chips through press moulding and pre-sintering and finally forging. In the final stage, material parameters were optimized for
improving physical and mechanical properties of these composites [3, 7, 9–15].
In this study, a typical low cost but high performance metal matrix composite was designed by using recycled aluminum
chips (Alumix-123) as matrix material as fine γ-alumina particles main reinforcement element Cu and Mo as secondary
reinforcement element. For the characterization of this composite, Static compression test drop weight (impact) test and also
nano wear and nano creep tests have been carried out. Chemical and microstructural analyses, the internal structure of the
material was analyzed in detail with Scanning Electron Microscope (SEM).
3.2 Experimental Conditions
In the frame of a common research project, an alternative low cost aluminium matrix composite (AMCs) was designed from
the fresh scrap recycled chips of the aluminium series of Alumix-123 given by aeronautic company. After atomization process
of the fresh scarp were premixed by using high energy milling in a planetary ball mill during 1 h and doped with copper/γ
Alumina (Al 2 O 3 ). The final composition was homogenized by ball milling during the 4 hours. For obtaining a homogenous
mixture with fast wettability of the reinforcements to the matrix, pure nano aluminium (<5 wt %) powder was added in the
mixture. Final composition was given in the Table 3.1 with the chemical composition of Alumix-123 (Table 3.2).
Microstructural analyses were done by means of scanning electron microscope (SEM). The dispersion of reinforcement
particles in the matrix and interface at matrix/reinforcements was also evaluated.
Micro hardness tests (HV 0.1 ) have been made on the polished and etched specimens. The micro hardness values obtained
for two different manufacturing processes were found for Sintering, “Sinter + Forging” and presented in the Table 3.3 with
Æ10–20% accuracy for all of the manufacturing processing techniques respectively.
All the density measurements of the specimens were carried out by using Archimedes method. These values change
between 2.90 and 3.35 Æ 05% accuracy respectively.
Quasi-static compression tests have been carried out in a Zwick mechanical test system at strain rate of 1 mm/min 3–4
cylindrical specimens (H/D ! 1.5) was used during the mechanical tests for each manufacturing processing. Again,
3P-Bending tests have also been carried out on the same mechanical test system.
Low velocity impact (drop weight) tests have been carried out on the drop to evaluate dynamic test results.
After sintering and/or sintered forging, all of the cylindrical specimens were tested for the machinability at low cutting
speed with low cutting force to eliminate certain damage on the surface of the specimens such as work hardening or the
damage on the cutting tool (point angle of cutting tool, θ ¼ 130
, feeding rate: 165 mm/min an cutting rate: 10 m/min).
Finally, nano wear and nano creep tests have been carried out by nano indentation under two different normal loads (20 and
50 mN) applied over a linear wear track of 500 and 1000 μm for 50 cycles. A conical tip with a 90
cone angle was used for
this damage. One cycle is defined as a pass and return over the track. The speed of the tip during wear tests was 50 μm/s.
A total of 10 wear tests were performed for each sample. Modulus and Nano hardness measurements have been calculated
from these tests during the unload stage of the nanoindentation. These tests were applied on the two types of specimens;
sintering and sinter+forging.
Again Creep tests using a nano-indenter were performed on the two compositions manufactured to see the time dependent
behaviour. On each sample 25 indents were performed on a 5 Â 5 grid with a Berkovich indenter. The indents were spaced
50 μm along the 5-indent side and 75 μm along the 4-indent side. The load was increased at a rate of 1 mN/s to the max load
Table 3.1 Composition of the composites prepared in two groups (wt. %)
Composition name
Matrix alumix-123
γ-Al 2 O 3
Cu
Mo
SnO 2
Zn-St
ALO
Balance
10
4
2
<1
2
Table 3.2 Chemical composition of scrap Alumix-123 (wt. %)
Element
Al
Cu
Mg
Si
Fe
Mn
wt. %
Balance
4.55
0.5
0.80
0.11
<0.01
Table 3.3 Measurements of
the microhardness values of
the composites
Composition name
Micro hardness values, HV 0.1 (at interface only)
ALO (only sintering)
395 Æ À12
ALO (sintered forging)
445 Æ À15
10
F. Gatamorta et al.
improving physical and mechanical properties of these composites [3, 7, 9–15].
In this study, a typical low cost but high performance metal matrix composite was designed by using recycled aluminum
chips (Alumix-123) as matrix material as fine γ-alumina particles main reinforcement element Cu and Mo as secondary
reinforcement element. For the characterization of this composite, Static compression test drop weight (impact) test and also
nano wear and nano creep tests have been carried out. Chemical and microstructural analyses, the internal structure of the
material was analyzed in detail with Scanning Electron Microscope (SEM).
3.2 Experimental Conditions
In the frame of a common research project, an alternative low cost aluminium matrix composite (AMCs) was designed from
the fresh scrap recycled chips of the aluminium series of Alumix-123 given by aeronautic company. After atomization process
of the fresh scarp were premixed by using high energy milling in a planetary ball mill during 1 h and doped with copper/γ
Alumina (Al 2 O 3 ). The final composition was homogenized by ball milling during the 4 hours. For obtaining a homogenous
mixture with fast wettability of the reinforcements to the matrix, pure nano aluminium (<5 wt %) powder was added in the
mixture. Final composition was given in the Table 3.1 with the chemical composition of Alumix-123 (Table 3.2).
Microstructural analyses were done by means of scanning electron microscope (SEM). The dispersion of reinforcement
particles in the matrix and interface at matrix/reinforcements was also evaluated.
Micro hardness tests (HV 0.1 ) have been made on the polished and etched specimens. The micro hardness values obtained
for two different manufacturing processes were found for Sintering, “Sinter + Forging” and presented in the Table 3.3 with
Æ10–20% accuracy for all of the manufacturing processing techniques respectively.
All the density measurements of the specimens were carried out by using Archimedes method. These values change
between 2.90 and 3.35 Æ 05% accuracy respectively.
Quasi-static compression tests have been carried out in a Zwick mechanical test system at strain rate of 1 mm/min 3–4
cylindrical specimens (H/D ! 1.5) was used during the mechanical tests for each manufacturing processing. Again,
3P-Bending tests have also been carried out on the same mechanical test system.
Low velocity impact (drop weight) tests have been carried out on the drop to evaluate dynamic test results.
After sintering and/or sintered forging, all of the cylindrical specimens were tested for the machinability at low cutting
speed with low cutting force to eliminate certain damage on the surface of the specimens such as work hardening or the
damage on the cutting tool (point angle of cutting tool, θ ¼ 130
, feeding rate: 165 mm/min an cutting rate: 10 m/min).
Finally, nano wear and nano creep tests have been carried out by nano indentation under two different normal loads (20 and
50 mN) applied over a linear wear track of 500 and 1000 μm for 50 cycles. A conical tip with a 90
cone angle was used for
this damage. One cycle is defined as a pass and return over the track. The speed of the tip during wear tests was 50 μm/s.
A total of 10 wear tests were performed for each sample. Modulus and Nano hardness measurements have been calculated
from these tests during the unload stage of the nanoindentation. These tests were applied on the two types of specimens;
sintering and sinter+forging.
Again Creep tests using a nano-indenter were performed on the two compositions manufactured to see the time dependent
behaviour. On each sample 25 indents were performed on a 5 Â 5 grid with a Berkovich indenter. The indents were spaced
50 μm along the 5-indent side and 75 μm along the 4-indent side. The load was increased at a rate of 1 mN/s to the max load
Table 3.1 Composition of the composites prepared in two groups (wt. %)
Composition name
Matrix alumix-123
γ-Al 2 O 3
Cu
Mo
SnO 2
Zn-St
ALO
Balance
10
4
2
<1
2
Table 3.2 Chemical composition of scrap Alumix-123 (wt. %)
Element
Al
Cu
Mg
Si
Fe
Mn
wt. %
Balance
4.55
0.5
0.80
0.11
<0.01
Table 3.3 Measurements of
the microhardness values of
the composites
Composition name
Micro hardness values, HV 0.1 (at interface only)
ALO (only sintering)
395 Æ À12
ALO (sintered forging)
445 Æ À15
10
F. Gatamorta et al.