Magua m pie ta l. ,Al -1 %Cuco mposit e m a teri alreinf o ced with AlO part i c les
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AL-1%CU COMPOSITE MATERIAL REINFORCED  
WITH AL O PARTICLES CHARACTERIZATION  
2
3
1
1,  
2
3
Romero, Maguampi , Gómez, Leonir ,Camero, Sonia y Yepez, William  
1
2
Universidad Nacional Experimental de Guayana, UNEG; Universidad Central de Venezuela, Facultad de  
3
Ingeniería, Escuela de Ingeniería Metalúrgica y Ciencia de los Materiales, Caracas-Venezuela 105 ,  
3
Universidad Nacional Experimental “Antonio José de Sucre” UNEXPO Puerto Ordaz.  
https://orcid.org/0000-0006-1935-6552  
Recibido (03/12/19), Aceptado (18/12/19)  
Abstract: An Alumium-1% Cu composite material reinforced with ceramic particles in proportions  
, 10 and 15 % by weight is processed via powder metallugy by mechanical mixture, the materials  
5
used are industrial manufacturing residual waste. Once mixed, 300 MPa uniaxial compacting process  
cilindrical probes were obtained for each proportions, they were sintered at 530º C for 4 hours. Sintered  
probes microstructure characterization and chemical microanalysis were obtained by Scanning  
Electronic Microscopy/Optical Microscopy and Energy Dispersive Spectrometry (EDS); furthermore,  
compressibility porcentage calculations and microhardness tests were carried out. The results show  
an equiaxial grain microstructure with a high cohesion degree and good reinforcement distribution,  
in the same way a porcentage of 5-10% indicates a better compressibility porcentage in relation to  
the microhardness, which could guarantee a good material performance in future conforming process.  
Palabras Clave: Aluminium, mechanical mixture, composites, residual waste.  
CARACTERIZACIÓN DE UN MATERIAL COMPUESTO  
AL-1%CU, REFORZADO CON PARTÍCULAS DE AL O  
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3
Resumen: Se procesa vía pulvimetalurgia mediante mezcla mecánica un compuesto Al-1%Cu,  
reforzado con partículas cerámicas en proporciones 5, 10 y 15% en peso, los materiales utilizados son  
residuos de procesos de manufactura industrial. Una vez mezclados, se obtuvieron probetas cilíndricas  
por compactado uniaxial a 300 MPa con cada una de las proporciones, fueron sinterizadas a 530 ºC por  
4
horas. La caracterización de la microestructura y los análisis químicos de las probetas sinterizadas  
fueron obtenidas mediante Microscopía Óptica/Microscopía Electrónica de Barrido y microanálisis  
químico por Espectroscopía de Energía Dispersiva (EDS); además, se realizaron los cálculos del  
porcentaje de compresibilidad y ensayos de microdureza. Los resultados revelan una microestructura  
de granos equiaxiales con un alto grado de cohesión y buena distribución del refuerzo, igualmente para  
un porcentaje de 5-10% indica un mejor porcentaje de compresibilidad en relación a la microdureza,  
lo que pudiera garantizar un buen desempeño del material en futuros procesos de conformado.  
Keywords: Aluminio, mezcla mecánica, compuestos, residuos.  
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I. Introduction  
the particles during the mixing process [9], however,  
Metal matrix materials composite (MMCs) began to some authors suggest a single step to ensure better me-  
be studied in depth in the early 70s as a solution to the tallic properties [10]. The aim was to promote a homo-  
demand for better mechanical properties and to achie- geneous distribution of reinforcing particles within the  
ve weight reduction in aerospace and military systems, matrix using a steel container with a suitable seal in a  
group of materials whose properties are custom desig- Ratiotrol Boston Gear roller, achieving a cascade effect  
ned for each application [1].  
in the mixture at a speed of 90 rpm for 4 h, without rea-  
Many efforts have been directed to the optimization ching a properly state of mechanical alloy, which could  
of these materials based on the use of aluminum as ma- be achieved in high energy mills with higher times and  
trix, for its attractive low density, excellent resistance to speeds, taking into account the other variables of the  
corrosion, wide range of alloys, numerous possibilities milling process and by comparing the results obtained  
of heat treatment and a fairly flexible processing [2-4]. by other authors [11].  
The properties of these composite materials depend on  
Then, cold cylindrical compacts of 22 mm in diame-  
the type of reinforcement, form, quantity, distribution ter and 17 mm in height were made, applying a pressure  
of the phases present in the matrix, among others. In the of 300 MPa, using a hydraulic press of max. 50 Tn, loo-  
case of aluminum matrices, oxides, carbides, borides, king for these values to produce a compaction through  
nitrides or intermetallics particles are incorporated, all strong deformation and obtaining simultaneously better  
of them with high mechanical strength, hardness, elastic interfaces contact between the particles more easily in-  
modulus and thermal stability [5-6].  
corporating the hard reinforcing particles. These com-  
Some researchers [7-8], suggest selecting Al2O3 pacts were sintered at 530ºC for 4 h and cooled in the  
particles to achieve an adequate combination of proper- oven until reaching room temperature, using a Naber-  
ties in compounds with aluminum matrix with various therm oven with a maximum capacity of 1280 ºC.  
intermetallics, as well as modify their content and the  
size of the reinforcement.  
The compacts were characterized microstructurally  
by Optical Microscopy (OM), using an image analyzer  
The present study focuses on characterizing a com- Unitron versamet 3 and a Scanning Electron Microsco-  
posite material of Al-1% Cu matrix by weight, reinfor- py (SEM) with chemical microanalysis by EDS, Esem  
ced with ceramic particles, obtained via powder meta- FEI Quanta 200, the metallographic preparation was ca-  
llurgy, specifically through mechanical mixing. The aim rried out with the following steps: roughing ( abrasive  
is to establish the values of density, compaction ratio paper SiC No. 200-600), polishing (alumina 1-0.03μm)  
and microhardness in order to obtain a material that will and attacked with a 0.5% by volume hydrofluoric acid  
guarantee sensitive properties for future forming pro- solution. Likewise for the observation by SEM, the  
cesses. For this purpose, the techniques of Optical Mi- samples were emulsified in ethanol solution, this one  
croscopy (MO), Scanning Electron Microscopy (SEM) is allowed to evaporate and placed in the sample holder  
with chemical microanalysis by Energy Dispersion with double contact carbon tape. In all cases, working  
X-ray Spectroscopy (ESD) were used to reveal the re- conditions were established using a potential of 20 kV  
sulting microstructure.  
and 15 mm distance from the sample.  
Knowing that the density of the samples obtained  
has a great influence on the final mechanical properties  
II. Experimental section  
To achieve the desired composition of the composite of the developed composite material, it was calculated  
material, it was started with aluminum initial powders, applying the rule of the mixtures [12], the densities ne-  
with predominantly elongated morphology and size cessary for the calculation of the percentage of compa-  
between 15-150 μm, copper particles of different mor- tability of the sintered composite. Likewise, the Vickers  
phologies: elongated (L≈10-70 μm), angular (L≈ 10-80 microhardness was determined using a HMV SHIMA-  
μm) and fine globular (D ≈ 1-15 μm), both with purity DZU, for the different conditions of the material appl-  
>
95%. As reinforcement Al2O3 particles with mainly ying a load of 980 mN and a time of 10 s.  
angular morphologies and sizes between 5-75 μm.  
The manufacture of the composite material is done III. Results and discussion  
with a premixture of Aluminum and Copper powders  
The micrograph of the sintered Al-1% Cu compact  
(Al-1% Cu), in a first stage, followed by the Al2O3 matrix, without reinforcing particles obtained by OM is  
particles, in proportions of 5, 10 and 15% by weight; shown in Figure 1a, a microstructure of equiaxed gra-  
using 1% by weight of stearic acid (C8H26O2) as a ins with minimal presence of pores is observed, which  
process control agent (PCA), to avoid agglomeration of shows a good homogeneity in the compaction of the  
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material, coinciding with some researchers [13-14] that  
Al-1% Cu and b-d with Al2O3 particles 5% (b),  
show that in materials obtained via powder metallurgy 10% (c) and 15% (d).  
exists a relationship between compactness and homoge-  
neity of the mixture.  
Attack: 0.5% by volume hydrofluoric acid solution.  
100X  
In the micrographs obtained by SEM shown in Figu-  
In Figures 1 (b-d) micrographs correspond to the  
compacts with Al2O3 particles, in proportions of 5, re 2a, a preferential location of Cu particles in the grain  
0 and 15%, respectively, a microstructure of equiaxed boundaries of the matrix is observed, this is confirmed  
1
grains is observed which shows a good cohesion be- by chemical microanalysis by EDS, coinciding with  
tween the reinforcing particles and the matrix, this mi- other authors [16-17] that admit the presence of phases  
crostructure is mostly observed for a weight ratio of 5% clearly defined in the grain boundaries in precipitation  
reinforcement. However, as the percentage of reinfor- studies in Al-Cu alloys; the empty spaces observed in  
cement increases, a greater dispersion of the particles is the surface are presumed to be produced during the me-  
observed, with a cover microstructure where the defini- tallographic preparation, specifically in the application  
tion of the grain boundaries is lost, giving an appearan- of the chemical attack given the hardness and heteroge-  
ce of agglomeration of the reinforcing particles, this fact neous composition of the oxide particles which was not  
is similarly consistent with results obtained in previous easy to perform, see Figure 2 (a-d).  
investigations [15-16], which coincide in the uniformity  
of the size of the reinforcing particles to avoid agglo-  
merations product of the pressure and energy applied  
during the compaction process, which produces a very  
heterogeneous distribution in the final product and as a  
result a greater presence of pores.  
Spectru  
O%  
Al%  
Cu%  
m
3
8,49  
39,23  
52,28  
Equally it can highlight that the appreciable porosity  
in Figures 1 (b-d) can be influenced by the metallogra-  
phic preparation because the reinforcing particles in this  
case of greater hardness than the matrix, as they are not  
perfectly cohesived, are displaced during the roughing  
and polishing, which can be evidenced by the geometry  
of the pores or empty sites.  
Figure 2a. SEM micrographs with its chemical mi-  
croanalysis point  
by EDS of the sintered compact Al-1% Cu.  
Equally we observe that as the percentage of rein-  
forcement increases the particles regrouping perfectly  
within the microstructure achieving cohesion, located  
in the grain boundaries, this directly proportional to the  
aggregate percentage, besides observing, in the corres-  
Figure 1. OM micrographs of the sintered compacts: ponding chemical composition, the presence of Ele-  
a) Compound Material  
ments such as C, Ca, Si, F and Fe that it is inferred are  
typical of the alumina manufacturing process, without  
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losing of sight of the fact that we are dealing with in- greater areas of contact and union between the particles.  
dustrial waste with very specific chemical compositions The undissolved particles shown in Figure 2 (a-d)  
that could in some way diminish the final properties of where we observe perfectly bright particles with high  
the material developed, See Figure 2 (b-d).  
copper content and angular dark particles of alumina,  
perfectly located in the grain boundaries, even seen in  
Figure 2 (c-d), that when we increase the reinforcing  
content are better defined in the grain boundaries, could  
influence deterioration of the mechanical properties of  
the material and consequently in the density of the ma-  
terial obtained.  
Spectrum  
O%  
Al%  
Si%  
2
26,63  
69,78  
3,59  
Spectrum  
C%  
O%  
52,14  
4,95  
Al%  
47,86  
95,05  
41,22  
Ca%  
1
2
3
-
-
-
-
9,82  
48,61  
0,35  
Figure 2b. SEM micrographs with its chemical m
croanalysis point  
by EDS of the sintered compact Al-1% Cu with 5% Figure 2c. SEM micrographs with its chemical mi-  
Al2O3  
croanalysis point  
by EDS of the sintered compact Al-1% Cu with 10%  
Al2O3  
In the case of study, the needed energy to achieve  
the atomic mobility of the constituent particles of the  
The alumina particles, undissolved, See Figure 2d,  
powders, to achieve contact or union between them is could be embedded in the surface of the aluminum and  
provided by the temperature of the sintering process form agglomerations, which translates into decohesion  
that reaches 580 ºC, representing an 80% of the point particles within the material, in this respect some au-  
of fusion of aluminum considered as valid according to thors [19], determine that the degree of cohesion be-  
previous works [18], who conclude that the ideal sinte- tween the particles is highly dependent on the grinding  
ring temperature is between 70 and 80% of the melting time of the mixed powders, including their size, in our  
temperature, however, it is below 50% of the melting case it could be inferred that the times of mechanical mi-  
point of copper and alumina, particles present in the xing could be low to achieve a maximum homogeneity  
composite material, which could explain the less dis- in the particles besides influencing their sizes which are  
solution of many of these particles located in the gra- quite heterogeneous, that could affect the mechanical  
in boundaries, this suggests to do tests with increases properties of the produced compound.  
in the temperature of the system which could facilitate  
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Despite these characteristics in the particulate ma-  
terial, values of relative densities above 90% and com-  
pactability around 60% were reached, suggesting a  
good cohesion and distribution of the ceramic particles  
in the Al-1% Cu matrix, under the conditions of proces-  
sing determined for the manufacture of the test pieces.  
Spect  
rum  
O%  
F%  
Al%  
Fe%  
Cu%  
1
2
3
4
10,97  
5,21  
50,10  
-
6,97  
6,97  
-
42,86  
16,38  
49,90  
96,19  
0,33  
38,87  
-
-
75,75  
-
-
Table I  
3,28  
0,53  
Density and compactability values  
%
de  
Theoretica Relative  
l Density Density  
Compactability  
Ratiod  
Density  
Reinforce  
(
g/cm3) a  
(
g/cm3) b (g/cm3) c  
Matriz  
2,63  
2,71  
2,73  
2,75  
2,763  
2,822  
2,881  
2,941  
0,952  
0,960  
0,947  
0,935  
0,644  
0,608  
0,632  
0,537  
5%  
10%  
15%  
Determined by volumetric calculation.  
Determined by the rule of mixtures (1)  
Density of compacts / theoretical density  
Determined by the ratio ρ compact / ρ aparent x 100  
An average Vickers microhardness value of the  
4 HV for the matrix was determined, based on eight  
easurements, which was increased with the reinfor-  
Figure 2d. SEM Micrographs with its chemical mi- cement % added, to values of 27, 31 and 33 HV for  
croanalysis point 5, 10 and 15%, respectively as illustrated in the graph  
by EDS of the sintered compact Al-1% Cu with 15% shown in Figure 3. These values suggest a good com-  
Al2O3  
paction of the material despite the characteristics rela-  
ted to size and morphology of the reinforcing particles  
Table I summarizes the values of relative density already described above. These results related to the  
and compactability ratio of the Al-1% Cu matrix with microstructure and hardness are consistent with other  
the composite material with Al2O3 particles at 5, 10 investigations [15-16], which attribute the increase of  
and 15% by weight, we observe that the value of the re- hardness to the agglomerations of particles during the  
lative density for 5% reinforcement increases, however, compaction process, in this case oxide particles whose  
it tends to decrease as we increase the reinforcement hardness are much greater than the hardness of the ma-  
fraction. We also observe that for the greater percentage trix compound.  
of reinforcement (15%) the compactability ratio decrea-  
ses, this behavior can be related to the superficial defor-  
mations generated on the aluminum particles after the  
mixtures and contributed by the morphology and size  
of the reinforcement, which it is corroborated through  
the images by OM and SEM, where it is observed that  
the alumina particles prevent a better cohesion during  
the compaction and sintering process. This diversity of  
shapes and sizes of the particles could cause a harde-  
ning by deformation of the aluminum that affects the  
conformability of the compound [19-20].  
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Magua m pie ta l. ,Al -1T %o l eCnuti cnoo mSp .oysiCt ea mra ab taerllioalSr. eSinimf oucelad cwi ó inth n AumlOé ri cp aardt ei cl lfles j od e aire.  
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Oxford Pergamon Press, pp. 210-212, Noviembre 1989.  
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[
nun composites”. Joumal of Matcrials Processing Tech-  
nology. Vol. 123, pp. 13-17, Abril 2002.  
[4]R. Soma, et al. “PM processing of Al-A12O3 com-  
posites and thcir characterization”. Powder Mctallurgy.  
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[5]J. Ranninger, et al. “Mechanical characterization of  
AA6061 reinforced with ceramic particles through Me-  
chanical Alloying”. EURO PM Munich, pp. 259-264,  
Noviembre 2005.  
[6]L. Da Costa, et al. “Study of the interaction Matrix  
Reinforcement through DSC in a AA2014- Ni3Al par-  
ticulate composite” PM’98: word congress on Powder  
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1
5
[
IV. Conclusions  
It is feasible to develop by means of powder me- (Fe3Al) particles”. Pow. Met. Vol 45, pp. 247-250,  
tallurgy composite materials for manufacturing pro- Mayo 2009.  
cesses using metallic waste. We obtained compacts in [9]L. Valencia. “Obtención y caracterización por vía  
green as resistant enough to be processed and sintered, pulvimetalúrgica de la matriz de aluminio reforzada con  
it was achieving to develop a final composite material partículas intermetálicas de CuAl2 y Cu”. Tesis de Gra-  
with a good relationship between its microstructure and do Doctoral. Universidad del Valle. Santiago de Cali,  
microhardness. The microstructural analysis and the pp. 125-130, Noviembre 2010.  
microhardness values obtained from the composite ma- [10]E. Ruiz, et al. “Influence of blending and particle  
terial Al-1% Cu, with the different reinforcement per- distribution on Base Aluminium MMC’s.” Word con-  
centage of Al2O3 reveal that for reinforcements of 5% gress on Powder Metallurgy. Vol. 5, pp. 146-151, Fe-  
and 10% it was possible to obtain a composite material brero 2010.  
with a better distribution and consolidation of its micro- [11]N. Shoshin, et al. “Preparation and Chtuaetcrization  
constituents which could guarantee a better response in of energetic Al-Mg mechanical alloy powders”. Com-  
future conformation processes. For reinforcing quanti- bustion and Flame. Vol. 128, pp. 259-269, Marzo 2002.  
ties greater than 10%, the percentage of compactability [12]C. Da costa, et al. “Materiales Compuestos de ma-  
decreased, which did not allow to obtain a consolidated triz metálica. I parte. Tipos, Propiedades y Aplicacio-  
material.  
nes”. Revista Metalúrgica Madrid, pp. 179-192, Junio  
000.  
[13]V. Salvador y N. Amigó. “Microstructure and Me-  
2
V. Acknowledgment  
The authors express special thanks to the Metallur- chanical Behaviour of Al-Si-Mg Alloys reinforced with  
gical and Materials Research Institute of the Orinoco Ti-Al Intermetallics”. AMPT Leganes Spain. Vol 3, pp.  
Siderúrgica "Alfredo Maneiro" of Ciudad Guayana, 1499-1508, Septiembre 2001.  
specifically to the department of technology transfer.  
[14]F. Velasco, et al. “Mechanical properties and wear  
behaviour of PM aluminium composite reinforced with  
(Fe3Al) particles”. Pow. Met. Vol 45, pp. 247-250, Fe-  
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