Phase relationship in the Tb–Fe–Cr ternary system at 600 °C

The phase relationships in the Tb–Fe–Cr ternary system at 600 °C have been investigated mainly by X-ray diffraction analysis and first-principles density functional theory calculations. The result shows that the isothermal section consists of 9 single-phase regions, 16 two-phase regions and 8 three-phase regions. The compound TbFe12−xCrx with the ThMn12-type structure is found to have a broad solubility ranging from x = 1.4 to 2.6. The XRD patterns and total-energy calculations suggest that Tb2Fe17 crystallizes with the Th2Zn17-type rhombohedral structure under our experiment conditions. The solid solutions in this ternary system are formed by the substitution of Fe by Cr. The maximum solid solubilities of Cr in (αFe), Tb2Fe17, Tb6Fe23, and TbFe2 are about 17, 12.5, 3, and 7 at.% Cr, respectively.

► The isothermal section of the Tb–Fe–Cr phase diagram at 600 °C was constructed.
► The Tb2Fe17 crystallizes with the Th2Zn17-type rhombohedral structure at 600 °C.
► The solubility of Cr in Tb2Fe17, Tb6Fe23, and TbFe2 were 12.5, 3, and 7 at.% Cr.