Recent Advances in Co-Based Nanocrystalline and Amorphous Soft Magnets and Their Applications

Nanocrystalline soft magnetic alloys are synthesized through rapid solidification to form a metallic glass precursor followed by partial devitrification. Co-based alloy systems show a unique combination of high temperature stability, tunable magnetic properties through magnetic field and/or applied tension applied during the annealing process, and the formation of nanocrystals comprised of multiple phases as well as a high density of planar defects. The presentation will review fundamental principles of alloy design to achieve multidimensional application requirements as well as recent advances in the development of novel alloy systems specifically engineered for harsh environment applications. In particular, newly developed alloys engineered for application temperatures as high as 500C will be presented and the various factors that must be considered for extreme temperature application of soft magnetic alloys will be discussed including (1) microstructural stability, (2) phase stability, (3) corrosion mitigation, and (4) stability of magnetic properties. Results obtained for fabricated inductors based upon novel engineered alloys will also be discussed including their temperature stability and potential for future deployment in extreme operational conditions relevant for interplanetary surface exploration (e.g. Venus) and subsurface applications such as oil and gas as well as geothermal applications.