Development of a prototype thermodynamic database for Nd-Fe-B permanent magnets

• Published in: Science and technology of advanced materials Vol. 22; no. 1; pp. 557 - 570
• Main Authors: Abe, Taichi, Morishita, Masao, Chen, Ying, Saengdeejing, Arkapol, Hashimoto, Kiyoshi, Kobayashi, Yoshinao, Ohnuma, Ikuo, Koyama, Toshiyuki, Hirosawa, Satoshi
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 31.12.2021; Taylor & Francis Group
• Subjects: 203 Magnetics / Spintronics / Superconductors; 40 Optical, magnetic and electronic device materials; 407 CALPHAD / Phase field methods; 605 Databases, data structure, ontology; Focus on Science and Technology of Element-Strategic Permanent Magnets; Gibbs energy; metastable states; phase equilibria; Review; Thermodynamic database
• ISSN: 1468-6996; 1878-5514
• DOI: 10.1080/14686996.2021.1936627

For the Nd-Fe-B permanent magnets, a prototype thermodynamic database of the 8-element system (Nd, Fe, B, Al, Co, Cu, Dy, Ga) was constructed based on literature data and assessed parameters in the present work. The magnetic excess Gibbs energy of the Nd 2 Fe 14 B compound was reassessed using thoroughly measured heat capacity data. The Dy-Nd binary system was reassessed based on formation energies estimated from ab initio calculations. The constructed database was applied successfully for estimations of phase equilibria during the grain boundary diffusion processes (GBDP) and the reactions in the hydrogenation decomposition desorption recombination (HDDR) processes.