Phase equilibria in the Fe–La–Si ternary system

The isothermal section of the phase diagrams at 1173, 1373 and 1573 K and vertical section phase diagrams in La(Fe1−xSix)13 (0.07≦x≦0.40) and Fe95Si5–La33.3Fe33.3Si33.3 (at. %) sections were experimentally determined mainly using X-ray diffractometer (XRD), electron probe microanalyzer (EPMA) and differential scanning calorimeter (DSC). The obtained phase diagrams showed that six ternary intermetallic compounds (IMCs), including the cubic NaZn13-type La(Fe1−xSix)13 phase (τ1) and the tetragonal Ce2Ni17Si9-type La(Fe1−xSix)13 phase (τ2), exist at temperatures over 1173 K at least and that most of the ternary phases, except the τ1 and τ2 phases, have only small solubility ranges from their stoichiometric compositions. It was also found that the τ1 and τ2 phases form by the following peritectic reactions: αFe (or LFeSi) + LLa + LaFe2Si2 → τ1 at about 1665 K and τ1 + LFeSi + LaFe2Si2 → τ2 at about 1623 K, respectively.