Abstract
For a further improvement to achieve extremely high magnetic properties of Nd-Fe-B sintered magnet, extensive investigation has been done. In order to improve the residual flux density (Br) of this magnet, it is very important to increase the amount of Nd2Fe14B(T1) matrix phase up to 95% with keeping the amount of the Nd1.1Fe4B4 (T2) and Nd-rich phases, which generate the liquid phase in the sintering process, as low as posible and to densify the magnet up to the theoretical value by the liquid phase sintering. Also, in order to increase the value of intrinsic coercivity(iHc) without any additives which decrease the saturated magnetization of R2Fe14B intermetallic compound, it is an essential key technology to control the particle size and its distribution to be fine and uniform. Furthermore, for obtaining the super high energy magnet, it is a fundamental technology to realize the excellent alignment of T1 grains. As a result of these investigation on controlling the chemical composition and the microstructure of this magnet, we have succeeded in obtaining the super high energy products magnet having Br=1.495T(14.95kG), (BH)max=431 kJ/m3 (54.2MGOe), iHc=845kA/m(10.62kOe).
