Equilibria in Ce xLa 1− xNi 5− yAl y- H2 systems at subcritical and supercritical parameters

Abstract

Equilibria in Ce x La 1− x Ni 5− y Al y -H 2 systems ( x = 0−0.8; y = 0−0.6) were studied in a wide pressure range from 0.1 to 40 MPa. Isotherms, isobars and polytherms were investigated. It has been established for a narrow interval of alloy compositions ( x ≥ 0.5 and y ≤ 0.1) that a metastable hydride phase occurs in these systems. The metastable phase exists both for supercritical thermodynamic parameters and for subcritical thermodynamic parameters. The conditions of metastable-state formation (stable hydride heating in hydrogen at a constant or increasing high pressure) are probably induced by factors similar to those defining the phenomena of the “immobilized hydride phase” and the “aged hydride phase”.