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Nanocrystalline Soft Magnetic Iron Alloys

  • Author(s): Clark, Trevor
  • Advisor(s): Mathaudhu, Suveen
  • et al.
Creative Commons 'BY' version 4.0 license
Abstract

There is a desperate need for alternative and renewable energy sources to meet the raising demands of our global technological society. Magnetic materials are uniquely poised to address many of the energy demands including in sectors such as energy generation and transmission, transportation, refrigeration, and manufacturing. Improving material properties for these applications would result in enormous impacts to industry in the form of reduced energy costs and reduced greenhouse gas emissions.

There is a desperate need for alternative and renewable energy sources to meet the raising demands of our global technological society. Magnetic materials are uniquely poised to address many of the energy demands including in sectors such as energy generation and transmission, transportation, refrigeration, and manufacturing. Improving material properties for these applications would result in enormous impacts to industry in the form of reduced energy costs and reduced greenhouse gas emissions.

Nanostructured materials present a promising path forward for improving these magnetic properties. Magnetocrystalline anisotropy has been used to describe how grains at the nanoscale effect coercivity. However, there remains a gap in knowledge for describing how nanoscale features effect other critical magnetic properties such as permeability, domain wall movement, and frequency dependence. Additionally, the fundamental mechanisms by which these properties depend on microstructures are unknown. Probing microstructure, chemistry, and magnetic properties at the nanoscale has proven to be challenging, because of the convolution of magnetic and structural information in common nanoscale characterization techniques. Understanding of how magnetic domains interact within complex nanostructured features including many types of defect interactions is critical for engineering materials that take advantage of these properties. Here several amorphous/nanocrystalline Fe based alloys with a rich variety of defects have been synthesized via a variety of severe shear deformation techniques including high energy ball milling, spark plasma sintering, and high pressure torsion. High resolution chemical mapping and correlated structural data is collected to gain insight on fundamental mechanisms of domain-defect interactions. Aberration-corrected scanning transmission electron microscopy, Lorentz transmission electron microscopy and atom probe tomography analysis methods are also used to correlate magnetic domain behavior with specific nanoscale defects and features.

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