Thermodynamic Calculation Of Phase Diagrams Of Re-Tm(Tm=Mn,Fe,Ni) Binary Systems

The intermetallic compounds formed by rare earth metals（RE）and 3d transition metals（TM=Mn,Fe and Ni）exhibit special physical and chemical properties,and have been used in industrial applications mainly as functional materials,such as permanent magnets,magnetic refrigeration materials and hydrogen storage materials.The RE-Mn-based compounds（e.g.REMn₆Sn₆）show special magnetic properties in magnetic refrigeration materials,while La Ni₅ has been succeeded as a negative electrode material in the field of nickel-metal hydride batteries.Besides,Nd₂Fe₁₄B alloys are the most widely used permanent magnet material.In order to explore these novel functional materials,the phase equilibria and thermodynamic properties of the（TM=Mn,Fe and Ni）binary systems are essential.Therefore,the main contents of the study on the thermodynamic calculation of phase diagram for RE-TM（TM=Mn,Fe,Ni）binary systems are as follows:（1）The experimental phase equilibria and thermodynamic properties of the RE-Mn binary systems were collected by systematic literature research.Based on literature reviews,it is confirmed that the thermodynamic calculation results of RE-Mn（RE=Ce,Pr,Sm,Tb,Er,Tm,Lu and Y）binary systems are not consistent with the experimental data.The thermodynamic calculations of these five systems were performed by the CALPHAD method.The calculated results are consistent with the experimental data,and reasonable self-consistent thermodynamic parameters are obtained.The phase equilibria and thermodynamic properties of thirteen RE-Mn binary systems are systematically discussed based on the reported results and calculations in this paper.It is found that the phase equilibria and thermodynamic properties of thirteen RE-Mn binary systems will change systematically with the increase of the RE atomic number,which is also taken into account in present calculations.（2）Combined with the evaluations of the RE-Fe binary systems and experimental data,thermodynamic calculations of RE-Fe（RE=Tb,Dy,Er,Lu and Y）binary systems are carried out again.The calculated results are accordance with the experimental data and thermodynamic parameters are gained.The thirteen RE-Fe binary systems about phase equilibria and thermodynamic properties are discussed.It is found that the phase equilibria and thermodynamic properties of RE-Fe binary systems change with the increase of the RE atomic numbers.（3）After comprehensive evaluations and analysis of eleven RE-Ni binary systems,it is found that the thermodynamic calculation results of RE-Ni（RE=La,Ce,Nd,Tb and Ho）binary systems are not accordance with the experimental data.Based on the accurate experimental data,the CALPHAD method was used to re-calculate thermodynamically of the above systems,and the accurate self-consistent thermodynamic parameters were gained.The results show that the phase equilibria and thermodynamic properties of the RE-Ni binary systems also show a systematic trend with the RE number increases.This systematic trend for the RE-Ni binary systems was taken into account when optimizing the Tb-Ni and Ho-Ni systems due to limited experimental information.