Thermodynamic Optimization And Calculation Of The Nd/Pr-Fe-B Systems

The rare-earth permanent magnets are the critical materials that enable the conversion of electric energy and the kinetic energy. With the increasing using of Nd, the associated rare-earth elements were unbalanced used. Using ligh-rare earth elements to partially substitude Nd in Nd-Fe-B magnets is a promising way to reduce the Nd-content and price of magnets and at the same time without significant magnetic performance sacrifices. And on the other hand, the discovery and development of the third generation Nd-Fe-B-based permanent magnets were based on the researches of the phase diagram and ternary intermetallic phases of Nd-Fe-B ternary system. Thus, in this work, phase relations and phase diagrams of the light-rare-earth based RE-Fe binary systems and ternary Nd-Fe-B systems will be focused on.(1) Based on gathering, collating and assessment of the published Fe-Pr binary phase diagram data, we designed and prepared some alloys with key components. With thermo-analysis(DTA) method, phase transformation temperature of the alloys were obtained. And using CALPHAD method, Fe-Pr binary phase diagram were thermodynamic optimized. Reliable and self-consistent thermodynamic data to describle the Fe-Pr binary system were obtained.(2) Collect the experimental phase diagram data of the Fe-Nd binary system and to determine the reliablility of these published experimental data. For these variance invarianrt reaction temperatures, further experiment are needed to determine the exact reaction temperature. Combing with the assessed experimental thermochemical data, using CALPHAD method, Fe-Nd binary phase diagram was thermodynamic calculated and a set of reliable thermodynamic data to describle Fe-Nd binary system was obtained.(3) Collect and assess the experimental phase diagram data and thermochemical data of the Fe-B and Nd-B systems. Reliable thermodynamic data to describe these two systems were determined. Combing with the previous determined thermodynamic data of Fe-Nd system, using CALPHAD method, thermodynamic calculated the Nd-Fe-B ternary system, and experimental data matching, self-consistent thermodynamic data to describe the Nd-Fe-B ternary system were preliminarily obtained.