Study of the process of destructive hydrogenation of powder intermetallic systems. I. Thermodynamic analysis of the processes of direct and destructive hydrogenation of intermetallics

Abstract

We have carried out a thermodynamic analysis of the processes of direct and destructive hydrogenation (hydrogenolysis) of the intermetallics LaNi5, LaNi5 − xAlx, TiFe, TiFe1 − xMex (Me = Al, Mn, Co, Ni), TiNi. We have established that the regions where these processes occur are separated by a hydrogenation — hydrogenolysis boundary which is determined by the relative limiting hydrogen capacity, depending on the thermodynamic characteristics of the intermetallic (metal) — hydrogen system and the temperature. The boundary between the hydrogenation and hydrogenolysis regions may be controlled by alloying the intermetallics with elements affecting the thermodynamic characteristics of the hydride system. When intermetallic compounds are used as hydrogen sorbents, in order to avoid destructive hydrogenation we need to work at pressures above the limiting equilibrium pressure for the given temperature.