|About this Abstract
||Materials Science & Technology 2012
||In-situ Characterization of Phase Transformations in Materials
||The Influence of Pressure on Crystallization in Nanocomposite Soft Magnetic Alloys
||Alex Leary, Sam Kernion, M. E. McHenry, M. S. Lucas
|On-Site Speaker (Planned)
Nanocomposite materials consisting of small crystalline grains embedded within an amorphous matrix show promise for many soft magnetic applications. These alloys are produced by a three-step process; ingot preparation, rapid solidification to produce the amorphous precursor material, and thermal annealing to grow the crystalline phase. Typically, nucleation agents such as copper additions are added to increase the nucleation density in these alloys. However, Co-rich compositions do not require Cu additions and develop crystalline phases that differ from those predicted by the equilibrium Fe-Co phase diagrams. Specifically, the bcc phase preferentially nucleates in compositions well within the single-phase fcc region. This type of nucleation is homogeneous and fully incoherent due to the amorphous/crystalline interface. The crystallization process for these alloys is explained by a nucleation limited model incorporating mechanical stress and surface energies. Experiments validate the model by influencing the phase type during annealing with an applied hydrostatic stress.