This document discusses the in situ synthesis of titanium carbide (TiC) nanoparticles within an aluminum matrix during mechanical alloying using nanodiamond powders as carbon precursors. The study demonstrates that the optimal combination of materials for synthesis is aluminum (30 g) and TiC (40 g), resulting in nanoparticles averaging around 30 nm, which are uniformly distributed in the matrix. Differential scanning calorimetry shows that the developed composites maintain thermal stability, making them suitable for applications in casting technologies.

1. Accepted Manuscript
In situ synthesis of TiC nano-reinforcements in aluminum matrix composites during
mechanical alloying
Vladimir A. Popov, Manfred Burghammer, Martin Rosenthal, Anton Kotov
PII: S1359-8368(17)34341-X
DOI: 10.1016/j.compositesb.2018.02.023
Reference: JCOMB 5548
To appear in: Composites Part B
Received Date: 15 December 2017
Revised Date: 14 January 2018
Accepted Date: 22 February 2018
Please cite this article as: Popov VA, Burghammer M, Rosenthal M, Kotov A, In situ synthesis of TiC
nano-reinforcements in aluminum matrix composites during mechanical alloying, Composites Part B
(2018), doi: 10.1016/j.compositesb.2018.02.023.
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In situ synthesis of TiC nano-reinforcements in aluminum matrix composites during
mechanical alloying
Vladimir A.Popov1
*, Manfred Burghammer2
, Martin Rosenthal2
, Anton Kotov1
1
National University of Science and Technology “MISIS”, Leninsky prospect, 4, 119049
Moscow, Russia
2
ESRF, 71 avenue des Martyrs, 38000 Grenoble, France
*corresponding author e-mail address: popov58@inbox.ru
Abstract
In this paper the possibility of fabrication of titanium carbide reinforcing nanoparticles inside
an aluminum matrix by in situ synthesis during mechanical alloying will be discussed. The
application of nanodiamond particles as carbon precursor for synthesis allowed obtaining TiC
particles in nanosized form due to the size of initial nanodiamond particle of 4-6 nm. The
developed composites were investigated by scanning electron microscopy, X-ray diffractometry,
and differential scanning calorimetry.
Keywords: A: Metal-matrix composites (MMCs); Particle-reinforcement; B: Microstructures;
D: Electron microscopy
1. Introduction
The advancement of science and technology requires the development of new materials. On
the one hand, modernized materials enhance the quality of various products and increase their
service life, while on the other hand they create new technical solutions that are fundamentally
different when compared to existing ones. Metal matrix composites [1-18] provide a new level of
properties unattainable in conventional non-reinforced metals and alloys. However, composites
with powder-like reinforcing particles still deserve considerable attention. Multiple studies have
been dedicated recently to the development of nanocomposites. e.g., composites with nano-sized
reinforcing particles. However, nano-powders in this application display a number of features,

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such as an increased surface area and high activity of the material, which results in a large
amount of foreign matter and contamination on the surface of the nanoparticles. Contamination
at the interface between the metal matrix and the reinforcing particle is one of the major reasons
preventing a wider application in industry. This is explained by the fact that despite being an
insignificant amount, these contaminations and inclusions considerably reduce the bonding
strength between the composite components.
In casting technologies, contaminations and inclusions on the surface of nanoparticles result
in reduced dampening between the components which, at the very least, causes irregular
distribution of reinforcing particles in the matrix, and more often leads to them being removed
from the melt along with the slag.
To reduce contamination at the interface between the metal matrix and the reinforcing
particle, various methodologies have been developed. A promising approach is the in situ
synthesis of nanoparticles in the matrix. In this case, the synthesized nanoparticles have no
contact with air, and thus no contamination between the reinforcing particle and the metallic
matrix is formed.
Recently, titanium carbide has been generating increased interest due to its good mechanical
characteristics. The literature includes reports on in-situ studies of the synthesis of titanium
carbide reinforcing particles during the mechanical alloying process [11-13]. In the described
processes, titanium and graphite (or soot) particles were used as precursors. The synthesis is
often carried out when annealing granules after mechanical alloying.
The hereby presented work is intended to study the in-situ synthesis of nanoparticles of
titanium carbide in an aluminum matrix during mechanical alloying when using nanodiamond
powders and titanium particles as precursors. The extremely small size of nanodiamond particles
and their exceptional hardness are those characteristics of nanodiamonds (ND) that led to their
choice for the experiment [19-29]. The exceptional hardness and the quantity of nanodiamonds

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results in intensification of the mechanical alloying process, and their small size has a positive
effect upon the size reduction of synthesized titanium carbide particles.
2. Materials, equipment, and methodologies
The composites were fabricated by mechanical alloying [30-34]. In the studies, commercially
available aluminum, titanium and detonation-synthesized nanodiamond powders were used as
initial materials. A technical grade aluminum powder was applied to the matrix, with an initial
particle size of 30-100 µm. As precursors for the synthesis of titanium carbide particles,
technical grade titanium powders were used with a particle size of 100 µm, alongside detonation-
synthesized nanodiamond powders manufactured by Kombinat Elektrohimpribor (FSUE).
Primary nanodiamond particles are near-spherical in shape; in general, they are 4-6 nm in size. A
distinctive feature of nanodiamonds, just like most nanopowders, is that they can combine into
agglomerates reaching up to hundreds of micrometers in size. In terms of nanoparticle bonding
strength, there are primary and secondary (and sometimes tertiary) agglomerates. The strongest
are primary agglomerates. At the start of mechanical alloying, secondary agglomerates
deagglomeration into primary nanoagglomerates of up to 100 nm. A substantial period of time is
required for complete deagglomeration of the agglomerates.
A Retsch PM400 planetary mill with four tightly closed grinding jars was used for
mechanical alloying. Balls of 12 mm in diameter were used as the milling tool. The ratio of ball
weight to the weight of the processed material was 10:1. The rotation velocity of the grinding
jars around the common axis (rotation rate of the carrier) was 300 rpm. The drums were air-
cooled during operation. To prevent overheating, the planetary mill was stopped after every 10
minutes of operation for 5 minutes to cool-down. The processing time was deemed to be the time
when the mill was operating, disregarding the cool-down intervals.
The granules obtained after mechanical alloying were studied using a scanning electron
microscope Helios NanoLab™ 600i DualBeam™ (FEI). Secondary electrons registration mode
was used. For the studies, granules were cut by an ion beam to avoid surface contaminations

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influencing the analysis. The quantitative metallography (determination of reinforcing particle
size) was performed using the AxioVision Release 4.5 software package. Thermal effects
occurring when heating the samples were studied using a differential scanning calorimetry DSC
404 C Pegasus (NETZSCH, Germany). The measurements were conducted in platinum-rhodium
crucibles with aluminum oxide inserts at a rate of 20 °C/min. During the measurement process, a
dynamic inert atmosphere was maintained (argon, 50 ml/min). The XRD analysis was carried out
on a Bruker D8 ADVANCE diffractometer and a DRON-3 diffractometer using CuKα-radiation
in both cases.
3. Results and discussion
For in situ synthesis of TiC particles in the metal matrix via mechanical alloying, it is
necessary to use precursors: titanium and carbon particles. Titanium particles have tens and
hundreds micrometers in size. Graphite and soot consist of particles with similar sizes. Reaction
between titanium and carbon micro-particles leads to formation of TiC micro-particles, basically.
Fig. 1 shows cross sections of several composite granules with TiC reinforcements produced
from graphite and soot precursors.
a b
Fig. 1. Cross sections of composite granules with TiC reinforcements produced from graphite (a)
and soot (b) precursors (SEM images)

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It is possible to obtain reinforcing nano-particle inclusions from in-situ synthesis just based
on mechanical alloying the use of nano-precursors. Nanodiamond powder as carbon precursor
was applied for the investigation.
The total mass of the mixture of initial materials for processing in a single grinding jar during
mechanical alloying was 70g. The weight ratio of titanium to nanodiamonds in each sample
corresponds to the ratio of their atomic weights. The following combinations of initial
components were studied:
1) Al (10 g) + (Ti+ND) (60 g)
2) Al (20 g) + (Ti+ND) (50 g)
3) Al (30 g) + (Ti+ND) (40 g)
4) Al (35 g) + (Ti+ND) (35 g)
5) Al (40 g) + (Ti+ND) (30 g)
6) Al (50 g) + (Ti+ND) (20 g)
During mechanical alloying of mixtures 1 and 2, i.e. “10 g Al + 60 g (Ti+ND)” and “20 g Al
+ 50 g (Ti + ND)”, respectively, the synthesis of titanium carbide particles was extremely
intensive. Fig. 2a shows the X-ray pattern obtained for mixture 1. It can be seen that the titanium
carbide synthesis was fully completed with no initial components left. The titanium carbide
synthesis set in almost immediately after the start of the milling process, e.g., while the major
part of the nanodiamond agglomerates have not yet been crushed. This results in a significant
part of synthesized titanium carbide particles being around 1 µm in size (Fig. 2b). At the same
time, the milling drums heated up significantly leading to damages in the sealing gaskets in some
cases, causing disruption of the process.

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a b
Fig. 2. X-ray diffraction pattern (a) and granule cross section (b – SEM image) of composite
“10 g Al + 60 g (Ti+ND)”
Mixture 3 of initial materials is identified to be the most promising: Al (30 g) + (Ti+ND) (40
g), which is Al – 30g, Ti - 31.98g; nanodiamonds - 8.02g (the following approximate
composition is obtained: 43%wt.Al + 57%wt.TiC). The diffraction pattern of mixture 3 is shown
in Fig. 3a. In this case, the nanodiamond agglomerates are crushed before the synthesis process
sets in. Basically, only the non-agglomerated nanodiamond particles 4-6 nm in size reacted with
titanium during in-situ synthesis of TiC during mechanical alloying. Theoretical evaluation
shows that the size of a titanium carbide nanoparticle obtained from a single nanodiamond
particle is smaller than 10 nm. Fig. 3b shows SEM micrograph of a cross-section of composite
granules of this composition. The cross-section is made by the help of ion beam cutting, which
guarantees the absence of impurities during the manufacturing process. It can be seen that the
titanium carbide particles obtained are of nanosize and are evenly distributed through the matrix
with no defects along the phase boundary. Determining average grain size and computing the
particle size distribution histogram (Fig. 3c) shows that the average size of a reinforcing particle
is 31 nm. Some increase in the average size of the real titanium carbide nanoparticles when

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compared to the theoretically calculated value is explained by the fact that some nanodiamond
nanoagglomerates undergo the synthesis reaction before they have been completely crushed.
a b
c
Fig. 3. Results of study of composite “30 g Al + 40 g (Ti+ND)”: (a) X-ray diffraction pattern;
(b) SEM image of cross section of granule; (c) TiC particle size distribution histogram
The study has shown that applying nanodiamonds results in intensified mechanical alloying,
which leads to the synthesis of titanium carbide, forming nanoparticles in the aluminum matrix.
If the amount of aluminum in the mixture exceeds the optimal composition the synthesis
process is slowed down. With a 35:35 ratio between the aluminum weight and the total weight of
titanium and nanodiamonds, no formation of clear crystalline phases are observed after 6 hours
of treatment (Fig. 4)., apart from the onset of titanium aluminides forming. In this case some of

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the titanium is removed from the TiC synthesis which is undesirable. For an Al: (Ti+ND) ratio
of 50:20, no titanium carbide synthesis is observed, and only titanium aluminides are formed.
Fig. 4. X-ray diffraction pattern from composite “35 g Al + 35 g (Ti+ND)”
The evaluation of X-ray diffraction patterns (Fig. 3a) showed that the size of titanium carbide
crystallites is 18 nm, but as already indicated, the average size of a reinforcing particle was
31 nm. This means that not all titanium carbide nanoparticles are monocrystalline, and some of
them must be crushed into smaller crystallites.
Differential scanning calorimetry (DSC) was applied to determine the temperature stability
of the developed composites being important to verify the general applicability of such
composite materials. Fig. 5 shows the DSC curves obtained for mixture 3.

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a b
Fig. 5. Results of DSC studies of composite “30 g Al + 40 g (Ti+ND)”: (a) initial heating and
cooldown: (b) repeated heating of the same sample and cooldown
The “as milled“ composite granules were subject to 2 subsequent heating and cooling cycles
from 300 C to 900 C using a heating/cooling rate of 20 °C/min in order to appreciate the impact
of the thermal and mechanical history on the thermal stability of the composites. The DSC curve
obtained during the initial heating clearly shows three major peaks: two peaks when heated and
one peak when cooled down. During heating, the first endothermic peak at 630-670°С is caused
by the aluminum matrix melting. To explain the second peak (also endothermic) the following
hypotheses can be suggested. Since the X-ray phase analysis (Fig. 3a) showed only two
crystalline phases (aluminum and titanium carbide) this suggests that during mechanical
alloying, an unstable amorphous phase occurs in the Al-Ti-C system, which is a precursor for
double titanium carbides and aluminides. Since this phase is amorphous, it will be hardly
detected by X-ray analysis. When heated this phase disintegrates into aluminum, titanium
carbide, titanium aluminide Al3Ti and double carbides Ti3AlC2, Ti2AlC. This process sets in at
about 750 °C marked by a minor exothermic peak. The released aluminum melts, which causes
the second endothermic peak to occur. peak occurs corresponding to the aluminum melt
crystallization. During the second heating, the peak caused by the aluminum matrix melting at
630-670°С is significantly increased when compared to the first heating, which supports the

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suggestion that aluminum is liberated during the initial heating (in the second peak
temperature interval). No chemical interaction between the aluminum matrix and titanium
carbide was found. The composite’s primary components are aluminum and titanium carbide.
This means that this composite can be applied in casting technologies without any concern that
undesirable chemical reactions may occur. This application is possible both as master alloy and
an individual material.
4. Conclusion
The presented work shows that in-situ synthesis of titanium carbide nanoparticles in the
aluminum matrix during mechanical alloying is possible when nanodiamonds are used as a
precursor. The following composition of initial materials is identified as the most promising: Al
(30 g) + (Ti+ND) (40 g), which is Al – 30g, Ti - 31.98g; nanodiamonds - 8.02g (the following
approximate composition is obtained: 43%wt.Al + 57%wt.TiC). In this case, the synthesis of
titanium carbide nanoparticles is complete and the average size of particles obtained is around 30
nm. Differential scanning calorimetry showed that the composite developed is stable within a
wide range of temperatures, which permits its application in casting technologies.
Acknowledgements
The research leading to these results has received funding from the Ministry of Education and
Science of Russian Federation under the project number 14.587.21.0030 (identifier
RFMEFI58716X0030). The authors are grateful to A.S.Prosviryakov, B.R.Senatulin,
M.Y.Presniakov and E.V.Shelekhov for assistance in investigations.
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Figure Captions
Fig. 1. Cross sections of composite granules with TiC reinforcements produced from graphite (a)
and soot (b) precursors
Fig. 2. X-ray diffraction pattern (a) and granule cross section of composite “10 g Al + 60 g
(Ti+ND)”
Fig. 3. Results of study of composite “30 g Al + 40 g (Ti+ND)”: (a) X-ray diffraction pattern; (b)
SEM image of cross section of granule; (c) TiC particle size distribution histogram
Fig. 4. X-ray diffraction pattern from composite “35 g Al + 35 g (Ti+ND)”
Fig. 5. Results of DSC studies of composite “30 g Al + 40 g (Ti+ND)”: (a) initial heating and
cooldown: (b) repeated heating of the same sample and cooldown