Dresden 2011 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 23: Phase Transformations I

MM 23.5: Talk

Wednesday, March 16, 2011, 12:00–12:15, IFW D

Advanced Characterization of High Performance Permanent Magnets for Hybrid Electric Vehicles — •Thomas George Woodcock and Oliver Gutfleisch — IFW Dresden, Institute for Metallic Materials, PO Box 270116, 01171 Dresden, Germany

NdFeB sintered magnets have recently found important new applications in electric motors for hybrid electric vehicles (HEV) and in the generators used in wind turbines. The operating temperature of the electric motor in HEV is typically approx. 180°C and therefore magnet grades with high Dy content are required in order to provide a sufficiently large coercivity at such temperatures. The limited availability of Dy has led to a very high and somewhat fluctuating price of that element. Significant research effort has therefore recently been put into reducing the Dy content or eliminating the need for Dy in NdFeB sintered magnets for high temperature applications. In addition to various experimental routes toward achieving this, novel approaches yielding detailed microstructural characterisation are required in order to bring greater understanding of coercivity mechanisms. High resolution SEM and TEM, magneto-optical Kerr microscopy and MFM are routinely used to examine a range of NdFeB materials. Recent developments include the use of aberration-corrected TEM to obtain highest spatial resolution images and the application of electron backscatter diffraction (EBSD) to obtain crystallographic orientation data on a local scale from all the phases present in the microstructure. The combination of EBSD and EDX with high resolution serial sectioning yields 3D orientation and chemical data which will also be discussed.