OPTIMIZATION OF SINTERING CONDITIONS OF LaNi₅-Al SYSTEM FOR HYDROGEN STORAGE SYSTEMS BY THERMODYNAMIC MODELLING

This work presents the results of phase equilibrium modeling in the La-Ni-Al system using the Thermo-Calc software. The aim of the calculations was to optimize the composition and sintering parameters of aluminum-alloyed materials to preserve the CaCu₅-type structure and ensure stable hydride-forming properties. Phase diagram sections were constructed for temperatures of 750–950 ℃ at aluminum concentrations ranging from 5 to 20 wt.%, and corresponding thermodynamic parameters such as Gibbs free energy and enthalpy were calculated. The results showed that at 5–10 wt.% Al, the LaNi₅ phase field is preserved with a minimal amount of secondary phases, while at 15–20 wt.% Al, the formation of NiAl (BCC_B2) intermetallics and rare-earth compounds such as La₂Ni₇ occurs, along with the appearance of a liquid phase. The Scheil solidification calculation revealed that when the critical aluminum threshold of 10 wt.% is exceeded, aluminum redistributes into the liquid phase, leading to the breakdown of the original structure and degradation of the material’s hydrogen storage properties. The obtained data enable the determination of optimal synthesis and alloying conditions for developing efficient next-generation metal hydride hydrogen storage systems.

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