In addition to the matrix and reinforcement,
another important thing is the fabrication technique
used today. Powder metallurgy (powder metallurgy)
has several advantages compared to liquid
metallurgy. The temperature used in powder
metallurgy processes can be lower, that is, below the
melting point of the material. Meanwhile, in liquid
metallurgical engineering, high temperatures are
required to reach the melting point of the component
materials (Ramadhonal, 2010).
(Risky, 2019)examined the effect of the addition
of SiC on the properties of hardness and bending
strength as well as the microstructure of aluminium
composites. The studies varied between SiC (0%, 3%,
5%, 9%). The research proves that there is an increase
in the results of the hardness test and bending test
results for each addition of SiC. This proves that SiC
can increase the strength of metal composites.
(Supriyatma et al 2016) examined the Effect of
Magnesium Addition on Hardness, Impact Strength
and Microstructure of Aluminium Alloy (Al-Si)
Using Lost Foam Casting Method. In this study, there
was an increase in the addition of Mg to Al-Si alloys
based on used car alloy wheels using the lost foam
casting method. The hardness number after the
addition of Mg was 109.70 HRL, and before the
addition of Mg was 99.8 HRL. It was concluded that
the increase was 9.9%.
(Triadi, 2022)examined the effect of sintering
temperature and material composition on the
mechanical characteristics of composites made from
waste aluminium and glass using powder metallurgy
methods. This study found that the specimen with the
highest compressive strength value was found at a
sintering temperature of 590 C and a composition of
90:10, which was 235.59 MPa. While the lowest
strength value is 45.11 MPa at a sintering temperature
of 390 C and a composition of 70 :30. The results of
the hardness test showed that the highest hardness
value was obtained in specimens with a composition
of 90: 10 and a sintering temperature of 590 C,
namely 60 HRF, followed by temperatures of 490 C
and 390 C. The same applies to the composition of
other materials, namely the greatest hardness value is
found at the highest sintering temperature.
1.1 Metal Matrix Composite (MMC)
Metal matrix composite (MMC) comes from a
combination of metal-based materials with ceramics.
MMC can also be called a material consisting of a
matrix in the form of metal and its alloys which is
reinforced by reinforcing materials in the form of
continuous fiber, whiskers, or particulate. The
manufacture of metal matrix composites can be done
by several methods, including powder metallurgy,
diffusion bonding, liquid phase sintering, squeeze
infiltration and stir casting.(Risky, 2019).
The reasons why MMC has been attracting attention
for nearly 30 years:
1. The MMC approach in metallurgical processes is
the only way to produce a wide variety of these
composites. So that the resulting product is very
wide (varied). It is only in this way that we can
combine aluminium, copper, magnesium with the
carbide, oxide or nitride phase. Because the above
material has a solubility to carbon, the nitrogen in
the molten metal is too low.
2. MMC also provides significant changes to the
properties of the material, such as resistance to
high temperatures, does not react to chemicals,
good hardness, and wear resistance.
Metal matrix composites can be made by the
casting method or by the powder metallurgy method.
However, the casting method has a problem, namely
it is difficult to make homogeneous composites,
because the reinforcing particles usually settle or float
due to differences in specific gravity.
1.2 Powder Metallurgy
Powder Metallurgy (Powder Metallurgy) is the
process of forming commercial workpieces from
metal where the metal is in the form of a powder, then
the powder is pressed in a mold and heated below the
melting temperature of the powder to form a
workpiece. So that the metal particles coalesce due to
the mass transport mechanism due to atomic diffusion
between the particle surfaces. Powder metallurgy
methods provide precise control over the composition
and use of mixtures that cannot be fabricated by other
processes. As the size is determined by the mold and
finishing touch.
Basic steps in powder metallurgy
(Demasya, 2018):
1. Powder maker.
2. Mixing.
3. Compaction.
4. Sintering.
Figure 1: Compaction Process(Risky, 2019).