IEEE Awards Booklet - 2022 - 12

2022 IEEE MEDALS
IEEE Medal for Environmental and Safety Technologies
Sponsored by Toyota Motor Corporation
Masato Sagawa and John J. Croat
For contributions to the development of rare earth-iron-boron
permanent magnets for use in high-effi ciency motors, generators,
and other devices
The rare earth-iron-boron permanent magnets discovered and
developed independently by Masato Sagawa and John J. Croat
have enabled energy-efficient and environmentally clean highpower
motors integral to electric vehicles, high-torque servomotors
in robotics and flying devices, renewable energy technologies,
and hard disc drives. In early 1982, both researchers discovered
that utilizing iron (Fe), the most abundant magnetic element in
the continental earth's crust; neodymium (Nd), the most abundant
magnetic rare earth element; and a small amount of boron
(B) led to the development of rare earth magnets with lower cost
and much higher energy density. All Nd-Fe-B permanent magnets
are based on the Nd2
Fe14B. The discovery of these NdFeB
magnets overcame the cobalt crisis, which was the major obstacle
for mass production of samarium-cobalt type permanent
magnets during the 1970s. Sagawa is credited with the development
of anisotropic sintered permanent magnets in which the
principal axis of all crystal grains are aligned to produce strong
magnetic flux using a powder metallurgy process. Sagawa further
developed several key technologies including the development of
high coercivity Nd-Fe-B magnets without the use of expensive
and scarce heavy rare earth elements such as dysprosium. Croat's
discovery resulted from his efforts to produce magnetically hard
metastable phases by crystallizing rapidly solidified materials. His
investigations led to the development of a family of highly stable
resin bonded magnets produced from rapidly solidified NdFeB
powders. These powders consisted of small flakes of rapidly solidified
Nd-Fe-B alloys containing submicron magnetically isotropic
grains of the Nd2
Fe14B phase. Although these resin-bonded magnets
produce significantly smaller magnetic flux density because
of the nonmagnetic binder and the random orientation of the
crystallographic axes, they can be rapidly processed into various
shapes with high precision, specifically thin walled, high L/D ring
bonded magnets now used in wide range of motor types. Magnets
with these complex shapes are difficult to produce by the
sintering process. Croat also played a principal role in the development
of mass production technologies of the rapidly solidified
Nd-Fe-B powders and compression bonded magnets.
Recipient of the 2020 Japan Institute of Metals Award, Sagawa
is president of NDFEB Corporation, Kyoto, Japan.
Recipient of the 1994 Outstanding Engineering Achievement
Award from the American Society of Metals, Croat is president of
John Croat Consulting, Inc., Naples, FL, USA.
Scope: For outstanding accomplishments in the application of technology in the fields of interest of IEEE that improve the environment
and/or public safety.
12 | 2022 IEEE AWARDS BOOKLET

IEEE Awards Booklet - 2022

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