  Hot deformation process is one of the primary methods to produce anisotropic
rare earth permanent magnets. Firstly, rapidly quenched powder flakes with
nanocrystal structure are condensed into the full dense isotropic precursors by
hot pressing process. And then, the prepared isotropic precursors are hot
deformed to produce high-anisotropy uniaxial bulk rare earth permanent magnets,
in which the highly textured structure is obtained in the hot plastic
deformation process. The obtained hot-deformed magnets possess many advantages,
such as near net-shape, outstanding corrosion resistance and ultrafine-grain
structure. The noteworthy effects of preparation parameters employed in
hot-pressing and deformation processes on the magnetic properties and
microstructures characterizations are systemically summarized in this academic
monograph. As a near net-shape technique, hot deformation process has
noteworthy advantages in producing irregular shape magnets, especially for
radially oriented ring-shape magnets with high length-diameter ratio or thin
wall. The difficulties in producing crack-free, homogeneous and non-decentered
ring-shaped magnets are basically resolved through mold design, adjustment of
deformation parameters and application of theoretical simulation. Considering
the characteristics of hot-deformed magnets, such as the grain shapes and
sizes, anisotropic distribution of intergranular phases, etc., there is
practical significance to study and improve the mechanical, electric properties
and thermal stability to enlarge the applicable area of hot-deformed magnets or
ring-shaped magnets.
