# Presentation: 823575

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

- Cang Fan
*Department of Materials Science and Engineering*
*Johns Hopkins University*

## 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

## It shows unique properties when grain size down to nano scale, even amorphous configuration. 

- Crystalline Structure

- Amorphous Structure

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

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

- Properties of Metallic Glasses

## 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 => to develop advanced materials. Solving the problems.
-    less even zero plasticity
-    losing strength, getting very brittle  with crystallized or
-          precipitated crystalline phases.

## 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)

## Experimental

- Alloys <<= Arc Melting

- Ribbon <<= melt-spun
- Bulk <<= injection or
- 	suction casting

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

- Mechanical properties:
- Instron mechanical testing equipment
- MTS mechanical testing equipment
- Vickers hardness testing equipment

## 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)

*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)

## Nanocrystalline composites: 1990’s
	Al, Mg based alloys => higher hardness, higher strength. 

- 	Al, Mg based alloys => 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.
-       ΔTx = Tx - Tg,    Tg / Tm

-     Nano formation <<= High Nucleation Rate => Lower GFA

-     Bulk Nanocrystal/Amorphous Alloys?

## Transmission Electron Microscopy 

- Zr65Fe5Ni8Cu12Al10

- Melt-spun ribbon

- 693K, 1.2ks

- Transmission Electron Microscopy

## Enthalpy of mixing and Atomic size for Zr-TM-Al

## DSC Covers (Differential scanning calorimetry) 

*x = 10*
*T**g* = 700 K
*T**x* = 762 K
*Δ**T**x* = 62 K
*T**m* = 1172 K
*T**g**/T**m* = 0.60

## X-ray diffraction

- Zr60Cu30-xPdxAl10
- (a) **x = 0**; (b) **x = 10**;

## Transmission Electron Microscopy 

- (a) melt-spun ribbon; (b) 705K, 1.2ks
- Zr60Cu30-xPdxAl10  **x = 0**

## electrolytic polishing, Zr: 5% perchloric acid + ethanolUsed 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**;

## High-resolution Electron Microscopy 

- 726K, 1.8ks
- Zr60Cu30-xPdxAl10  **x = 10**;

## Zr60Cu30-xPdxAl10  x = 10;

## Slide 17

## Slide 18

## Scanning Electron Microscopy 

*V**f* = 0%

*V**f* = 27%

*V**f* = 27%

- High-resolution Electron Microscopy

## Summary

- 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 *V**f* of nanocrystals.

*In Situ* Nano-size particles / Metallic Glass Matrix Composites