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Iron-based amorphous and nanocrystal...

Um, Changyong.

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Iron-based amorphous and nanocrystalline nanocomposite soft ferromagnetic materials.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Iron-based amorphous and nanocrystalline nanocomposite soft ferromagnetic materials./
Author:	Um, Changyong.
Description:	122 p.
Notes:	Adviser: Michael E. McHenry.
Contained By:	Dissertation Abstracts International67-04B.
Subject:	Engineering, Electronics and Electrical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3216279
ISBN:	9780542669316

Iron-based amorphous and nanocrystalline nanocomposite soft ferromagnetic materials.
Um, Changyong.

Iron-based amorphous and nanocrystalline nanocomposite soft ferromagnetic materials. - 122 p.

Adviser: Michael E. McHenry.

Thesis (Ph.D.)--Carnegie Mellon University, 2006.

Synthesis → structure → properties relationships have been studied and compared for new multicomponent amorphous alloy systems and amorphous precursors to state of the art magnetic nanocomposite alloys. The research was aimed at comparing and contrasting the crystallization mechanisms (in both bulk and thin film form) in these systems as well as the technical magnetic and mechanical properties deriving from the as-cast and crystallized microstructures. The ultimate goal was to synthesize new alloys with properties which exceeded those of state of the art materials at higher operational frequencies and temperatures of operation.

ISBN: 9780542669316Subjects--Topical Terms:

626636
Engineering, Electronics and Electrical.

Iron-based amorphous and nanocrystalline nanocomposite soft ferromagnetic materials.
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035 $a (UMI)AAI3216279
035 $a AAI3216279
040 $a UMI $c UMI
100 1 $a Um, Changyong. $3 1296566
245 1 0 $a Iron-based amorphous and nanocrystalline nanocomposite soft ferromagnetic materials.
300 $a 122 p.
500 $a Adviser: Michael E. McHenry.
500 $a Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 2183.
502 $a Thesis (Ph.D.)--Carnegie Mellon University, 2006.
520 $a Synthesis → structure → properties relationships have been studied and compared for new multicomponent amorphous alloy systems and amorphous precursors to state of the art magnetic nanocomposite alloys. The research was aimed at comparing and contrasting the crystallization mechanisms (in both bulk and thin film form) in these systems as well as the technical magnetic and mechanical properties deriving from the as-cast and crystallized microstructures. The ultimate goal was to synthesize new alloys with properties which exceeded those of state of the art materials at higher operational frequencies and temperatures of operation.
520 $a Fe-based multicomponent amorphous alloys with nominal compositions of Fe82-xCoxNb3Ta1Mo1B 13 (x = 0, 6, 12, 18, 20.5, 24, 30, 36, and 41) have been evaluated for soft magnetic applications. Preferential Co partitioning into the amorphous matrix during primary crystallization is inferred from thermomagnetic measurements. The alloy with x = 20.5 composition is shown to be the best candidate for soft magnetic applications. In this alloy system, precipitation of nonmagnetic (FeCo)23B6 phase is found to be responsible for an abrupt decrease in magnetization at secondary crystallization temperature. However, a different mechanism of secondary crystallization is demonstrated for the alloy with x = 20.5 composition. The core loss of the alloy with x = 20.5 is found to exceed the commercial Fe-based amorphous magnetic cores in high frequency (higher than 300 kHz) condition and predicted to be comparable with FINEMET nanocomposite cores in high magnetic induction condition (larger than 12 kG).
520 $a Nanocrystallization kinetics of NANONPERM thin films with various thicknesses have been investigated. Thickness-dependent crystallization kinetics were observed from thermomagnetic and time-dependent magnetization measurements. Formation of crystallization layer at the interface between Si substrate and NANOPERM layer affects the crystallization during a post-annealing process. Different grain morphologies were observed at the interface and volume. The different crystallization mechanisms were found to result in the thickness dependent crystallization kinetics.
520 $a Mechanical properties were investigated for FINEMET and NANOPERM nanocomposite alloys by hardness measurements. Hardness is shown to linearly increase with the volume fraction of crystals (VFC). Increasing VFC is hypothetically modeled to induce strains in amorphous matrix and the interface between second phases and amorphous matrix. This strain hardening model is successfully corroborated by an independent study. Increasing plastic strains with increasing VFC were deduced from this model.
590 $a School code: 0041.
650 4 $a Engineering, Electronics and Electrical. $3 626636
650 4 $a Engineering, Materials Science. $3 1017759
650 4 $a Physics, Electricity and Magnetism. $3 1019535
690 $a 0544
690 $a 0607
690 $a 0794
710 2 0 $a Carnegie Mellon University. $3 1018096
773 0 $t Dissertation Abstracts International $g 67-04B.
790 $a 0041
790 1 0 $a McHenry, Michael E., $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3216279