Advancements in Magnetic Materials for Cutting-Edge Automotive and Power Electronics Applications (25/07/25)
Speaker and Affliation:
Dr. Ravi Gautam
Post-doctoral researcher, Green Magnetic Materials Group,
Research Center for Magnetic and Spintronics Materials,
National Institute for Materials Science (NIMS), Tsukuba, Japan
When?
25th July, 2025 (Friday), 3.00 PM (India Standard Time)
Where
KPA Auditorium, Dept. of Materials Engineering, IISc, Bangalore
Abstract:
Magnetic materials are essential for improving the efficiency, performance, and miniaturization of electromechanical and power electronics systems. Given escalating global energy demands, even incremental improvements in these materials significantly influence energy conservation and economic sustainability. Currently, non-oriented Si-steel, exhibiting magnetic induction of 1.7 – 2.0 T, is widely used soft magnetic material due to its high electrical resistivity and low core losses. However, its performance is limited by increased core losses at high switching frequencies and brittleness, restricting its suitability for advanced applications. Addressing this challenge, our research has developed Fe-P-based alloys through a wrought metallurgy process involving induction melting, forging, and rolling into thin sheets (~0.5 mm), followed by optimized two-step heat treatments [1]. This approach yields Fe3P nanoprecipitates uniformly dispersed within a coarse grain α-Fe matrix, significantly minimizing domain wall pinning and enhancing the electrical resistivity. These alloys exhibit superior magnetic properties. including high saturation magnetization (~2.0 T), low coercivity (<50 A/m), high electrical resistivity (~40 µΩ cm), and notably reduced core losses (~185 at 1 kHz, 1 T). Demonstrating comparable or superior performance to commercial Si-steel, these alloys have been successfully scaled up and automotive components prototypes, including claw-pole alternators and brushed DC motors, have been fabricated, demonstrating material accessibility and achieving excellent prototype performance. To further address high-frequency limitations and meet the increasing demands of advanced power electronics operating at elevated frequencies, we employed a novel approach integrating nanostructure and magnetic domain structure engineering. Utilizing melt-spun techniques, ultra-low core loss, flexible Fe-enriched amorphous ribbons were developed [2]. Controlled heat treatment induced partial nanocrystallization of α-Fe within an amorphous matrix and introduced a unique narrow-stripe magnetic domain structure exhibiting perpendicular magnetic anisotropy. Consequently, the magnetization mechanism transitioned from conventional domain wall movement to magnetization rotation, significantly reducing core losses (< 75 W/kg at 10 kHz, 1 T). This methodology, validated across several nanocrystalline soft magnetic materials, underscores the critical importance of precise microstructural control. The detailed correlation between composition, processing, microstructure, and magnetic properties, supported by advanced characterization techniques (TEM and 3DAP), will be presented. Additionally, the discussion will explore how nanostructure engineering strategies extend material functionalities, particularly as magneto-thermoelectric materials for transverse thermoelectric conversion, significantly contributing toward sustainable energy solutions [3].
References:
[1] Ravi Gautam et. al., JMMM, 493, (2020) 165743.
[2] Ravi Gautam et. al., Nat. Commun., 2025 (Accepted).
[3] Ravi Gautam et. al., Nat. Commun., 15, (2024) 2184.