Microstructure Engineering Toward High Cost‐Effective Nd–Fe–B Sintered Magnets: A Review

ABSTRACT

Nd–Fe–B sintered magnets, critical for enhancing electromechanical conversion efficiency and operational stability in wind turbines and electric vehicle drives, are prized for their outstanding coercivity, high remanence, and superior maximum energy product. However, the coercivity–remanence trade‐off, combined with severe imbalances in rare‐earth resource utilization, presents two fundamental bottlenecks hindering the development of cost‐effective high‐performance Nd–Fe–B sintered magnets. To overcome these limitations, significant research efforts are focused on the in‐depth exploration, optimization, and innovative design of microstructures. This review synthesizes the world‐wide advances and the author group's latest findings in multidimensional microstructural engineering, anchored in the characteristic microstructural features formed via powder metallurgy technology. It primarily examines the technical strategies, underlying mechanisms and economic evaluation across grain size and morphology optimization, spatial distribution control of the Nd ₆ Fe ₁₃ Ga phase, grain boundary diffusion sources iteration and process improvements, advancements in dual main‐phase Ce magnets, and unique gradient structure design. The persistent challenges for future Nd–Fe–B sintered magnets development and the emerging role of machine learning in guiding technological process, performance prediction, microstructure characterization, and novel permanent magnets discovery are also highlighted.