Thermodynamic reassessment of the La-Ni system

Taking into account the composition range of the LaNi5 phase and its influence on hydrogen absorption, the La-Ni system has been reassessed. A consistent set of thermodynamic functions for this system has been obtained. The substitution solution model has been used to describe the liquid, FCC, and BCC phases. The DHCP phase has been simplified as pure La element. According to the structure, the LaNi5 phase has been described by three sublattice model (La,Ni)1(Ni,La)2Ni3. The other intermetallic compounds (La3Ni, La7Ni3, LaNi, La2Ni3, La7Ni16, LaNi3, α-La2Ni7, β-La2Ni7) have been treated as stoichiometric compounds. The calculated phase diagram and thermodynamic quantities agree well with the experimental values. (orig.)