Investigation of Metal Amorphous Nanocomposite Materials for use in Axial Flux Motors

Electric motors exist at the core of the modern energy economy, and 21st century electrification demands ever higher performance in efficiency, specific power, and reduction in reliance on rare earth materials. One technological pathway toward these goals in magnetic devices employs Metal Amorphous Nanocomposite (MANC) soft magnetic materials, which offer low AC magnetic losses in the medium frequency range, approximately 1-10 kHz. These materials have been employed successfully in inductors and transformers but have not yet been used extensively in motors due to concerns of mechanical brittleness and processing difficulty. Recent work has shown progress toward scalable processing methods to form MANCs into motor components. The low losses at high frequency mean that MANC motors are likely to be limited in performance by stress rather than loss. Here, we develop new MANC materials and measure the magnetic performance increases brought by new compositions. We develop a method to prepare tensile test specimens of laminated MANCs which allow for testing of motor core mechanical properties. We find that MANCs exhibit damage tolerance when laminated together in magnetic cores, with failure repeatability improving with number of laminated layers. We also analyze how mechanical stress develops in the manufacturing process and motor operation of MANC rotors and how these effects limit the achievable specific power. We then conduct an optimization to determine the maximum motor specific power achievable using MANCs while eliminating rare earth material usage. Finally, we find designs of MANC motors which outperform modern electric vehicle motors which rely on rare earth materials in metrics of efficiency and specific power.