Influence of Magnetic Particle Size on the Magnetic and Mechanical Properties of Sintered Nd–Fe–B Magnets

Sintered Nd – Fe – B permanent magnets are widely used in various fields due to their superior magnetic properties. Research has shown that grain refinement can significantly enhance both the magnetic and mechanical properties of sintered Nd – Fe – B magnets. Key factors influencing grain refinement include the strip casting (SC) process and the jet milling (JM) process. This study investigates the effects of SC and JM processes, revealing a close relationship between the magnetic powder particle size distribution and the performance of sintered Nd – Fe – B magnets. The results show that at a copper roller speed of 1.09 m s −1 , the SC thickness is relatively uniform. Compared to a speed of 1.00 m s −1 , the coercivity increases by 0.55 kOe, remanence improves by 0.14 kGs, and the maximum energy product rises by 1.16 MGOe. Additionally, the flexural strength and Vickers hardness of the magnet increase by 52.8 MPa and 37.2 HV, respectively. Furthermore, controlling the JM rotational speed reveals that both excessively slow and fast speeds lead to uneven particle size distribution, reducing the magnet's magnetic and mechanical properties. This work examines the impact of magnetic powder size distribution on grain refinement mechanisms in Nd – Fe – B magnets, integrating SC and JM processes to optimize magnet performance.