材料科学および工学ジャーナル

Investigation of dehydrogenation of Ti-V-Cr alloy by using in-situ neutron diffraction

Abstract

Viney Dixit

Hydrogen is considered as an attractive energy carrier because of its high energy density and pollution-free nature. Among various materials, body centred cubic (BCC) solid solutions and alloys are considered to bepromising hydrogen storage alloys. These alloys also have some drawback, one of them is slow activation (difficulty in first hydrogenation). In order to solve this problem, a heat treatment is usually required before the first hydrogenation. It has recently been found that adding7Zr+10Ni to Ti50V20Cr30 alloy eliminates this additional step of heating and this alloy absorbed 3.6 wt.% of hydrogen in 12 minutes. In present work Pressure-composition isotherm of the alloy is measured which revealed that alloy desorbed 1.6 wt% of hydrogen at 150oC. The evolution of the crystal structure upon dehydrogenation was investigated by in-situ neutron diffraction. A fully deuterated sample was heated from 120oC to 266oC under vacuum and neutron diffraction patterns were recorded as a function of temperature. It was found that the alloy started to desorb very quickly at 200 oC. The amount of fcc phase was monitored using the relative intensity of the fcc phase compared to a standard. Crystal structure and morphology of the samples have been studied by the XRD and SEM analysis respectively. Hydrogenation studies were carriedout by using the home-made hydrogen titration system