Carbon-fiber-reinforced bulk metallic glass composites are produced by infiltrating liquid Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 into carbon fiber bundles with diameter of the individual fiber of 5 mum. Reactive wetting occurs by the formation of a ZrC layer around the fibers. This results in a composite with a homogeneous fiber distribution. The volume fraction of the fibers is about 50% and the density of the composite amounts to 4.0 g/cm(^3)

Busch, R.

Choi-Yim, H.

Johnson, W. L.

Kim, C. P.

Masuhr, A.

English

Caltech Authors - Main

APPLIED PHYSICS LETTERS VOLUME 79, NUMBER 10 3 SEPTEMBER 2001Processing of carbon-fiber-reinforced Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk
metallic glass composites
C. P. Kim
W. M. Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena,
California 91125
R. Buscha)
Department of Mechanical Engineering, Oregon State University, Corvallis, Oregon 97331
A. Masuhr, H. Choi-Yim, and W. L. Johnson
W. M. Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena,
California 91125
~Received 4 April 2001; accepted for publication 4 June 2001!
Carbon-fiber-reinforced bulk metallic glass composites are produced by infiltrating liquid
Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 into carbon fiber bundles with diameter of the individual fiber of 5 mm.
Reactive wetting occurs by the formation of a ZrC layer around the fibers. This results in a
composite with a homogeneous fiber distribution. The volume fraction of the fibers is about 50%
and the density of the composite amounts to 4.0 g/cm3. © 2001 American Institute of Physics.
@DOI: 10.1063/1.1390317#Recently developed bulk metallic glass ~BMG! forming
alloys1,2 have interesting engineering properties such as high
yield strength and good corrosion resistance. They are also
interesting matrix materials for composites because of their
low melting points of around 1000 K and due to their high
resistance against heterogeneous nucleation of crystals. It has
been shown that BMG reinforced with metal or ceramics
particulates3–5 as well as metal fibers6 can be successfully
processed and the glassy state of the matrix can be retained
after processing.
Another interesting approach is to introduce carbon fi-
bers into a metallic glass matrix to produce a stiff, light-
weight, and high strength material. In this letter we report on
the processing of carbon fiber reinforced BMG matrix com-
posites. As a matrix material the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5
~Vit 1! alloy is used, which is one of the best BMGs discov-
ered. It will be shown that under proper processing condi-
tions the BMG forming liquid easily wets the carbon fibers
and that this results in uniform fiber distribution.
Carbon fiber of PAN~polyacrylonitrile! type
with a diameter of 5 mm and density of 1.8 g/cm3 are
cleaned in acetone and ethanol and preheated at 1273 K
under vacuum in a quartz tube. Subsequently prealloyed
Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 ~Vit 1! melt is infiltrated into the
bundle of carbon fibers in a vertical quartz tube by applying
an argon pressure of 53104 Pa for 120 s at a temperature of
1173 K. The composites are investigated by scanning elec-
tron microscopy ~SEM!, differential scanning calorimetry
~DSC!, x-ray diffraction, and transmission electron micros-
copy ~TEM!.
Figure 1 shows the backscattered SEM image of the car-
bon fiber reinforced composite. The carbon fibers are uni-
formly distributed in the Vit 1 matrix, and the matrix appears
a!Author to whom correspondence should be addressed; electronic mail:
ralf.busch@orst.edu1450003-6951/2001/79(10)/1456/3/$18.00
Downloaded 12 Jan 2006 to 131.215.240.9. Redistribution subject toto be uniform and free of heterogeneity. The volume fraction
of carbon fibers was estimated to be 50% by image analysis
of the polished cross section of the sample. The carbon fibers
are equally spaced with an average distance of 9 mm. The
density of the composite is 4 g/cm3.
The glass transition and the crystallization behavior of
the amorphous matrix of the composites were investigated in
DSC scans. Figure 2 shows DSC scans of pure amorphous
Vit 1 and carbon fiber reinforced Vit 1 composite using a
heating rate of 0.33 K/s. The DSC scans show that the com-
posite sample exhibits an endothermic heat event character-
istic of the glass transition followed by two characteristic
exothermic heat release events indicating the successive
stepwise transformations from supercooled liquid state to
crystalline phases. Both crystallization patterns are not iden-
tical, because the matrix composition in the composite is
FIG. 1. Backscattered SEM image of carbon fiber reinforced bulk metallic
glass composite.6 © 2001 American Institute of Physics
 AIP license or copyright, see http://apl.aip.org/apl/copyright.jsp
1457Appl. Phys. Lett., Vol. 79, No. 10, 3 September 2001 Kim et al.altered due to the formation of ~ZrTi!–C at the interfaces
between matrix and fibers, which leads to a depletion of the
matrix of Zr and Ti.
Figure 3 shows the x-ray diffraction patterns with Cu Ka
radiation of pure amorphous Vit 1, pure carbon fiber, and the
composite sample. The magnitude of the signal of the pure
carbon fiber can be neglected on the intensity scale of the
pure Vit 1 and the carbon fiber reinforced Vit 1. The x-ray
diffraction pattern of the composite shows a superposition of
a broad maxima typical for the amorphous matrix material
and a number of sharp peaks characteristic for a crystalline
phase, suggesting the presence of a mixture of amorphous
and crystalline phase in this composite. The diffraction peaks
were identified as a ZrC lattice pattern. The formation of a
ZrC layer has been reported in the past where it formed
between Zr57Nb5Al10Cu15.4Ni12.6 and SiC and WC.7 From the
peak shift with respect to pure ZrC, the Ti concentration of
the carbide was estimated to be 7%. No considerable
amounts of other phases were detected within the sensitivity
limit of x-ray diffraction.
The interfaces between carbon fibers and the matrix
were investigated by transmission electron microscopy. Fig-
ure 4 shows the dark field TEM image of an interfacial re-
FIG. 2. DSC thermogram ~heating rate of 0.33 K/s! of carbon fiber reinforce
bulk metallic glass composite and Vit 1.
FIG. 3. X-ray diffraction patterns of the pure amorphous Vit 1, pure carbon
fiber, and a composite sample.Downloaded 12 Jan 2006 to 131.215.240.9. Redistribution subject togion between a carbon fiber and the Vit 1 matrix. The com-
posite was prepared for TEM investigations and EDX
analysis by the standard polishing, dimpling, and ion milling
technique. A carbide reaction zone is observed surrounding
the carbon fibers. The following general observations were
made relative to the interface between the glass matrix and
the carbon fibers. Starting from the carbon fibers a diffusion
zone within the fibers was observed in which traces of Ni
and Cu were found indicating that Cu and Ni diffuses into
the carbon. This zone has a thickness between 0.1 and 0.3
mm. However, since NiC and CuC are thermodynamically
not very stable, especially compared to ~Zr1Ti!C, no indi-
vidual NiC or CuC layers form. A crystalline reaction layer
of 0.3–0.6 mm is observed at the former surface of carbon
fibers. The reaction zone consists of two different layers.
There is a 0.1–0.2 mm ‘‘granular’’ layer and a layer of large
crystals at the matrix interface. Both layers have a ~Zr1Ti!C
structure as the TEM diffraction patterns reveal. The large
crystals are high in Zr; the glass matrix adjacent to these
crystals appeared lower in Zr. The ‘‘granular’’ layer close to
the fibers showed a gradient in the Ti content with more Ti
towards the fiber interface. Reaction zones between bulk me-
tallic glass matrix and reinforcement in which a ZrC or
~Zr1Ti!C layer formed have been previously reported be-
tween SiC and Zr57Nb5Al10Cu15.4Ni12.6 as well as between
WC and Zr57Nb5Al10Cu15.4Ni12.6.4 The formation of
~Zr1Ti!C has been observed at the interface between SiC
and Cu47Ti34Zr11Ni8.7
In conclusion, carbon-fiber-reinforced bulk metallic
glass matrix composites were successfully processed.
~Zr1Ti!C was formed at the interface between carbon fiber
and the matrix. During solidification, no heterogeneous
nucleation in the BMG is observed at the interface between
~Zr1Ti!C and matrix. The metallic matrix retained the amor-
phous state even though Zr is depleted near the ~Zr1Ti!C
interface to some extent. These results suggest that carbon-
fiber-reinforced bulk metallic glass composites are promising
candidates for lightweight, stiff materials with improved me-
chanical properties compared to metallic glass itself.
The authors would like to acknowledge fruitful discus-
sions with Frigyes Szuecs and C. M. Garland for performing
TEM work. This work was supported by the Air Force Office
of Scientific Research ~Grant No. AFS 5 F4920-97-0323!
FIG. 4. Dark field TEM of the interfacial region between a carbon fiber and
the Vit 1 matrix. The diffraction pattern of the imaged region is also shown. AIP license or copyright, see http://apl.aip.org/apl/copyright.jsp
1458 Appl. Phys. Lett., Vol. 79, No. 10, 3 September 2001 Kim et al.and the U.S. Department of Energy ~Grant No. DEFG-03-
86ER45242!.
1 A. Peker and W. L. Johnson, Appl. Phys. Lett. 63, 2342 ~1993!.
2 X. Lin and W. L. Johnson, Mater. Trans., JIM 38, 475 ~1997!.
3 H. Choi-Yim and W. L. Johnson, Appl. Phys. Lett. 71, 3808 ~1997!.Downloaded 12 Jan 2006 to 131.215.240.9. Redistribution subject to4 H. Choi-Yim, R. Busch, U. Ko¨ster, and W. L. Johnson, Acta Mater. 47,
2455 ~1999!.
5 J. Eckert, A. Ku¨bler, and L. Schultz, J. Appl. Phys. 85, 7112 ~1999!.
6 R. B. Dandliker, R. D. Conner, and W. L. Johnson, J. Mater. Res. 13, 2896
~1998!.
7 H. Choi-Yim, R. Busch, and W. L. Johnson, J. Appl. Phys. 83, 7993
~1998!. AIP license or copyright, see http://apl.aip.org/apl/copyright.jsp


Processing of carbon-fiber-reinforced Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk metallic glass composites

APPLIED PHYSICS LETTERS VOLUME 79, NUMBER 10 3 SEPTEMBER 2001Processing of carbon-fiber-reinforced Zr 41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk
metallic glass composites
C. P. Kim
W. M. Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena,
California 91125
R. Buscha)
Department of Mechanical Engineering, Oregon State University, Corvallis, Oregon 97331
A. Masuhr, H. Choi-Yim, and W. L. Johnson
W. M. Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena,
California 91125
~Received 4 April 2001; accepted for publication 4 June 2001!
Carbon-fiber-reinforced bulk metallic glass composites are produced by infiltrating liquid
Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 into carbon fiber bundles with diameter of the individual fiber of 5mm.
Reactive wetting occurs by the formation of a ZrC layer around the fibers. This results in a
composite with a homogeneous fiber distribution. The volume fraction of the fibers is about 50%
and the density of the composite amounts to 4.0 g/cm3. © 2001 American Institute of Physics.
@DOI: 10.1063/1.1390317#ig
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alloys1,2 have interesting engineering properties such as h
yield strength and good corrosion resistance. They are
interesting matrix materials for composites because of t
low melting points of around 1000 K and due to their hi
resistance against heterogeneous nucleation of crystals. I
been shown that BMG reinforced with metal or ceram
particulates3–5 as well as metal fibers6 can be successfully
processed and the glassy state of the matrix can be reta
after processing.
Another interesting approach is to introduce carbon
bers into a metallic glass matrix to produce a stiff, ligh
weight, and high strength material. In this letter we report
the processing of carbon fiber reinforced BMG matrix co
posites. As a matrix material the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5
~Vit 1! alloy is used, which is one of the best BMGs disco
ered. It will be shown that under proper processing con
tions the BMG forming liquid easily wets the carbon fibe
and that this results in uniform fiber distribution.
Carbon fiber of PAN~polyacrylonitrile! type
with a diameter of 5mm and density of 1.8 g/cm3 are
cleaned in acetone and ethanol and preheated at 127
under vacuum in a quartz tube. Subsequently preallo
Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 ~Vit 1! melt is infiltrated into the
bundle of carbon fibers in a vertical quartz tube by apply
an argon pressure of 53104 Pa for 120 s at a temperature
1173 K. The composites are investigated by scanning e
tron microscopy~SEM!, differential scanning calorimetry
~DSC!, x-ray diffraction, and transmission electron micro
copy ~TEM!.
Figure 1 shows the backscattered SEM image of the
bon fiber reinforced composite. The carbon fibers are u
formly distributed in the Vit 1 matrix, and the matrix appea
a!Author to whom correspondence should be addressed; electronic
ralf.busch@orst.edu1450003-6951/2001/79(10)/1456/3/$18.00
Downloaded 12 Jan 2006 to 131.215.240.9. Redistribution subject to AIPh
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are equally spaced with an average distance of 9mm. The
density of the composite is 4 g/cm3.
The glass transition and the crystallization behavior
the amorphous matrix of the composites were investigate
DSC scans. Figure 2 shows DSC scans of pure amorph
Vit 1 and carbon fiber reinforced Vit 1 composite using
heating rate of 0.33 K/s. The DSC scans show that the c
posite sample exhibits an endothermic heat event chara
istic of the glass transition followed by two characteris
exothermic heat release events indicating the succes
stepwise transformations from supercooled liquid state
crystalline phases. Both crystallization patterns are not id
tical, because the matrix composition in the composite
il:FIG. 1. Backscattered SEM image of carbon fiber reinforced bulk meta
glass composite.6 © 2001 American Institute of Physics
 license or copyright, see http://apl.aip.org/apl/copyright.jsp
th
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1457Appl. Phys. Lett., Vol. 79, No. 10, 3 September 2001 Kim et al.altered due to the formation of~ZrTi!–C at the interfaces
between matrix and fibers, which leads to a depletion of
matrix of Zr and Ti.
Figure 3 shows the x-ray diffraction patterns with CuKa
radiation of pure amorphous Vit 1, pure carbon fiber, and
composite sample. The magnitude of the signal of the p
carbon fiber can be neglected on the intensity scale of
pure Vit 1 and the carbon fiber reinforced Vit 1. The x-r
diffraction pattern of the composite shows a superposition
a broad maxima typical for the amorphous matrix mate
and a number of sharp peaks characteristic for a crysta
phase, suggesting the presence of a mixture of amorph
and crystalline phase in this composite. The diffraction pe
were identified as a ZrC lattice pattern. The formation o
ZrC layer has been reported in the past where it form
between Zr57Nb5Al10Cu15.4Ni12.6and SiC and WC.
7 From the
peak shift with respect to pure ZrC, the Ti concentration
the carbide was estimated to be 7%. No considera
amounts of other phases were detected within the sensit
limit of x-ray diffraction.
The interfaces between carbon fibers and the ma
were investigated by transmission electron microscopy. F
ure 4 shows the dark field TEM image of an interfacial
FIG. 2. DSC thermogram~heating rate of 0.33 K/s! of carbon fiber reinforce
bulk metallic glass composite and Vit 1.
FIG. 3. X-ray diffraction patterns of the pure amorphous Vit 1, pure carb
fiber, and a composite sample.Downloaded 12 Jan 2006 to 131.215.240.9. Redistribution subject to AIPe
e
re
e
f
l
e
us
s
a
d
f
le
ity
ix
-
-
gion between a carbon fiber and the Vit 1 matrix. The co
posite was prepared for TEM investigations and ED
analysis by the standard polishing, dimpling, and ion milli
technique. A carbide reaction zone is observed surround
the carbon fibers. The following general observations w
made relative to the interface between the glass matrix
the carbon fibers. Starting from the carbon fibers a diffus
zone within the fibers was observed in which traces of
and Cu were found indicating that Cu and Ni diffuses in
the carbon. This zone has a thickness between 0.1 and
mm. However, since NiC and CuC are thermodynamica
not very stable, especially compared to~Zr1Ti!C, no indi-
vidual NiC or CuC layers form. A crystalline reaction laye
of 0.3–0.6mm is observed at the former surface of carb
fibers. The reaction zone consists of two different laye
There is a 0.1–0.2mm ‘‘granular’’ layer and a layer of large
crystals at the matrix interface. Both layers have a~Zr1Ti!C
structure as the TEM diffraction patterns reveal. The la
crystals are high in Zr; the glass matrix adjacent to th
crystals appeared lower in Zr. The ‘‘granular’’ layer close
the fibers showed a gradient in the Ti content with more
towards the fiber interface. Reaction zones between bulk
tallic glass matrix and reinforcement in which a ZrC
~Zr1Ti!C layer formed have been previously reported b
tween SiC and Zr57Nb5Al10Cu15.4Ni12.6 as well as between
WC and Zr57Nb5Al10Cu15.4Ni12.6.
4 The formation of
~Zr1Ti!C has been observed at the interface between
and Cu47Ti34Zr11Ni8.
7
In conclusion, carbon-fiber-reinforced bulk metall
glass matrix composites were successfully process
~Zr1Ti!C was formed at the interface between carbon fi
and the matrix. During solidification, no heterogeneo
nucleation in the BMG is observed at the interface betwe
~Zr1Ti!C and matrix. The metallic matrix retained the amo
phous state even though Zr is depleted near the~Zr1Ti!C
interface to some extent. These results suggest that car
fiber-reinforced bulk metallic glass composites are promis
candidates for lightweight, stiff materials with improved m
chanical properties compared to metallic glass itself.
The authors would like to acknowledge fruitful discu
sions with Frigyes Szuecs and C. M. Garland for perform
TEM work. This work was supported by the Air Force Offic
of Scientific Research~Grant No. AFS 5 F4920-97-0323!
n
FIG. 4. Dark field TEM of the interfacial region between a carbon fiber a
the Vit 1 matrix. The diffraction pattern of the imaged region is also show license or copyright, see http://apl.aip.org/apl/copyright.jsp
1458 Appl. Phys. Lett., Vol. 79, No. 10, 3 September 2001 Kim et al.and the U.S. Department of Energy~Grant No. DEFG-03-
86ER45242!.
1A. Peker and W. L. Johnson, Appl. Phys. Lett.63, 2342~1993!.
2X. Lin and W. L. Johnson, Mater. Trans., JIM38, 475 ~1997!.
3H. Choi-Yim and W. L. Johnson, Appl. Phys. Lett.71, 3808~1997!.Downloaded 12 Jan 2006 to 131.215.240.9. Redistribution subject to AIP4H. Choi-Yim, R. Busch, U. Ko¨ster, and W. L. Johnson, Acta Mater.47,
2455 ~1999!.
5J. Eckert, A. Kübler, and L. Schultz, J. Appl. Phys.85, 7112~1999!.
6R. B. Dandliker, R. D. Conner, and W. L. Johnson, J. Mater. Res.13, 2896
~1998!.
7H. Choi-Yim, R. Busch, and W. L. Johnson, J. Appl. Phys.83, 7993
~1998!. license or copyright, see http://apl.aip.org/apl/copyright.jsp


https://authors.library.caltech.edu/2968/1/KIMapl01.pdf

Processing of carbon-fiber-reinforced Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk metallic glass composites

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