An effective route for tuning microstructure and properties of sintered Nd-Fe-B magnets: Low pressure sintering technology

In this study, a novel low pressure sintering method for mass industrial preparing Nd-Fe-B magnets with high performance was proposed. The results indicated that the properties of magnets can be greatly enhanced via low-pressure sintering method by tuning the grain size and rich-RE phase distribution. Under the combined effects of pressure and temperature, the flowability of rich-RE liquid phase was enhanced and which made it easy to achieve liquid phase sintering process, resulting in the close theoretical density and high performance of the sintered magnets. The optimum properties (Br = 14.10kGs, Hcj = 14.11kOe and (BH)max = 46.47MGOe) were obtained at the sintering temperature of 980 °C under 2.0 MPa gas pressure field, which is far below the conventional manufacturing temperature for commercial Nd-Fe-B magnets (1060 °C). This work could offer a valuable method to obtain sintered Nd-Fe-B magnets with superior microstructure and excellent properties.