Nanostructuration of SmCo₅ Magnets by Spark Plasma Sintering: Optimization of Magnetic Properties

In the context of current climate issues and environmental constraints, green and renewable energies have experienced considerable growth in recent decades. Thus, there has been a renewed interest in the development of electric machines. To achieve this, the optimization of mass saving, volume and magnetic performance in the development of these machines must accelerate and be implemented industrially, particularly in the aeronautical field. The aircraft of the future will therefore require the use of electric machines with very high power densities and efficiencies. To achieve these objectives, one of the essential components to improve is the permanent magnet, and in particular its magnetic properties (increases in coercive field, residual magnetization and specific energy density). These magnets are likely to operate at temperatures above 200 °C. In this context, hard ferromagnetic magnets seem to be the most appropriate. SmCo₅ magnets have a Curie temperature between 720 and 920 °C. In this work we show the impact of grinding time on the magnetic properties of these SPS-treated magnets. This method allows the sintering SmCo₅ magnets while limiting their oxidation and their grain growth. By optimizing the grinding parameters, we obtain magnets with a coercive field of the order of 18,800 Oe. The novelty of this study lies in the optimization of EBSD (Electron Backscatter Diffraction) image analysis using the NLPAR (Non-Local Pattern Averaging Reconstruction) method, combined with advanced image correlation techniques. This approach enabled the precise determination of a grain size distribution centered around 50 nm, offering new perspectives on microstructural control and the enhancement of magnetic performance in SmCo₅ magnets.