Nanocrystalline soft magnetic materials produced by continuous ultra-rapid annealing (CURA)

Abstract

Ultra-Rapid Annealing (URA) is an effective means of producing Fe-rich nanocrystalline soft magnetic materials with desirable soft magnetic properties. However, compared to existing annealing techniques, URA presents many unique processing challenges that have so far limited its scalability. In this study, a novel Continuous Ultra-Rapid Annealing (CURA) technique is introduced. This technique is based on a reel-to-reel process and is considered suitable for industrial-scale production. The effectiveness of CURA is evaluated by comparing the microstructural and magnetic properties of a heating-rate-sensitive nanocrystalline (Fe0.8Co0.2)86B14 alloy produced by URA and CURA. It is seen that both techniques produce comparable soft magnetic properties and that the continuous annealing process is stable after a short settling time. A proof-of-concept electric motor containing a CURA prepared nanocrystalline stator core is also demonstrated and compared to an equivalent motor with a Fe-Si steel stator core. It is shown that the CURA production process can be used to produce magnetically soft nanocrystalline materials with complex geometries and that they can deliver increased performance in existing commercial applications.