Solvus behavior of the vanadium-hydrogen and deuterium systems

✍ Scribed by T.B. Flanagan; T. Schober; H. Wenzl

• Publisher: Elsevier Science
• Year: 1985
• Weight: 762 KB
• Volume: 33
• Category: Article
• ISSN: 0001-6160
• DOI: 10.1016/0001-6160(85)90032-x

✦ Synopsis

The solvus data for V-H and V-D exhibit an extended region of linearity when plotted as In Z, against T-t where Z, = [a/(/3 -a)] where a is the H(D)-to-V, atom ratio, at the solvus composition and b is the number of available interstices per metal atom. This behavior contrasts with the Ta-H system which exhibits considerable curvature in the solvus plot over the same temperature range. It is shown that the linearity results from the opposing influences of nonideality and the variation of the solvus enthalpy and entropy with temperature; the latter is due to the occupation of octahedral and tetrahedral interstices in the hydride and dilute phases, respectively. In contrast to the Ta-H(D) system, there is a solvus isotope effect in the V-H and V-D systems and this is explained in terms of the occupation of different interstices in the two coexisting phases.

R&sum&-Le solvus de V-H et V-D presente une region hntaire &endue lorsqu'on trace log Z, en fonction de T-', oti Z, = [a/@ -a)], a &ant le rapport atomique de H(D) a V a la composition du solvus et /I &ant le nombre d'interstices disponibles par atome metallique. Ce comportement est contraire a celui du systeme Ta-H dont le solvus presente une tris forte courbure dans le mime domaine de temperatures.