Journal of Minerals and Materials Characterization and Engineering, 2012, 11, 1075-1080
Published Online November 2012 (http://www.SciRP.org/journal/jmmce)
Fabrication and Characterizations of Mechanical
Properties of Al-4.5%Cu/10TiC Composite by
Anand Kumar*, Manas Mohan Mahapatra, Pradeep Kumar Jha
Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee, India
Email: *email@example.com, firstname.lastname@example.org
Received July 5, 2012; revised August 7, 2012; accepted August 15, 2012
Addition of reinforcement such as TiC, SiC, Al2O3, TiO2, TiN, etc. to Aluminium matrix for enhancing the mechanical
properties has been a well established fact. In-situ method of reinforcement of the Aluminium matrix with ceramic
phase like Titanium Carbide (TiC) is well preferred over the Ex-situ method. In the present investigation, Al-Cu alloy
(series of 2014 Aluminiu m alloy) was used as matrix and reinforced with TiC using In-situ process. The Metal Matrix
Composite (MMC) material, Al-4.5%Cu/10%TiC developed exhibited higher yield strength, ultimate strength and hard-
ness as compared to Al-4.5%Cu alloy. Percentage increase in yield and ultimate tensile strengths were reported to be
about 15% and 24 % respectively whereas Vickers hardness increased by about 35%. The higher values in hardness in-
dicated that the TiC particles contributed to the increase of hardness of matrix. Fractured surface of the tensile specimen
of the composite material indicated presence of dimpled surface, indicating thereby a ductile type of fracture. During
the fabrication of composite, reaction products such as Al3Ti, Al2Cu and Al3C4 were identified with various morpho-
logies and sizes in metal matrix.
Keywords: In-situ; Metal Matrix Composites; TiC reinforcement; Mechanical Characterization
Over the past few decades, researchers have emphasized
on production of light and strong materials. Aluminium
based metal matrix composite s are the advanced materials
with superior properties which are actively being sought
for engineering applications. In recent years, Al based
composite materials have gained significance in aero-
space, automotive and structural applications due to their
enhanced mechanical properties and good stability at
high temperature. The necessary characteristics of advan-
ced materials include high specific modulus, stiffness,
strength, hardness, ductility, corrosion resistance, low
heat expansion coefficient and so on .
The aim of designing the metal matrix composite ma-
terials is to combine the desirable properties of metal
(high strength and ductility) and ceramics (high modulus
and stiffness). In order to achieve the optimum mechani-
cal properties, it is essential to achieve the uniform dis-
tribution of reinforcement within the matrix. Aluminium,
Silicon, Copper, Titanium, Magnesium, and Nickel met-
als are widely used for preparation of metal matrix in
composites materials where as monofilaments, whiskers,
fibers or particulate types are widely used as reinforce-
ment phases in Metal Matrix Composites (MMCs). There
are many processing techniques which have been deve-
loped for fabricating Metal Matrix Composites (MMCs).
Such techniques are Powder Metallurgy (PM), liquid me-
tal infiltration, compocasting, squeeze casting method,
stir casting and spray decomposition metho d [2,3].
Among the fabrication techniques of MMC, stir cast-
ing (for particulate or discontinuous reinforced MMCs) is
generally preferred. Its advantages lie in its simplicity,
flexibility and applicability to large quantity of produc-
tion. It is also attractive because of minimized final cost
of the product. In the stir casting method, there are se-
veral factors that need considerable attention, including
the difficulty of achieving a uniform distribution of the
reinforcement. During these conventional processes, the
major difficulties are improper wetting due to oxidation
which exhibit interface binding between matrix and ce-
ramic phases. Improved wetting must be achieved to ob-
tain a good bond between the matrix and reinforcement.
Other limitations are the distributions of reinforcement,
interfacial reaction between the metal matrix and rein-
forcement, and control of volume fraction shape and size
of reinforcement, often encountered during the fabrica-
Copyright © 2012 SciRes. JMMCE
A. KUMAR ET AL.
tion of Metal Matrix Composites (MMCs). Therefore, all
such factors can affect the expected mechanical proper-
ties of MMCs [4-8].
A new approach has been developed as In-situ pro-
cessing, including SHS (Self-Propagating High Tempera-
ture Synthesis), reactive gas infiltration, liquid-solid or
solid-gas-liquid reactions, XDTM, DIMOX, VLS,
PRIMEXTM [9-11]. In-situ process involve a chemical re-
action resulting in the formation of a very fine, thermo-
dynamically stable, clean surfaces of ceramic rein-
forcement within a metal matrix. The other advantages of
In-situ process are, isotropic in nature, strong chemical
bonding between th e matrix and reinforcement phase, th e
distribution of reinforcement particles within the metal
matrix is homogeneous [12-14]. Therefore, the produced
composite are of better mechanical properties as com-
pared to monolithic materials.
Various types and sizes of reinforcements are used in
matrix of Aluminium like SiC, TiC, Al2O3, B4C, TiB2,
TiN, etc. Among these, TiC is a relatively new reinforce-
ment in metal matrix composites an d has good properties
such as wettability, thermal stability and distribution in
Aluminium metal matrix [15-17].
Present work deals with In-situ fabr ication of Al-4.5%
Cu metal matrix composite with 10 wt% TiC as rein-
forcement by In-situ process. The interfacial reaction
between the elements in composite is very important,
because the load is transferred at the interface and can
affect the mechanical properties of composite. The pro-
duced MMC was evaluated in terms of microstructural
characterization and mechanical properties testing such
as hardness and tensile strength.
2. Experimental Procedure
The raw materials used for the present study for the
preparation of the metal matrix was commercial available
Aluminium ingot (97.95% pure) and Copper (99.98%
pure). The chemical composition of commercial Alu-
minium ingot is shown in Table 1.
The setup used for the In-situ preparation of MMC
through stir-casting route is shown in Figure 1. The high
temperature electric furnace was used for preparation of
Al-4.5%Cu matrix alloy and master alloy o f Al-10%Ti.
In order to produce the composite, both alloys were
melted in graphite crucible and stirred gently at 475 rpm
with mechanical stirrer at 1150˚C temperature with hold-
ing time of 90 minutes. Impurities from the Aluminium
melt or dross was then removed from the surface of mol-
ten metal. The melts were degassed by using hex-
achloroethane (C2Cl6) at 750˚C for removing dissolved
hydrogen gas. The required amount of activated charcoal
powder was weighed and then encapsulated in alu-
minium foil wrappings and added into the molten alloy.
Mechanical stirring was carried out for 2 - 3 minutes. KF
and NaF were added as flux on the surface of liquid me-
tal. The flux reacted with metal alloy and formed layer of
slag that dissolved the oxide film from the liquid surface.
Activated charcoal is assumed to react with Titanium and
formed Titanium carbide (TiC) at 1150˚C temperature
with holding time of 30 minutes. TiC particles were
reinforced into matrix materials by In-situ process. The
resultant slurry was stirred for 1 - 2 min and finally
poured into a metallic mould to get the solidified casting .
The Al-4.5%Cu/10TiC MMC samples for microscopic
examinations were prepared by adopting standard metal-
lographic procedure. Samples were polished using dif-
ferent size of SiC grit papers of 120, 220 , 400, 600, 800,
1000, and 1200, followed by velvet cloth with aluminium
paste. The Keller’s reagent was used for etching with
mixture of 0.5 ml HF, 0.75 ml HCl, 2.5 ml HNO3 and ba-
lance amount of distilled water. The microstructures of
the etched sample were examined using Scanning Elec-
tron Microscope (SEM) as shown in Figure 2. Composi-
tional test of the sample were carried out using En-
ergy-Dispersive X-ray spectroscopy (EDX) and phase
analysis was done using X-Ray Diffraction technique
3. Result and Discussions
3.1. Microstructural Analysis
Figure 2 Shows a typical SEM micrograph of cast In-situ
Table 1. Chemical compositions of commercial aluminium
MaterialsCuFeSiTi Mg Mn Cr NiAl
Compositions 0.70.580.010.04 0.28 0.35 0.04 0.05Balance
Figure 1. Schematic of experime ntal se tup.
Copyright © 2012 SciRes. JMMCE
A. KUMAR ET AL. 1077
Figure 2. SEM micrograph of as cast composite.
Al-4.5%Cu-10%TiC composite. The presence of elements
in metal matrix composite can be observed as peaks of
Al, Cu, Ti and carbon by EDX spectrum shown in the in
Figure 3. The particles of TiC were formed by In-situ
reaction method and were found to be located at Alumi-
num grain boundaries or partly inside the Aluminum
grains. The microanalysis result exhibit the distribution
of TiC as reasonably uniform, though several small clus-
ters of particles are present along with some voids.
Figure 4 presents the XRD spectrums of the as cast
Al-4.5%Cu/10%TiC composite. The dominant phases
observed are Al3Ti, Al4C3, CuAl2 and TiC in the cast
composite. Among these phases, the binary compounds
Al3Ti and Al4C3 are mostly observed in first phase
chemical reactions at lower temperature in In-situ pro-
cess. The reason for synthesis of Al3Ti may be due to ex-
cessive titanium reaction with aluminium. At higher tem-
perature, theses compound react to each other and form
TiC particles in the composite . The binary com-
pound Al4C3 was formed due to excess of carbon present
in molten aluminium. The compound Al4C3 is brittle in
nature and unstable at higher temperatures. Decrease in
retained carbon leads to increase in amount of TiC and
reduction in amount of impurities along the grain boun-
daries. Consequen tly, both tensile and ductility improved
in produced MMCs . The phases identified have
clearly been labeled in Figure 5(a). The optimum molar
ratio of Ti and C is 1:1.3 in composite. Under such con-
dition these binary compound can be reduced to the pro-
duced composite. TiC particles form only when reaction
temperature was more than 1000˚C. TiC particles were
spherical, needle or block in shape with smooth and clear
surface [20-23]. Figure 5(b) shows that the size and
shape of TiC particles formed were from 0.1 µm to 0.8
µm with spherical shape.
3.2. Mechanical Testing
In order to investigate the hardness of as-cast matrix ma-
terials and composites, the samples were tested by using
a standard Vickers hardness testing machine with a py-
ramid indentor of load 5 kg. The load was applied for 15
sec and average of five readings was taken for each spe-
cimen at different locations to circumvent the possible
effects of particle segregation.
The average values of hardness of matrix material and
composite were 61 and 94 respectively as shown in the
Table 2. The TiC particles embedded with matrix mate-
rials affected 35.79% increase in the hardness.
The tensile specimens were prepared according to
ASTM E-8 as shown in the Figure 6. Yield strength and
ultimate strength of matrix and composite material was
tested with universal testing machine. The strain rate was
0.01s–1 during testing of the specimens. For each testing
condition, 3 specimens were subjected to tensile test and
the average of three values was noted. The yield strength
increases from 76 to 87 Mpa and ultimate strength in-
creases from 118 to 147 Mpa after 10% TiC reinforce-
ment in Al-4.5%Cu as shown in Table 2. The investiga-
tion of fracture surface morphology of matrix and com-
posite material specimens was observed by Scanning
Electron Microscope (SEM).
Figure 3. EDX results of Al-.45%Cu/10TiC.
Figure 4. XRD pattern of composite material.
Copyright © 2012 SciRes. JMMCE
A. KUMAR ET AL.
Figure 5. (a) SEM micrograph of the Al-4.5%Cu/10TiC; (b)
SEM micrograph (at higher magnification) of Al-4.5%/
Table 2. Average Hardness and Tensile value of matrix and
Sl. No. Materials Vickers Hardness
( σy (Mpa) )
( σu (Mpa))
1. Al-4.5%Cu 61 76 118
2. Al-4.5%Cu/10%TiC 94 87 147
Figure 6. Schematic of tensile specimen (all dimension in
The fracture surface of dog-bone tensile specimens of
matrix material and TiC reinforced material were ana-
lyzed under Scanning Electron Microscope (SEM) to de-
termine the mode of failure of the material. Typically, all
the specimens exhibited cup-and-cone failure mode which
indicates a ductile fracture mode. The presence of dim-
ples on fracture surface clearly indicates that necking had
occurred prior to matrix fracture. The fractograph of
Al-4.5% Cu matrix material shows a large deep dimple
in fracture surface which exhibited ductile failure as
shown in the Figure 7(a). Al-4.5%Cu/10%TiC compo-
site material observed small dimples on the fracture sur-
face which also revealed the presence of fracture mode to
be ductile one, as shown in Figure 7(b). Some de-
bonded particles are also seen on fracture surface which
proves that relatively strong bonding is present in be-
tween the matrix material and reinforced particles. Fig-
ure 7(c) shows a higher magnified fractograph of Al-
4.5%Cu/10%TiC composite material which observed crack
propagation on fracture surfaces, though this propagation
could no longer propagate and were arrested by rein-
forced particles. The transfer of loads form metal matrix
to particles clearly understands to successfully synthesize
hard TiC particles through In-situ pr ocessing.
Figure 7(a) SEM micrograph of fractured specimen of
Al-4.5%Cu; (b) SEM micrograph of fractured specimen of
Copyright © 2012 SciRes. JMMCE
A. KUMAR ET AL. 1079
In-situ Al-4.5%Cu/10%TiC metal matrix composite was
successfully fabricated using stir casting route. Ti was
added in elemental form and activated charcoal powder
was added in the melt which resulted into the formation
of Titanium Carbide as reinforcement. As the reinforce-
ment phase was formed inside the melt (In-situ process),
the distribution of Titanium Carbide was seen to be more
uniform. The yield, ultimate tensile strength and hardness
were seen to increase by 12.64%, 19.72%, and 35.79%
respectively in the composite material with TiC as rein-
forcement. The fracture surface of tensile sample shows
small dimples indicates ductile fractures. Tensile strength,
fracture surface and hardness of Al-4.5%Cu/10%TiC
MMC fabricated in the present investigation indicated
improvements of material properties.
The authors would like to thank the Department of Me-
chanical and Industrial Engineering. Indian Institute of
Technology, Roorkee for providing the necessary facili-
ties and fund for experiment an d tests
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