This conference paper was submitted for presentation at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

Rare-earth permanent magnets, such as Neodymium-Iron-Boron, are essential in any motor and generator application. These materials, however, face two significant challenges: susceptibility to demagnetisation, particularly at edges and corners, and reliance on resource-intensive rare-earth elements. The magnet demagnetising over successive cycles of an externally applied magnetic field weakens the magnets over time, degrading their performance, while the global scarcity and high costs of rare-earth materials raise sustainability concerns. Addressing these issues requires innovative approaches to maintain magnetic performance while reducing rare-earth dependency. One established method is through grain-boundary diffusion. Dysprosium (Dy), a rare-earth element, is introduced to improve coercivity by reducing the demagnetisation field along the grain boundaries and magnet surfaces and corners. Despite its effectiveness, this process increases the use of rare-earth elements, exacerbating supply chain challenges. As such, alternative strategies that achieve similar outcomes without additional rare-earth content must be explored. The work presented here develops and uses a modelling framework to investigate alternative magnetic architectures designed to mitigate demagnetisation without increasing rare-earth content. We first start by developing a 1D model to provide an analysis of cylindrical magnets with varying magnetic profiles. This provides the capability to explore the trade-off between the demagnetisation field and the external field produced by the magnet and shows that certain architectures replicate the effects of reduced magnetisation without relying on introducing Dy. The results are then used to provide validation and design criteria for simulations using COMSOL Multiphysics. The 3D simulations reveal the versatility of non-linear magnetic profiles across three axes, offering significant improvements in magnetic performance. Specifically, applying non-linear magnetic property profiles within the magnets shows a reduction in the demagnetisation field at critical regions, such as edges and corners, with minimal compromise to the external field strength. This model approach also allows us to further optimise the magnetic architecture by concentrating demagnetisation resistance in regions where it is most needed. These advancements enable the design of magnets with reduced rare-earth content, lowering production costs and enhancing sustainability. Additionally, such magnets allow for more efficient use of rare-earth elements, producing a greater number of magnets from the same resource quantity. This work contributes to the development of next-generation permanent magnets, balancing external field performance and demagnetisation resistance while reducing environmental impact. The findings offer a pathway to sustainable magnetic material design, supporting the broader goal of advancing resource-efficient and environmentally responsible technologies.