Thermodynamic Analysis of the Formation and Decomposition of Intermetallic Hydrides

Abstract

The formation and decomposition of intermetallic hydrides LaNi₅H₆, TiFeH₂, Ti₂NiH, TiNiH₂, Ti₂CuH_2,7, TiCuH, Ti₃AlH₃, Mg₂NiH₄, Mg₂CuH₃, and ZrMn_2,8H₄ are thermodynamically analyzed in identical conditions. These reactions are competitive and the interface between them is determined by the boundary composition A_xB_yH_nbound. For intermetallic compounds LaNi₅, TiFe, Mg₂Ni, and ZrMn_2,8, the range of stable hydrogenation is accordingly equal to 17, 27, 5, and 17% of the maximum hydrogen capacity, and the rest are the range of metastable hydrides in which the decomposition reactions are limited kinetically. The improvement in kinetics of intermetallide hydrogenation prevents the decomposition of the intermetallides hydrides. It is achieved by the mechanical or catalytic activation of hydrogenation and by the use of heat-conducting non-volatile metal-matrix composites based on intermetallides.