The Evolution of Microstructure and Defect Structure in Manganese-Aluminum-Base Ferromagnets: Pathways to Novel Processing Routes and Enhanced Properties

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0092099 Soffa This research program studies the nature of the phase transformation involved in the formation of the ferromagnetic tau-MnAl (L1o) phase in MnAl-base magnetic materials. The evolution of microstructure and defect structure which governs the development of magnetic properties in bulk alloys and thin films is examined. The research builds on the revelation that the metastable tau-MnAl phase emerges as the product of a massive transformation and that the microstructure and defect structures which evolve depend critically on the mechanistics of this phase transformation. The goal of this investigation is to use the fundamental knowledge of the transformation mechanism as a pathway for the design of new alloying strategies, heat treatments, and processing schemes to tailor the structure-property relationships in these materials. This research should also contribute to our understanding of an important genre of solid-state transformation.%%%These magnetic materials have tremendous potential in futuristic permanent magnet applications and for thin film devices including magnetic recording media. The full potential of the MnAl-base ferromagnets will only be realized when the evolution of microstructure and defect structure can be systematically controlled since their magnetic properties are extraordinarily sensitive to the structural state of the tau-MnAl phase.***