Magnetic Properties and Microstructure Studies of Hot-Deformed Nd-Fe-B Magnets With Zr Addition

We synthesized bulk isotropic and anisotropic Nd
_13.5
Fe
_77.5
Co
₃
B
₆
and Nd
_13.5
Fe
_76.5
Co
₃
Zr
₁
B
₆
magnets by spark plasma sintering (SPS). For hot-pressed magnets, the values of remanence (B
_r
) and coercivity (H
_ci
) decreased with addition of Zr. After hot-deformation, it was difficult to obtain the desired alignment for Nd
_13.5
Fe
_76.5
Co
₃
Zr
₁
B
₆
magnets, which had a lower degree of texture compared with Nd
_13.5
Fe
_77.5
Co
₃
B
₆
even at a higher than 65% deformation ratio. The research on the microstructure of hot-pressed and hot-deformed magnets shows that Zr addition made the grain finer for hot-pressed magnets and after hot-deforming there were still plenty of areas of poor texture where the content of Zr was higher than 1 at% according to the results of energy-dispersive spectroscopy. It reveals that Zr addition could retard the grain growth and the development of texture during hot-pressing and hot-deforming.