Structure and Phase Diagram of Ti–V–H System at Room Temperature

Abstract

The structure and phase diagram of 0<x<2.0) have been studied by X-ray diffractometry at room temperature.The following crystallographic phases and their mixtures are idenis discussed in relation to the electronic band structure of this ternary system. (Received October 31, 1986) Keywords: X-ray diffraction, lattice constant, ternary hydride, terminal solubility of hydrogen, electronic band structureSince Nagel and Perkins(1) reported a detailed crystallographic investigation of ternary hydrides Til-y VyHx (0<y<0.5, 1.6<x<2.0), many works have been performed to reveal the electronic(2) (11), thermodynamical(12)(13) and diffusive (14)- (17) properties of this system. Some of these works were concerned with the Ti-rich dihydride-phase region as investigated by Nagel and Perkins, but the others involved wider ranges of V and H concentrations, where few reliable data of crystal structures and phase diagrams were available. For a proper understanding of the above properties, further structural information on this system is required. The objective of the present work is thus to make an X-ray crystallographic investigation of Til-yVyHx over the entire range of compositions (0<y<1.0,0<x<2.0) enough to construct an overall phase diagram for this ternary system at room temperature. The buttons were reversed and remelted four times for homogenization. Since the weight loss during arc-melting was less than 0.1% for all the alloys prepared, the actual composition of each alloy was considered to be very close to the nominal one. These buttons were annealed at 1673K for 48 hours to ensure the homogeneity and subjected to hot-rolling into thin platelets followed by mechanical polishing. They were charged with hydrogen in an apparatus described elsewhere (18)

Hydrogen diffusion in Ti–Nb45 at high hydrogen contents

“…Solid solutions with similar and even higher hydrogen contents were also found in other bcc-alloys [21][22][23]. A comparison of the hydrogen diffusion coefficients in Ti-Nb45 at room temperature with literature data for binary alloys is only possible to a limited degree.…”

Hydrogenation and microstructural study of melt-spun Ti0.8V0.2

“…Presence of titanium metal in the dehydrogenated melt spun ribbons could be explained by a phase separation during the melt spinning process as well as trend to the element segregation in the Ti-V alloys during the hydrogen absorption-desorption cycling [15][16][17]. When titanium separates from the Ti 0.8 V 0.2 solid solution, the titanium fraction in the solid solution phase decreases, so its composition becomes enriched by vanadium, Ti 0.8−x V 0.2+x .…”

Hydrogenation Properties of Vanadium-Based Alloys with Large Hydrogen Storage Capacity

“…Hydrogen content of , and phases are reported to be changed according to alloy composition of V-Ti alloy 7) and V-Ti-Cr alloy. 5) To increase the hydrogen capacity of vanadium-based alloys, influence of composition of alloy on hydrogen content of both of starting point of formation and fully hydrogenated phase for V-rich V-Ti-Cr alloy was investigated.…”