Phase Equilibria and Thermodynamic Description of the Y–B and Y–Fe–B Systems

The Y–Fe–B ternary system was thermodynamically investigated using the CALPHAD approach, which integrated experimental measurements and ab initio calculations. 11 primary phases and 4 invariant reactions were observed based on microstructure analysis of 27 as-cast and 4 annealed Y–Fe–B ternary alloys by X-ray diffraction and electron probe microanalysis as well as thermal analysis by differential scanning calorimetry. Enthalpies of formation of four Y–B binary compounds and seven Y–Fe–B ternary compounds at ground state were calculated by ab initio and incorporated into the thermodynamic modeling. Reliability of the obtained thermodynamic parameters for the Y–B and Y–Fe–B systems were validated by comparing calculated phase equilibria and thermodynamic data with available experimental data, including isothermal sections, vertical sections, liquidus projection, invariant reactions, enthalpies of formation and Scheil solidification paths. Additionally, a comprehensive reaction scheme of the entire Y–Fe–B system was presented.