NOVEL FERROMAGNETIC MATERIALS WITH IMPROVED MECHANICAL PERFORMANCE

Author

Wesley Alexander Everhart, Missouri University of Science and Technology

Abstract

"The ductility of intermetallics has long been a hindrance to their broad adaptation despite a significant range of properties such as magnetic, half-metallic, and shape memory behavior. The lack of a general theory for the ductility of intermetallics along with the lack of prior art that experimentally measured mechanical properties drives the need for significant investment in many of these novel magnetic materials in order to even understand, let alone correct, poor ductility.

This dissertation includes work that explored the effect of vanadium content and quenching rate on the microstructure and ductility of Fe-Co alloys. Results indicated that a martensitic transformation was responsible for the observed property changes with additions of vanadium as low as 1.77 at. % and at cooling rates as slow as 0.167 °C/s.

A novel technique for predicting the ductility of intermetallics through the use of density functional theory calculations was developed to explain the observed improvements with vanadium additions. The model predicts, and experiments validate, that improved ductility in Fe-Co alloys occurs because vanadium additions drive changes in the anti-phase boundary energies which enable easier cross-slip and thus a shift in fracture mode to transgranular cleavage.

Finally, the developed intermetallic ductility model was applied to the inverse Huesler alloy Mn₂CoAl. Results indicated that Mn₂CoAl is brittle. Changes in stoichiometry were predicted to enable changes in the anti-phase boundary energies and cross-slip energies, but these changes are not sufficient to overcome the driving force for intergranular fracture"--Abstract, p. iv

Advisor(s)

Newkirk, Joseph William

Committee Member(s)

O'Malley, Ronald J.
Bartlett, Laura
Wen, Haiming
Medvedeva, Julia E.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Materials Science and Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2022

Pagination

xv, 139 pages

Note about bibliography

Includes_bibliographical_references_(pages 136-138)

Rights

© 2022 Wesley Alexander Everhart, All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12190

Recommended Citation

Everhart, Wesley Alexander, "NOVEL FERROMAGNETIC MATERIALS WITH IMPROVED MECHANICAL PERFORMANCE" (2022). Doctoral Dissertations. 3248.
https://scholarsmine.mst.edu/doctoral_dissertations/3248