Effect of hydrogen pressure on hydriding kinetics in the Mg 2− xAg xNi–H ( x = 0.05, 0.1) system

Abstract

The aim of this paper is to study the effect of the initial hydrogen pressure on hydriding kinetics in the two-phase region (α–β) of the ternary alloy Mg 2− x Ag x Ni ( x = 0.05, 0.1). The experiments were carefully performed by a volumetric technique under initial hydrogen pressures ranging from 0.298 to 1.203 MPa at 553 K. The experimental investigation suggests that an increase of the initial hydrogen pressure results in an acceleration of hydriding reacted fraction. A new kinetic model developed in our laboratory recently was successfully applied to this system and the rate-controlling step in the hydriding process was hydrogen diffusion in the β phase. Our study further revealed that a higher content of silver in the Mg 2− x Ag x Ni alloys leads to a faster rate of hydriding; the hydriding kinetics of Mg 2Ni could be improved by a partial substitution of Ag for Mg.