Role of magnetostriction on power losses in nanocrystalline soft magnets

• Published in: NPG Asia materials Vol. 14; no. 1; p. 44
• Main Authors: Tsukahara, Hiroshi, Imamura, Hiroshi, Mitsumata, Chiharu, Suzuki, Kiyonori, Ono, Kanta
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 20.05.2022; Nature Publishing Group
• Subjects: 639/301/1034/1037; 639/301/119/997; Algorithms; Alternative energy sources; Biomaterials; Chemistry and Materials Science; Crystal lattices; Domain walls; Energy conversion; Energy dissipation; Energy efficiency; Energy Systems; Generators; Magnetic cores; Magnetic fields; Magnetic materials; Magnetization; Magnetostriction; Magnets; Materials Science; Motors; Nanocrystals; Optical and Electronic Materials; Power management; Simulation; Strain; Structural Materials; Surface and Interface Science; Thin Films
• ISSN: 1884-4049; 1884-4057
• DOI: 10.1038/s41427-022-00388-2

Soft magnetic materials are key materials for the magnetic cores used in motors and generators. To improve the energy efficiency of magnetic cores, it is important to understand the mechanism of energy loss under oscillating magnetic fields. Here, we clarify the mechanism of energy loss in nanocrystalline soft magnetic materials (NSMMs), which are candidates for energy-efficient magnetic cores. To investigate the energy loss of an NSMM, it is necessary to consider the interaction between the magnetization and the crystal lattice, i.e., magnetostriction. However, the random distributions of crystalline axes in nanocrystals hinder magnetostriction calculation. We developed a micromagnetic simulation program by formulating the effective fields due to magnetostriction in randomly oriented nanocrystallites. We performed micromagnetic simulations of NSMMs under an oscillating magnetic field and found that the magnetic energy of the moving domain wall dissipates into the elastic energy of the crystal lattice through magnetostriction. These results can enable the design of highly energy-efficient NSMMs. Nanocrystalline magnets: Pinning down puzzling power loss A new algorithm may make it easier to optimize next-generation motors and generators powered by high-efficiency magnetic cores. Alloys known as nanocrystalline soft magnetic materials (NSMMs) are alternatives to steel-based magnetic cores and can be tailored to improve energy conversion in many devices. Hiroshi Tsukahara from the Institute of Materials Structure Science in Tsukuba, Japan, and co-workers report that physical changes in crystal lattices during magnetization may impact power delivery from these alloys. Using models that simulate the motion of up to ten thousand nanoscale crystal grains, the team demonstrated that non-uniform regions of mechanical strain slow down interactions between NSMMs and external magnetic fields. The researchers note that calculations which include both nanoscale and large-scale descriptions of magnetization-induced strain are critical for designing NSMMs with minimal power loss. We formulated micromagnetic simulation models of nanocrystalline soft magnetic materials including effects of magnetostriction, and simulated motions of domain walls to clarify mechanism of energy dissipations in the nanocrystalline soft magnetic materials. The magnetostriction is nonuniformly distributed, and magnetic energy induced by external field is converted into elastic energy due to the magnetostriction. This energy consumption generates an excess loss in the nanocrystalline soft magnetic materials even there is no eddy current. The simulation results enable us to reduce the core loss in the nanocrystalline soft magnetic materials.