K. SANUSI, E. AKINLABI: FRICTION-STIR PROCESSING OF A COMPOSITE ALUMINIUM ALLOY (AA 1050) ...
427–435
FRICTION-STIR PROCESSING OF A COMPOSITE ALUMINIUM
ALLOY (AA 1050) REINFORCED WITH TITANIUM CARBIDE
POWDER
UPORABA ME[ANJA S TRENJEM ZA IZDELAVO KOMPOZITA
ALUMINIJEVE ZLITINE (AA1050), OJA^ANE S TITANOVIM
KARBIDOM V PRAHU
Kazeem Oladele Sanusi, Esther Titilayo Akinlabi
University of Johannesburg, Department of Mechanical Science, Auckland Park Kingsway Campus, Johannesburg 2006, South Africa
sanusik@gmail.com
Prejem rokopisa – received: 2016-01-22; sprejem za objavo – accepted for publication: 2016-05-20
doi:10.17222/mit.2016.021
In this study the friction-stir processing (FSP) technique was applied for the development of surface composites of aluminium
alloy (AA 1050) reinforced with titanium carbide (TiC) powder of particle size range below 60 μm compressed into the groove.
Rotational speeds of 1200 min–1 and 1600 min–1 and the travel rates of (100, 200 and 300) mm/min were used for the process.
This study investigates the effect of processing parameters on the wear-resistance behavior of friction-stir processed Al-TiC
composites. This was achieved through microstructural characterization using optical and scanning electron (SEM) microscopes
equipped with Oxford energy-dispersion spectrometry (EDS) (Tescan), microhardness profiling and wear resistance tests. From
the results, it was found that the processing parameters influenced the distribution of the TiC particles. The microhardness
profiling of the processed samples revealed an increase in the hardness value compared to the parent material. The
wear-resistance test results confirmed the FSP technique enhanced properties in surface engineering.
Keywords: aluminium alloy, friction-stir processing, microhardness, microstructure, surface composite, TiC
V {tudiji je bila uporabljena tehnika me{anja s trenjem (angl. FSP) za razvoj povr{inskih kompozitov iz aluminijeve zlitine (AA
1050), oja~anih s titanovim karbidom (TiC) v prahu, z velikostjo delcev v obmo~ju pod 60 μm, stisnjenih v utor. Pri tem
postopku so bile uporabljene hitrosti vrtenja 1200 min–1 in 1600 min–1 in hitrosti pomikanja (100, 200 in 300) mm/min. [tudija
raziskuje vpliv procesnih parametrov na odpornost kompozitov Al-TiCi proti obrabi s trenjem. Izvedena je bila mikrostrukturna
karakterizacija z uporabo svetlobnega in vrsti~nega elektronskega mikroskopa (SEM), opremljenega z Oxford energijsko
disperzijsko spektrometrijo (EDS) (Tescan), profiliranja mikrotrdote in preizkusa obrabe. Iz rezultatov je bilo ugotovljeno, da so
parametri obdelave vplivali na distribucijo TiC delcev. Profiliranje mikrotrdote na vzorcih je pokazalo, da je vrednost trdote
pove~ana v primerjavi z osnovnim materialom. Rezultati testa odpornosti obrabe so potrdili, da FSP-tehnika izbolj{a lastnosti
povr{ine.
Klju~ne besede: aluminijeve zlitine, tehnika me{anja s trenjem, mikrotrdota, mikrostruktura, povr{inski kompoziti, TiC
1 INTRODUCTION
Friction-stir processing (FSP) is a newly emerging
technology based on the friction-stir welding (FSW)
method that allows the near-surface regions of a material
to be selectively processed and currently used to enhance
the mechanical properties of conventional materials.1
This process has been applied to microstructural modifi-
cations for enhanced mechanical properties through
intense plastic deformation using a non-consumable
rotating tool that causes material mixing and thermal
exposure and results in grain refinement of the material
being processed.2,3 The benefits of the FSP process
include significant microstructural refinement, densifi-
cation, and homogeneity of the processed zone, homo-
genization of precipitates in various aluminium alloys
and composite materials.4–6 Moreover, the severe plastic
deformation (SPD) and material flow in the stirred zone
of the FSP can be utilized to achieve surface or bulk
alloy modification by the mixing of other elements into
the stirred alloys where the stirred material can become a
metal matrix composite or an intermetallic alloy with
much higher hardness and good wear-resistance pro-
perties.7 Applications of the FSP/FSW are widespread
for the aerospace, automotive and the transportation
industries. Research studies have been reported on the
friction-stir process that grain refinement can be
achieved in this way. The microstructure and mechanical
behaviour of lightweight materials subjected to the
FSW/FSP are being studied extensively, which include
the processing of the microstructure amenable to high-
strain-rate superplasticity.8 Y. Kwon et al. produced 1050
aluminium alloy with an ultra-fine grain size through the
friction-stir process (FSP). They studied the influence of
tool rotation speed on the temperature profile, micro-
structure and mechanical properties of the friction-stir
processed zone (FZ) and they concluded that FSP is very
effective in producing an ultra-fine-grained material with
excellent mechanical properties.
Materiali in tehnologije / Materials and technology 51 (2017) 3, 427–435 427
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UDK 621.7.015:669.715:669.295:620.17 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 51(3)427(2017)
Aluminium matrix composites (AMCs) reinforced
with ceramic particles exhibit high strength, high elastic
modulus, and improved resistance to wear, creep and
fatigue, which make them promising structural materials
for aerospace and automobile industries.9 These compo-
sites can suffer a great loss in ductility and toughness
due to the incorporation of non-deformable ceramic
reinforcements, which limits their wide applications to a
certain extent.10,11 However, the nature of the technique
used to fabricate particle-reinforced metal-matrix com-
posites (MMCs) has been shown to have a significant
effect on the product’s mechanical properties and hence
the applications for which it is suitable.12–15 Surface-
modification techniques such as high-energy laser beam,
plasma spraying, cast sinter and electron beam
irradiation have been developed over the past two
decades to fabricate Surface Metal Matrix Composites
(SMMCs).16–19 It has been shown that friction-stir
processing (FSP) can be effectively used to homogenise
the particle distribution in Al-based in-situ composites.
R. Mishra et al.12 confirmed the application of FSP tech-
nology to fabricate AA5083/SiC SMMC. The incor-
poration of SiC particles on the surface was successful
and bonded well with the matrix. Subsequently, they
confirmed FSP as a promising method to fabricate
SMMCs.2 Mahmoud et al. fabricated AA1050/SiC
SMMC, their results showed that the distribution of the
SiC particles became more homogeneous with an
increasing number of passes and with the combination of
tool rotational speed and the processing speed resulted in
the formation of defects, such as voids and tunnels in the
FSP zone.20 E. R. I. Mahmoud et al.20 also fabricated
AA1050/SiC SMMC and assessed the effect of the tool
pin size and profile. From their results, the wear rates of
the samples produced with the flat surface tools were
higher than that of the samples produced with the
round-shaped tools and the samples produced with the
square profile pin yielded a finer distribution of the SiC
particles.21 R. Bauri et al.22 used FSP effectively to
homogenise the particle distribution in Al-based in-situ
composites. The process was employed on the as-cast
composite to uniformly distribute the TiC particles in the
Al matrix. The composite was subjected to single- and
double-pass FSP and its effect on the microstructure and
properties was evaluated. From their results, they
confirmed that a single pass of FSP was enough to break
the particle segregation from the grain boundaries and
improve the distribution and two passes of FSP resulted
in complete homogenization and elimination of casting
defects. The grain size was also refined after each FSP
pass. This led to a significant improvement in the
mechanical properties after FSP. A. Kahrizsangi and S.
Kashani-Bozorg23 works on a mild-steel substrate by the
introduction of nano-sized TiC powder into the stir zone
using four passes of friction stir processing and the TiC
clusters were formed after the first pass. Sequential
break-up of the clusters and refinement of the matrix
grains were caused by subsequent FSP passes. A near-
uniform dispersion of nano-sized TiC particles was
achieved after the fourth pass. A significant improve-
ment in the wear resistance of the nano-composite layer
was observed as compared to that of the as-received
substrate and the enhanced properties are attributed to
the uniform dispersion of hard nano-sized TiC reinforce-
ments in a matrix of ultra-fine dynamically recrystallized
grains. A. Thangarasu et al.10 fabricated TiC particulates
(2 μm) and reinforced them with an aluminium matrix
composite (AMC) using FSP. The powders were
compacted into a groove and a single pass FSP was
carried out using a tool rotational speed of 1600 min–1
and a processing speed of 60 mm/min. They analysed the
microstructure and microhardness of the fabricated AMC
and from their results, revealed a uniform distribution of
TiC particles which were well bonded to the matrix alloy
with an increase in the hardness value of the AMC
compared to that of the matrix alloy. E. Akinlabi et al.3
investigated the effect of the processing parameters on
the wear-resistance behaviour of friction-stir processed
Al-TiC composites. From their findings it was revealed
that an increase in the hardness value, which was a func-
tion of the TiC particles incorporated when compared to
the parent material and the wear resistance property, was
also found to increase as a result of the TiC powder
addition. The right combination of the processing para-
meters was found to improve the wear resistance
property of the composites produced. Kurt et al. incorpo-
rated SiC particles into the commercially pure alumi-
nium to form particulate surface layers by using fric-
tion-stir processing (FSP). The samples were subjected
to the various tool rotating and traverse rates with and
without SiC powders. Microstructural observations were
carried out by employing optical microscopy of the
modified surfaces. Mechanical properties like hardness
and plate bending were investigated. The results showed
that increasing rotating and traverse rate caused a more
uniform distribution of the SiC particles. Uygur studied
commercially pure (CP) aluminium using the friction stir
welding technique (FSW) to weld the specimens. The
welding process was carried out by rotating 1500 min–1
and by moving 200 mm/min. Under a constant friction
force this involved four different shoulder diameters of
(20, 25, 30 and 40) mm. During welding, temperature
measurements were performed using a non-contact laser
thermometer at various parts of the plates from the
welding centre outwards. Microscopic and mechanical
tests were used to characterize the sample.
In this paper, a further research study was conducted
on AA1050 to uniformly distribute the TiC particles into
the Al matrix using friction stir processing. The pro-
duced composites were investigated through the micro-
structural evolution, wear resistance behaviour and the
hardness distribution. The research study is aimed at pro-
viding a better understanding of the materials behaviour
K. O. SANUSI, E. T. AKINLABI: FRICTION-STIR PROCESSING OF A COMPOSITE ALUMINIUM ALLOY (AA 1050) ...
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after FSP using different combinations of rotational
speeds and travel rates.
2 MATERIALS AND METHODS
In this study, aluminium alloys (AA1050) with rec-
tangular elements with dimensions of (200 × 160 × 3)
mm were used for this experiment. The experimental
setup showing the clamping fixture and the backing plate
system is presented in Figure 1. The chemical compo-
sition of the aluminium alloy used is presented in
Table 1. The V-groove of about 5 mm was machined and
filled with TiC powder with the aim of strengthening the
material. Some 99.5 % TiC with a particle size range
below 60 μm ball milled powder with irregular shape
was used. The powder was compressed into the groove
using a pinless tool across the surface of the material and
a second tool, comprising a pin and shoulder, was
plunged into the workpiece after compressing the TiC
powder. The micrograph of the TiC powder used is
shown in Figure 2. The tools were machined from H13
tool steel and hardened to 52 HRC. The workpieces were
securely clamped on a rigid, smooth, mild-steel backing
plate with dimensions of (650 × 265 × 25) mm, to make
the material withstand the significant perpendicular and
lateral forces developed during the friction-stir process.
The weld matrix employed with the processing para-
meters is presented in Table 2. The rotational speeds
employed were 1200 min–1 and 1600 min–1 and the travel
rates were (100, 200 and 300) mm/min, both repre-
senting the low, medium, and high settings, respectively.
Figure 3 shows a schematic drawing of the V-groove
machined into the base metal.
Table 1: Chemical composition of AA1050
Tabela 1: Kemijska sestava zlitine AA1050
Al Si Fe Cu Mn Mg Zn V
AA1050 99.5 0.25 0.4 0.05 0.05 0.05 0.05 0.05
Table 2: Processing-parameters matrix of friction-stir processing
Tabela 2: Matrika procesnih parametrov pri obdelavi me{anja s
trenjem
Designation Spindle speed(min–1)
Travel rate
(mm/min)
FsP 1200_100 1200 100
FsP 1200_200 1200 200
FsP 1200_300 1200 300
FsP 1600_100 1600 100
FsP 1600_200 1600 200
FsP 1600_300 1600 300
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Figure 2: SEM micrograph of the titanium carbide powder
Slika 2: SEM-posnetek prahu titanovega karbida
Figure 1: Experimental set up
Slika 1: Experimentalni sestav
Figure 3: A schematic drawing showing the V-groove machined into
the base metal
Slika 3: Shematski prikaz in posnetek klinastega utora v osnovni
kovini
All the processed samples and the as-received mate-
rials were cut into the required sample sizes with the aid
of the water-jet cutting technique for microstructural
characterization and microhardness measurements. The
processed specimens were examined with a scanning
electron microscope (SEM) equipped with Oxford
energy-dispersion spectrometry (EDS) (Tescan) were
used to characterize the samples. The microhardness
measurements were conducted using a Vickers micro-
hardness tester with a diamond indenter using 300 g load
and a dwell time of 15 s at the surface of the processed
samples and the parent material. The wear tests were
evaluated on both the as-received and processed samples
using a tribometer (CETRUMT200). The wear resistance
test was performed under dry condition using a
ball-on-disk arrangement on both the parent material and
the materials processed by FSP. The material of the ball
is a tungsten carbide of 10 mm diameter and at a load of
25 N with a reciprocating frequency of 20 Hz and for a
2000 m sliding distance.
3 RESULTS AND DISCUSSIONS
3.1 Surface appearance characterisation
Figure 4 shows the upper surface appearances of the
samples processed at a rotational speed of 1200 min–1
and travel rates of 100 min/min and 300 min/min and
Figure 5 shows the appearance of samples processed at a
rotational speed of 1600 min–1 and travel rates of 100
min/min and 300 min/min. From the figures, good
smooth and quality surfaces were observed after the FSP,
the groove is effectively bonded and no defects such as
voids and cracks were observed on the surface. Figure 6
shows the root of sample C at a rotational speed of 1200
min–1 and a travel rate of 300 min/min. The root
indicates that a thorough stirring was achieved during the
FSP.
3.2 Microstructural evolution
Figures 7 and 8 show the SEM micrographs of the
distribution of the TiC particles in the AA 1050 alumi-
nium produced at rotational speeds of 1200 min–1 and
1600 min–1 , respectively. Figure 7 shows that the grains
in the FSP zone of the specimen were refined; this
caused a high plastic strain in the stirred zone in which
K. O. SANUSI, E. T. AKINLABI: FRICTION-STIR PROCESSING OF A COMPOSITE ALUMINIUM ALLOY (AA 1050) ...
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Figure 6: The root of sample C produced at a rotational speed of 1200 min–1 and travel rate of 300 mm/min
Slika 6: Koren vzorca C, obdelanega pri hitrosti vrtenja 1200 min–1 pri hitrosti pomikanja 300 mm/min
Figure 5: Photograph of samples processed at a rotational speed of 1600 min–1 and travel rates of: d)100 mm/min, e) 200 mm/mm and
f) 300 mm/min
Slika 5: Fotografija vzorcev obdelanih pri hitrosti vrtenja 1600 min–1 pri hitrosti pomikanja: d) 100 mm/min, e) 200 mm/mm in f) 300 mm/min
Figure 4: Photograph of samples processed at a rotational speed of 1200 min–1 and travel rates of: a)100 mm/min, b) 200 mm/min and
c) 300 mm/min
Slika 4: Fotografija vzorcev, obdelanih pri vrtilni hitrosti 1200 min–1 in hitrosti pomikanja: a) 100 mm/min, b) 200 mm/min in c) 300 mm/min
severe plastic deformation was introduced into the
workpiece through the rotating pin and shoulder, which
results in a redistribution of the TiC particles. This can
be attributed to the heat generated by the tool rotation
speed and the traverse speed that resulted in lots of
dilution of the TiC and the Al. A homogenous distri-
bution of the TiC particles is essential to attain higher
mechanical properties in the composite of aluminium
alloy (AA 1050) and the TiC. The mechanism of grain
refinement in AA1050 is that of dynamic recrystalli-
zation.22,24 It was observed in Figure 7 that the TiC
particles were clustered together at a rotational speed of
1200 min–1 and a travel rate of 100 min/min compared to
the samples produced at travel rates of 200 mm/min and
300 mm/min. This indicates that when the travel is at a
slower rate, the TiC particles are not well distributed. It
was observed in Figure 8 that the size of the TiC
particles is not uniform throughout the FSP zone. It was
observed that some of the TiC particles were clustered in
the samples produced at a high rotational speed of 1600
rpm. This can be attributed to the elevated temperature
generated by the tool rotation speed and the traverse
speed employed, which is in agreement with the
published literature, as reported in some work by re-
searchers in aluminium matrix composites.25–27 Particles
other than the TiC and aluminium were also observed in
the processed specimens, using energy-dispersive X-ray
spectroscopy (EDS).
3.3 Energy-dispersive X-ray spectroscopy (EDS)
Energy-dispersive X-ray spectroscopy (EDS) analysis
was conducted to evaluate the morphological features of
the debris found in the processed specimens. Figure 9
shows the EDS of the debris of an FSP specimen pro-
cessed at rotational speeds of 1200 min–1 and 1600 min–1.
The EDS pattern, shown in the figures, reveals that some
particles are comprised of elements like Si, C, Fe and
Ag. The presence of these elements indicates that the
debris consist of elements present in the tool as well as
in the backing plate (e.g., Fe, C). The figures also reveals
that the extent of elements like Si, C, Fe and Ag are
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Figure 7: SEM photograph of grains after processing at a rotational speed of 1200 min–1 and travel rates of: a) 100 mm/min, b) 200 mm/min,
c) 300 mm/min
Slika 7: SEM-posnetek zrn po obdelavi s hitrostjo vrtenja 1200 min–1 in hitrostjo pomikanja: a) 100 mm/min, b) 200 mm/min,c) 300 mm/min
Figure 8: SEM photograph of grains after processing at a rotational speed of 1600 min–1 and travel rates of: d) 100 mm/min, e) 200 mm/min,
f) 300 mm/min
Slika 8: SEM-posnetek zrn po obdelavi s hitrostjo vrtenja 1600 min–1 in hitrostjo pomikanja: d) 100 mm/min, e) 200 mm/min, f) 300 mm/min
present in the specimen, which implies that the worn out
particles/debris mainly result from the tools/backing
plate and/or dissociation of the TiC. However, tool-wear
debris is inevitable during FSW/FSP and reported in the
FSP specimen layers in a scattered fashion by A. Kahri-
zsangi and S.vKashani-Bozorg and Y. Wang et. al.23,28
3.4 Hardness profiling
Figures 10 and 11 shows the Vickers microhardness
of friction-stir processed AA1050 reinforced with TiC
powder processed at the rotational speeds of 1200 min–1
and 1600 min–1, respectively, at different travel rates of
(100, 200 and 300) min–1. The microhardness was
measured on the matrices of the parent material and
friction-stir processed materials with the lower dashed
straight horizontal line indicating the homogeneity of the
parent material. The hardness shows a significant
improvement of the friction-stir processed material
compared to the parent metal. The increase in the
hardness can be attributed to the presence of the TiC
particles in the matrix of the composite and the grain
refinement of the matrix. The hardness across the
friction-stir processed zone is not constant and the peak
hardness value was observed at the point where the TiC
was spotted. The average hardness values of the
processed materials and the parent material are shown in
Figure 11. The average hardness value of the parent
materials is 28.9 HV and the average hardness of the
processed materials after using 1200) min–1 and at (100,
200 and 300) mm/min are (41, 36 and 32) HV, respectiv-
ely. The hardness results of the processed materials after
using 1600 min–1 and at (100, 200 and 300) mm/min for
processing were (44, 34 and 32) HV, respectively.
3.5 Ultimate tensile strength
D. Tabor29 has shown that the ratio of ultimate tensile
strength (UTS) to the Vickers hardness is related to the
strain hardening coefficient. The relation between these
parameters was expressed using Equation (1):
UTS
H
C
n
n
n
n
=
⎛
⎝
⎜ ⎞
⎠
⎟ −
−
⎛
⎝
⎜ ⎞
⎠
⎟( )
.
1
125
1
(1)
K. O. SANUSI, E. T. AKINLABI: FRICTION-STIR PROCESSING OF A COMPOSITE ALUMINIUM ALLOY (AA 1050) ...
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Figure 9: EDS of debris of FSP specimen processed at rotational
speed of: a) 1200 min–1 and b) 1600 min–1
Slika 9: EDS-zlomnine iz FSP vzorca, obdelanega s hitrostjo vrtenja:
a) 1200 min–1 in b) 1600 min–1
Figure 11: Vickers microhardness of friction-stir processed AA1050
reinforced with TiC powder processed at the rotational speeds of 1600
min–1 and different travel rates: the lower dashed line shows the parent
material’s condition
Slika 11: Vickers mikrotrdota obdelanega AA1050 z me{anjem s
trenjem, oja~anega s TiC v prahu, obdelanega pri 1600 min–1 in pri
razli~nih hitrostih pomikanja: ni`ja ~rtkana ~rta prikazuje osnovni
material
Figure 10: Vickers microhardness of friction-stir processed AA1050
reinforced with TiC powder processed at the rotational speed of 1200
min–1 and different travel rates: the lower dashed line shows the parent
material’s condition
Slika 10: Vickers mikrotrdota predelanega AA1050 z me{anjem, s
trenjem in oja~anega s TiC v prahu, obdelanega pri hitrosti vrtenja
1200 min–1 in razli~nih hitrostih premika: spodnja ~rtkana ~rta ka`e
pogoje pri izvorni zlitini
Where UTS is the ultimate tensile strength, # is the
Vickers hardness, n is the strain-hardening coefficient,
and C is a constant that has a value of 2.9 for mild steels
and ~3.0 for copper alloys and aluminium. This relation
was further improved by J. R. Cahoon30 in the form of
Equation (2):
UTS
H n n
=
⎛
⎝
⎜ ⎞
⎠
⎟⎛
⎝
⎜ ⎞
⎠
⎟
2 9 0 217. .
(2)
where H is the Vickers hardness and n is the strain-
hardening coefficient.
Using Equation (2), the UTS were calculated and
plotted in Figure 13. From Figure 13 it was observed
that the parent material has a lower ultimate tensile
strength compared to the materials processed by
friction-stir processing reinforced with the TiC powder.
It was also observed that the materials processed using
rotational speeds of 1200 min–1 and 1600 min–1 and a
travel rate of 100 have higher ultimate tensile strengths
compared to the others. The trends in Figure 13 also
correlate with the hardness results in Figure 12.
3.6 Wear-volume losses
The wear-volume loss of the samples after the wear
test is shown in Figure 14 as a function of the process
parameters for loads of 25 N with a sliding distance of
2000 m. It has been shown theoretically that the mass
loss can be estimated using the Archard Equation (3):
V K
SL
H
=
3
(3)
where V is the volume worn away during testing, S is
the total sliding distance, L is the normal load, H is the
hardness of the softer surface, and K is a dimensionless
wear coefficient specific to the sample under test. It is
reasonable to expect from Equation (1) that the
materials after FSP will experience a smaller mass loss
and it shows in Figures 9 to 11 that the samples
processed by FSP have a higher hardness than the parent
material sample, which also shows in Figure 14 that the
samples processed by FSP exhibit a lower mass loss
compared to the parent material. Wear resistance is
usually better for the MMC than the base metal for all
the process parameters. This is due to the fact that the
composite surface layer provides better wear resistance
and it is harder than the base material.
The dimensional wear coefficient, k, is widely used
to compare the wear rates in different classes of mate-
rials and is defined by Equation (4):
K
V
SL
= (4)
The calculation suggests that under a load of 25 N
and at a 2000 m sliding distance, the dimensional wear
coefficient for the samples processed and the parent
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Figure 14: Wear-volume loss of processed samples for different
parameters
Slika 14: Volumske izgube pri obrabi vzorcev, obdelanih z razli~nimi
parametri
Figure 12: Average microhardness of parent material and friction-stir
processed AA1050 reinforced with TiC powder
Slika 12: Povpre~na mikrotrdota osnovnega materiala in AA1050,
oja~anega s TiC v prahu po obdelavi z me{anjem s trenjem
Figure 13: The ultimate tensile strength of parent material and
friction-stir processed AA1050 reinforced with TiC powder
Slika 13: Natezna trdnost osnovnega materiala in AA1050 oja~anega s
TiC, obdelanega z me{anjem s trenjem
material are shown in Table 3. These results confirm the
feasibility of using FSP with larger bulk samples,
especially for the optimization of surface properties such
as the wear-resistance behaviour.
Table 3: Dimensional wear coefficient
Tabela 3: Koeficient dimenzijske obrabe
Designation Dimensional wear coefficient(mm2 N–1)
FsP 1200_100 6.1712 × 10–6
FsP 1200_200 7.6321 × 10–6
FsP 1200_300 8.977 × 10–6
FsP 1600_100 1.378 × 10–5
FsP 1600_200 1.5227 × 10–5
FsP 1600_300 1.580 × 10–5
Parent Material 1.815 × 10–5
4 CONCLUSION
In the present study, FSP was performed on an
aluminium alloy (AA 1050) with TiC powder in order to
investigate the evolving microstructural and mechanical
properties. A surface composite layer was successfully
fabricated on the aluminium sheets and the following
conclusions were drawn from the test outcomes:
• The microstructural evolution of the AA1050 during
FSP showed that the TiC particles were more
uniformly distributed in the AA1050 after FSP using
1200 min–1 and at 100 mm/min, while at a high
rotational speed of 1600 min–1, it was observed that
the TiC particles were clustered in some parts of the
stirred zone after the FSP.
• The hardness tests showed an improvement and an
enhancement on the integrity of the processed
materials due to the improvement in the evolving
microstructure.
• The wear-resistance test results confirm the feasibi-
lity of using FSP for the optimization of surface
properties of the composites produced.
Acknowledgements
The authors gratefully acknowledge the financial
support of the National Research Foundation (NRF)
South Africa, Faculty of Engineering and the Built
Environment, University of Johannesburg, South Africa
and the eNtsa Research Group of Nelson Mandela
Metropolitan University (NMMU), Port Elizabeth, South
Africa, for allowing us to use their facility. The Tertiary
Education Support Programme of ESKOM South Africa
and the University Research Committee (URC), Univer-
sity of Johannesburg, South Africa are acknowledged for
the award of the research funds to support this study.
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