Thermodynamic Calculations of the Rare Earth Permanent Magnets: Fe-RE Binary Systems

As the key sub-binary systems in the rare-earth (RE) permanent magnetic materials with excellent magnetic properties (e.g. Nd-Fe-B, Sm-Fe-N magnets), the Fe-RE binary systems were investigated widely due to the industrial applications of permanent magnets. In this work, the experimental data of phase equilibria and thermodynamic properties of the Fe-RE binary systems (RE=La, Ce, Pr, Nd) in the published literature are reviewed firstly. Based on available phase equilibria data and thermodynamic data, the Fe-RE binary systems are assessed thermodynamically using the CALPHAD method. As a result, further experimental information and thermodynamic calculations will be both required in order to develop thermodynamic database of the RE-Fe-B ternary systems, which is very useful to study the relations between alloy composition, microstructure and magnetic properties of novel Nd-Fe-B-based permanent magnets.