Recent trend in coercivity improvement of Nd-Fe-B sintered magnet is to refine the grains size. However, magnetic alignment of fine particles of less than 3 μm is difficult in a large-scale industrial production process. Recently, Hasegawa et al. reported that a high coercivity (μ_0H_c) of 1.8 T can be achieved even for the sintered magnets with an average grain size of 6 μm. This opened up the realistic approach in achieving high coercivity in industrially viable Nd-Fe-B sintered magnets [1,2]. The alloy contains an excess amount of Nd and a small amount of Ga-dopant and the high coercivity was
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