Materials Science Seminar: Permanent Magnets for Electric Vehicle Motors: Rare-Earth Reduction and Alternative Material Strategies

Abstract:
The rapid expansion of the electric vehicle market is driving unprecedented demand for high-power-density traction motors that rely on advanced permanent magnets. Sintered Nd-Fe-B magnets currently dominate this application due to their exceptional energy product and thermal stability. However, surging rare-earth demand compounded by ongoing geopolitical tensions has created critical supply-chain vulnerabilities, particularly for heavy rare-earth elements such as dysprosium and terbium. Over the past decade, this has intensified research into both rare-earth-reduced and rare-earth-free magnetic materials. This seminar examines four key areas of this evolving landscape. First, we review the fundamental performance requirements for traction-motor magnets and the current state of the art in sintered Nd-Fe-B systems. Second, we discuss heavy-rare-earth-free nano-Nd-Fe-B magnets, which achieve comparable coercivity and thermal stability through microstructural engineering rather than critical element additions. Third, we explore Nd-lean strategies, including the partial substitution of neodymium with more abundant light rare earths such as lanthanum and cerium, the approaches that have demonstrated energy products exceeding 35 MGOe with up to approximately 40% cerium substitution. Finally, we survey non-rare-earth permanent magnet systems, with particular emphasis on Fe-N and Mn-Bi compounds, which have progressed from laboratory discovery to active commercial development.

Bio:
Professor Cui's research centers on ferroic materials, spanning ferromagnetic, ferroelectric, and ferroelastic systems, with the goal of advancing energy-efficient and renewable energy technologies. His work encompasses permanent magnets (both rare-earth and non-rare-earth based), soft magnetic materials, magnetocaloric materials, and shape-memory and elastocaloric materials. Dr. Cui joined Iowa State University and Ames National Laboratory in 2015. Prior to that, he was a research scientist at Pacific Northwest National Laboratory (2010–2015) and at GE Global Research Center (2005–2010). He earned his Ph.D. from the University of Minnesota in 2002 and completed postdoctoral training at the University of Maryland in 2005. Dr. Cui is the author of more than 120 publications and holds 10 granted patents, two of which received the R&D 100 Award.

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