Advances in rare-earth-free permanent magnets

Abstract

Recent constraints on availability and cost increase of rare-earth (RE) elements have stimulated a strong interest in the discovery of rare-earth-free materials with excellent permanent-magnet properties. Materials having energy products between alnico and Nd2Fe14B, in the range of 15 to 25 MGOe, would have important applications in energy conversion technologies. In this study, we discuss several approaches to this problem, including the development of novel materials without rare-earth elements, modification of known permanent-magnet alloys, and hard-soft exchange-coupled nanocomposites. Our recent research on rare-earth-free permanent-magnet materials, such as Co-rich Hf-Co and Zr-Co alloys, MnBi:X (X = Pt, Au, Fe), and FePt-based nanocomposites, is reviewed.