Combination strategy for high-performance Sm(CoFeCuZr)z sintered permanent magnet: Synergistic improvement of the preparation process

Abstract

In this paper, a new pulverizing approach consisting of strip-casting, hydrogen decrepitation, and jet milling was adopted to produce Sm(Co0.65Fe0.28Cu0.05Zr0.02)7.6 sintered magnet with excellent magnetic performance. By slowing down the rotating speed of the wheel roller during strip-casting, the proportion of the monocrystalline particles is increased, thus the degree of orientation is increased and thereby the remanence is raised. The hydrogen decrepitation and jet milling processes show high pulverizing efficiency, and give to a magnetic powder with uniform composition and concentrated particle size distribution. After the hydrogen absorption process, the presence of residual hydrogen can accelerate the sintering process, promotes grain growth, and ultimately enhances the coercivity and demagnetization curve squareness. The advantages of the combined approach were further explored by optimizing the solid-solution treatment, which can help to form a clear and complete cellular structure, increase the Cu concentration difference between the cell phase and cell boundary phase, and significantly lower the volume fraction of the 2:17R' intermediate phase. Promising magnetic properties are achieved eventually with Br=11.78 kG, Hcj=17.67 kOe, Sr=92.2%, and (BH)max=31.98 MGOe.