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Lecture-Toward Development of High Coercivity Permanent Magnets for (Hybrid) Electric Vehicles
Speaker: K. Hono Time: 9:00 am on 25th May 2011 Place: NIMTE, CAS
Abstract The interest in the coercivity mechanism of Nd-Fe-B based sintered magnets has recently been revived in Japan due to the increasing demand to develop Dy-free high coercive Nd-Fe-B magnets for traction motors of (hybrid) electric vehicles. However, the relatively low coercivity (~12 kOe) of Nd-Fe-B sintered magnets limits certain applications such as traction motors of (hybrid) electric vehicles and wind power generators. Although a partial substitution of Dy with Nd in the Nd2Fe14B compound increases the coercivity, this can only be achieved at the expense of the maximum energy product. Due to the recent concern of the scarce natural resources of heavy rare earth elements, finding a new method to increase the coercivity without using Dy has now become the center of current research interest in Japan. In this talk, we will give an overview on our recent efforts towards the development of high coercivity Dy-free Nd-Fe-B permanent magnets. The key approaches are to refine the crystal grain size to a single domain size (~250 nm) and to control the grain boundary chemistry. To establish the ideal microstructure, we have investigated the microstructure-coercivity relationships of various commercial and experimental Nd-Fe-B magnets in multi-scale dimensions using high resolution electron microscopy and atom probe tomography. Based on the microstructure-property relationships for a wide range of Nd-Fe-B magnets, we discuss the ideal microstructure for achieving a coercivity of higher than 25 kOe in anisotropic Nd-Fe-B magnets. Biography Education · Ph.D. Materials Science & Engineering, The Pennsylvania State Univeristy, 1988 · M.S. Materials Science, Tohoku Univeristy, 1984 · B.S. Materials Science, Tohoku University, 1982 Professional Experience · 2006 - present: NIMS Fellow and Managing Director of Magnetic Materials Center (currently, Magntic Materials Unit) · 2004 - 2006: NIMS Fellow and Director of Metallic Nanostructure Group · 2002 - 2004: Director, Metallic Nanostructure Group, Materials Engineering Laboratory, NIMS · 1998 - 2002: Head of 3rd Laboratory, Materials Physics Division, National Research Institute for Metals Adjunct Appointments · 2010.5 - present: Adjunct Professor, GIFT, POSTECH · 2007.4 - 2011.3: Visiting Professor, New Industry Creation Hatchery Center, Tohoku University · 2004.3 - present: Professor, Graduate School of Pure and Applied Sciences, University of Tsukuba · 2003.10 - 2004.3: Professor, Institute for Materials Science, University of Tsukuba |
