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Amorphous Nanocomposite Materials

Amorphous Nanocomposite Materials. Presented by: Renée E. Gordon Advisor: Professor Michael McHenry Graduate Student: Changyong Um. Amorphous Nanocomposite Material. FINEMET, NANOPERM, and HITPERM. Nanocrystals are embedded in an amorphous matrix. Rapid Solidification Technique.

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Amorphous Nanocomposite Materials

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  1. Amorphous Nanocomposite Materials Presented by: Renée E. Gordon Advisor: Professor Michael McHenry Graduate Student: Changyong Um

  2. Amorphous Nanocomposite Material. FINEMET, NANOPERM, and HITPERM. Nanocrystals are embedded in an amorphous matrix. Rapid Solidification Technique. Cooling rate: 1 Million Kelvin per second. (106 K/sec) Produces Amorphous Metastable Material. Material is not stable at higher temperatures. If occurs, material is thermally activated and can turn to Crystalline phase. Application: Inductive Component of electronic devices. Good soft magnetic properties. Melt Spinning Process

  3. Nano-Indentation • Indenter is only 100nm in size. • Area of Berkovich Tip : • θ = 65.3° (semi-angle of Berkovich indenter) • hp= plastic depth of penetration • Berkovich Hardness:

  4. Theory • Begins Fully Amorphous. • Gradually becomes paramagnetic (losing magnetic change). • Crystallization begins at ~500oC. • Increase in magnetization. • Curie Temperature of Nanocrystalline phase: 610oC. • Note there are 2 different Curie temperatures. Nanocrystalline Curie Temperature Primary crystallization onset temperature Curie transition FINEMET

  5. Theory • Increase in annealing temperature increases the rate of crystallization. • Morphology Index (n) can be determined from Johnson-Mehl-Avrami Kinetic model. • This (n) indicates the mechanism and dimension of nucleation and growth. • Volume Fraction Transformed: • koJMA= rate constant coefficient • QJMA= activation energy • Volume fracture increase is proportional to the magnetization increase. Isothermal Magnetization Kinetic Data of FINEMET

  6. Results • Shows Hardness as a function of Volume Fraction that has been Crystallized. • When crystallization occurs, nanocrystals form. • These nanocrystals are harder than the amorphous matrix. • The more nanocrystals, the harder the overall material. • Fully Amorphous, Hardness=7-8 GPa. • Saturated (top right), Hardness=14 GPa. • HITPERM expected to act similar to FINEMET and NANOPERM.

  7. Results • Thickness-Dependent Magnetization Curve (from VSM). • Increased thickness results in slower crystallization. • As thickness decreases crystallization occurs faster. • 100 nm reading has “noise”. • 70-80% Volume Fraction of the material crystallizes. NANOPERM

  8. Acknowledgements Changyong Um Professor McHenry MRSEC Wright Patterson Air Force Base Magnetics, A Division of Spang and Co.

  9. Thank you for your time. Questions and Comments.

  10. Extras • Composition of HITPERM: • (Fe,Co)88M7B4Cu1 ; (M=Zr,Nb,Hf) • Composition of NANOPERM: • Fe88Zr7B4Cu1 • Composition of FINEMET: • Fe73.5Si13.5B9Nb3Cu1

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