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180 Appendix B. Site Reports—Europe Fe 2 B + Nd 2 Fe 14 B nuclei; and (4) recombination yields fine grained Nd 2 Fe 14 B. Several rare earth permanent magnet alloys are studied at IFW using HDDR, including Sm 2 Fe 17 N 3 and Sm 2 Fe 17–x Ga x . Dr. V. Neu IFW, Institute for Metallic Materials, Department of Superconductivity, Magnetism Dr. Neu described NbFeB magnet powders prepared by mechanical alloying. The goal of this work is to obtain high remanent, isotropic Nb-Fe- B powders for polymer-bonded permanent magnets. Mechanical alloying is used to obtain a nanoscale mixture of Nd 2 Fe 14 B and aFe which provides for remanence enhancement via exchange coupling when the grain sizes are < 30 nm. The mechanical alloying provides an amorphous + nc Fe structure which on annealing forms nc aFe + nc Nd 2 Fe 14 B which behaves as a single magnetic phase. The powders can be bonded with polymers and form isotropic magnets with high remanence. In addition some Fe can be replaced by Co which increases the remanence (as well as the Curie temperature) and has provided (BH) max values up to about 150 kJ/m 2 . Dr. Norbert Mattern IFW, Institute for Solid State Analysis and Structural Research, Department of X-Ray Structural Analysis Dr. Mattern described work on soft ferromagnetic materials such as the “finemet”-like alloys (FeNiSiBNbCu) and FeZrB alloys. These materials are made by rapid solidification to obtain amorphous alloys, which are then partially recrystallized to give nanoscale (~ 50 nm) αFe particles in the amorphous matrix. Studies have included composition variations to influence nc grain size and studies of the crystallization kinetics. High nucleation rates and slow growth rates are desired and influenced by the alloy dopants. This research is funded by the federal government and by Vacuumschmelze and Siemens. Dr. Martin Heilmaier IFW, Institute for Metallic Materials, Department of Strength, Environmental Effects Dr. Heilmaier described several projects involving dispersion hardening with nanoscale dispersoids. One project has the goal of dispersion strengthening of Ag to be used as casings for the BiSrCaCuO high T C
Appendix B. Site Reports—Europe 181 superconductor. Mechanical alloying of Ag and Cr 2 O 3 powders is followed by cold pressing, annealing in dry hydrogen, hot pressing at 500°C, and finally hot extrusion at 700°C. The mechanical alloying times were apparently too short in the initial study to provide a uniform distribution of the 40 nm Cr 2 O 3 particles. A bimodal grain structure was observed with mean sizes of 10 µm and 0.3 µm composed of 60% pure Ag grains and 40% Ag grains with the nc oxide dispersoids. Even so, significant Hall-Petch hardening was observed at room temperature, along with increased creep resistance at 500°C in the dispersion-hardened Ag. Another project focuses on mechanical alloying of Ll 2 –(Al,Cr) 3 Ti intermetallic with Y 2 O 3 nanoscale dispersoids of 5 nm size. Dr. Roland Scholl Fraunhofer Institute, Institute for Applied Materials Research, Department for Powder Metallurgy and Composite Materials Dr. Scholl described an in situ data acquisition and monitoring system for a planetary ball mill. This is important for studies of the mechanical alloying/milling processes used for formation of nanocrystalline materials. The device measures the temperature and pressure via a transmitter in the lid of the milling vial. This was done for a Fritsch “pulverisette 5” planetary mill; the work was partially supported by Fritsch. An example was given for milling of Ti and C powders to form TiC. Good time resolution, about 10 ms, is available to monitor the reactions, which can occur during milling and provide feedback to optimize the milling parameters. After the formal presentations and discussions, the WTEC visitors were given a tour of the IFW laboratories. We observed very impressive state-ofthe-art facilities for processing, characterization, and property testing. The dedicated EELS facility referred to in the work of Dr. Golden (above) was particularly noteworthy.
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National Science and Technology Cou
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WTEC Panel on NANOSTRUCTURE SCIENCE
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ABSTRACT This report reviews the st
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Foreword Timely information on scie
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Foreword iii collaboration and thus
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Contents Foreword Table of Contents
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List of Figures 1.1 Organization of
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List of Figures ix 5.12 Granular GM
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List of Tables ES.1 Technological I
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Executive Summary Richard W. Siegel
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Executive Summary xix past decade,
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Executive Summary xxi TABLE ES.2. C
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Executive Summary xxiii blocks, and
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Chapter 1 Introduction and Overview
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1. Introduction and Overview 3 •
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1. Introduction and Overview 5 worl
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1. Introduction and Overview 7 grow
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1. Introduction and Overview 9 lead
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1. Introduction and Overview 11 2.
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1. Introduction and Overview 13 It
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Chapter 2 Synthesis and Assembly Ev
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2. Synthesis and Assembly 17 transi
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2. Synthesis and Assembly 19 probe
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2. Synthesis and Assembly 21 by adj
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2. Synthesis and Assembly 23 blocks
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2. Synthesis and Assembly 25 Self-A
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2. Synthesis and Assembly 27 Figure
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2. Synthesis and Assembly 29 us to
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2. Synthesis and Assembly 31 Brotzm
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2. Synthesis and Assembly 33 Siegel
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Chapter 3 Dispersions and Coatings
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3. Dispersions and Coatings 37 exis
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3. Dispersions and Coatings 39 more
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3. Dispersions and Coatings 41 into
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3. Dispersions and Coatings 43 of N
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3. Dispersions and Coatings 45 oppo
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3. Dispersions and Coatings 47 Kanz
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Chapter 4 High Surface Area Materia
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4. High Surface Area Materials 51 w
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4. High Surface Area Materials 53 F
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4. High Surface Area Materials 55 T
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4. High Surface Area Materials 57 s
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4. High Surface Area Materials 59 T
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4. High Surface Area Materials 61 F
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4. High Surface Area Materials 63 m
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4. High Surface Area Materials 65 I
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Chapter 5 Functional Nanoscale Devi
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5. Functional Nanoscale Devices 69
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Chapter 6 Bulk Behavior of Nanostru
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6. Bulk Behavior of Nanostructured
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Chapter 7 Biologically Related Aspe
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Page 177 and 178: APPENDICES Appendix A. Biographies
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Appendix F. Glossary 2DEG A/D AAAR
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Appendix F. Glossary 329 ESPRIT ESR
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Appendix F. Glossary 331 MA MBE mCP
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Appendix F. Glossary 333 PVDF QCA Q
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Appendix F. Glossary 335 WTEC XAS X
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