The 500 °C Isothermal Section of the Al-Fe-Pr Ternary System

Phases and equilibria involved in the isothermal section at 500 °C of the ternary Al-Fe-Pr system have been here investigated in the whole composition range by means of X-ray diffraction, optical and scanning electron microscopy, and electron probe microanalysis. Phase equilibria are characterised by the formation of two binary solid solutions, Pr₂(Fe_xAl_1−x)₁₇ with 0.34 ≤ x ≤ 1.00 (hR57–Th₂Zn₁₇) and Pr(Fe_xAl_1−x)₂ with 0 ≤ x ≤ 0.20 (cF24–Cu₂Mg), and four ternary compounds, τ₁-PrFe₂Al₁₀ (oS52-YbFe₂Al₁₀), τ₂-PrFe₂Al₈ (oP44-CeFe₂Al₈), τ₃-Pr(Fe_xAl_1−x)₁₂ with 0.28 ≤ x ≤ 0.44 (tI26-ThMn₁₂) and τ₄-Pr₆(Fe_xAl_1−x)₁₄ with 0.63 ≤ x ≤ 0.81 (tI80-La₆Co₁₁Ga₃), which have been confirmed. The solid solubility ranges of the binary and ternary compounds have been considered and trends of their lattice parameters studied. The complete isothermal section has been obtained and the general features of the section are discussed and compared with those of other ternary systems of light R (La, Ce, Pr, Nd, Sm) with Al and Fe.