Fabrication, Microstructure and Properties of In Situ Metallic Glass Matrix Composites

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Fabrication, Microstructure and Properties of In
Situ Metallic Glass Matrix Composites

• Cang Fan
• Department of Materials Science and Engineering
• Johns Hopkins University

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Acknowledgments

• Todd Hufnagel - Department of
  Materials Science, JHU
• Akihisa Inoue - IMR, Tohoku University,
  Japan
• Laszlo Kecskes - Army Research
  Laboratory
• Haito Zhang - Department of
  Mech. Engineering, JHU
• Jean-Francois Molinari - Department of Mech.
  Engineering, JHU
• Mark Koontz - Department of
  Materials Science, JHU
• Jing Li -Department of Materials Science,
  GIT
• Funding
• Japan Science Technology Corporation
• U.S. Department of Energy

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It shows unique properties when grain size down
to nano scale, even amorphous configuration.
Crystalline Structure
Amorphous Structure
Properties of Metallic Glasses

• High Strength (2GPa)
• Large Elastic Limit (2)
• Good Bending Ductility
• (Melt-spun amorphous alloys)

• less even zero plasticity
• upon annealing-induced crystallization the
  properties are generally lost.

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motivations

• Keeping, even improving unique properties of
  metallic glasses.
• High Strength (2GPa)
• Large Elastic Limit (2)
• Preparing samples in bulk size, controlling
  structure in micro even nano size gt to develop
  advanced materials. Solving the problems.
• less even zero plasticity
• losing strength, getting very brittle with
  crystallized or
• precipitated crystalline phases.

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Outline

• Fabrication, Microstructure and Properties
• In Situ Nano-size Particles / Metallic Glass
  Matrix Composites.
• (materials with in Situ nanoparticles
  dispersed in a metallic glass matrix)
• In Situ Micro-size Ductile Crystals / Metallic
  Glass Matrix Composites
• (materials with in Situ ductile particles in
  micro scale dispersed in a metallic glass matrix)

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Experimental
Alloys ltlt Arc Melting

• Structure
• X-ray x-ray diffraction
• DSC Differential scanning calorimetry
• TEM Transmission electron microscopy
• HREM High revolution electron microscopy
• SEM Scanning electron microscopy

Ribbon ltlt melt-spun Bulk ltlt injection or
suction casting

• Mechanical properties
• Instron mechanical testing equipment
• MTS mechanical testing equipment
• Vickers hardness testing equipment

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• Fabrication, Microstructure and Properties
• In Situ Nano-size Particles / Metallic Glass
  Matrix Composites
• (materials with in Situ nanoparticles
  dispersed in a metallic glass matrix)
• In Situ Micro-size Ductile Crystals / Metallic
  Glass Matrix Composites
• (materials with in Situ ductile particles in
  micro scale dispersed in a metallic glass matrix)

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• Nanocrystalline composites 1990s
• Al, Mg based alloys gt higher hardness, higher
  strength.

• However, all of these alloys
• Require high cooling rates of
• above 104 K/s.
• Samples in ribbon shape of 20
• µm thick and 1mm wide.
• ?Tx Tx - Tg, Tg / Tm

• Nano formation ltlt High Nucleation Rate gt
  Lower GFA

• Bulk Nanocrystal/Amorphous Alloys?

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Transmission Electron Microscopy
Melt-spun ribbon
693K, 1.2ks
Zr65Fe5Ni8Cu12Al10
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Enthalpy of mixing and Atomic size for Zr-TM-Al
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DSC Covers (Differential scanning calorimetry)
x 10 Tg 700 K Tx 762 K ?Tx 62 K Tm 1172
K Tg/Tm 0.60
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X-ray diffraction
Zr60Cu30-xPdxAl10 (a) x 0 (b) x 10
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Transmission Electron Microscopy
(a) melt-spun ribbon (b) 705K,
1.2ks Zr60Cu30-xPdxAl10 x 0
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electrolytic polishing, Zr 5 perchloric acid
ethanolUsed solution 1 part nitric acid 3
parts methanol
(a) melt-spun ribbon (b) B.F.I., (c)D.F.I.,
726K, 1.8ks Zr60Cu30-xPdxAl10 x 10
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High-resolution Electron Microscopy
726K, 1.8ks Zr60Cu30-xPdxAl10 x 10
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Zr60Cu30-xPdxAl10 x 10
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Scanning Electron Microscopy
High-resolution Electron Microscopy
Vf 27
Vf 0
Vf 27
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Summary
In Situ Nano-size particles / Metallic Glass
Matrix Composites

• Bulk Nanocrystal/Amorphous Alloys were prepared
  in size of 4 mm diameter, 70 mm long.
• The existence of nanocrystals being only a few
  nanometers in diameter dispersed in an amorphous
  matrix was found to lead to an increase of both
  the strength and the ductility with increasing Vf
  of nanocrystals.