Aluminothermic and Magnesiothermic Reduction of Rare Earth Compounds for Production of Alloys: Thermodynamic Evaluations

This chapter delves into the thermodynamic evaluations of aluminothermic and magnesiothermic reduction processes for producing rare earth alloys. The study focuses on three types of rare earth compounds: oxides, chlorides, and fluorides, with a particular emphasis on chlorides. Through systematic calculations using FactSage, the research constructs Ellingham diagrams to assess the relative stability of these compounds. The findings reveal that while aluminum and magnesium are not effective in directly reducing most rare earth oxides, they can facilitate reduction through the formation of intermetallic compounds. The study also investigates the impact of temperature and reactant ratios on the equilibrium phases, highlighting the varying degrees of reduction efficiency for different rare earth chlorides. Notably, magnesium shows a higher reduction capability for yttrium and scandium chlorides compared to aluminum. The research concludes that the thermodynamic activity of reduced rare earth elements plays a crucial role in determining the feasibility of these reduction processes, offering valuable insights for the production of rare earth alloys.