-Cr-V alloys appears to be the a-axial contraction in the absorbing process and the a-axial expansion in the desorbing process as opposed to the c-axial changes.