Investigate the mechanical properties of Aluminium Metal Matrix Composite

The objective of this study is to produce metal matrix composites with aluminium as the matrix material and beryl as the reinforcing particles. Given the comparable density of beryl particles to Aluminum-based alloys, it is anticipated that enhancements in strength and ductility properties will lead to increased mechanical and tribological characteristics, including hardness and wear resistance. Extensive research has been conducted on aluminum-based metal matrix composites (MMCs) in the recent past, specifically focusing on the utilisation of ceramic reinforcements such as silicon carbide (SiC), titanium nitride (TiN), Titanium Diboride (TiB2), zirconia (ZrO2), and alumina (Al2O3). Typically, the ceramic particles employed for reinforcement exhibit notable hardness and high density, resulting in enhanced hardness and improved Tribological wear characteristics. Aluminium-based metal matrix composites (AMMC) were produced by including varying concentrations of beryl (3%, 8%, and 13%) through two distinct fabrication methods: the liquid metallurgy vortex route and the powder metallurgy approach. The beryl mineral phase was initially subjected to crushing and mechanical sieving processes to get particle sizes with an average of 50 ± 10 and 100 ± 10 μm. The mechanical qualities, including hardness and tensile strength, were examined using the Brinell hardness machine and the Universal testing equipment.


Introduction
Structural applications often employ structures composed of lightweight metals such as aluminium, magnesium, or titanium due to the matrix's ability to offer compliant support for the reinforcement [1].Cobalt and cobalt-nickel alloy matrices are commonly employed as matrix elements in hightemperature applications [2].The reinforcement material has been integrated into the matrix structure.The physical characteristics of a compound, such as its resistance to wear, coefficient of friction, and thermal conductivity, can be modified through the use of reinforcement for the sole purpose of enhancing the compound's structural integrity [3].There exist two distinct forms of reinforcement, namely continuous reinforcement and discontinuous reinforcement.Isotropic discontinuous metal matrix composites (MMCs) have the characteristic of uniform properties in all directions and can be effectively processed using conventional metalworking methods, including extrusion, forging, and rolling.Discontinuous metal matrix composites (MMCs) have been found to possess versatile applications across several fields [4][5].In addition, it is possible to process them using conventional procedures; nevertheless, the predominant method employed is the utilisation of polycrystalline diamond tooling (PCD).Wires or fibres, such as carbon fibre and silicon carbide, are employed in a consistent manner to enhance structural integrity.The presence of fibres embedded in a matrix in a particular orientation leads to the formation of an anisotropic structure, wherein the alignment of the constituent material influences its strength [6].Boron filament was utilised as a reinforcement material in the initial construction of the first Metal Matrix Composites (MMCs).Whiskers, short threads, or particles are commonly employed as discontinuous reinforcement in a diverse range of applications.Alumina and silicon carbide are commonly encountered reinforcing materials within this particular category [7].
This study examined the mechanical and wear properties of composites made of Al6061 and beryl.The composites were made using the liquid metallurgy (stir cast) process and comprised 2-12 percent beryl particles by weight.In order to compare the Al6061-beryl metal matrix composites to their basic alloys, we tested their tensile and wear characteristics.Based on the results of the experiments, we found: The tensile strength of Al6061-beryl, which contains 10% beryl by weight, increased by 15.38% compared to the base alloy.The amount of beryl particles added had no positive effect on the weight loss caused by sliding wear.When contrasted with the basic alloy, the specific wear rate dropped 8.9% [8].The impact of microwave sintering on the production of aluminium beryl MMCs and published their findings.This study began with commercially available aluminium powder, which had an average particle size of 40.5 m.After the beryl mineral phase was crushed and mechanically sieved, it was possible to examine particles with average diameters of 110, 80, and 65 m.The 20 mm in diameter green pellets were produced by applying a pressure of 15 MPa.The percentage of beryl in the aluminium ranged from 10 to 30 percent by weight.The microwave furnace was heated to temperatures between 500 and 550 degrees Celsius in order to sinter the green pellets.The scientists found that when the volume proportion of beryl particles grew, the hardness values also increased (Figure 1).Strong interfacial bonding between the beryl particle and the aluminium matrix was found in the study [9].The microstructural study demonstrated that the beryl particles were evenly distributed inside the aluminium matrix.The effects of rolling on the microstructure and wear behaviour of hot-rolled Al6067-beryl composites were investigated in the study [10].Stir casting was used to create Al6067-beryl composites with 2, 6, and 10% weight percentages.Across all scenarios, the wear rates of cast composites were found to be higher than those of hot-rolled composites, according to the researchers.Increases in reinforcing content resulted in decreased specific wear rates for both cast and hot-rolled composites.Aluminium beryl MMC bearings were subjected to a finite element study of contact stresses [11].This paper uses finite element modelling (FEM) to assess contact stresses in interference-fitted assemblies.This study examined MMCs manufactured from commercially pure aluminium with different weight percentages of beryl.An appropriate finite element model was created using the ANSYS workbench software to analyse the pattern of contact stresses in the interference assemblies.To replicate the model's properties, a pressure of 100 MPa was applied and the shaft was spun at different speeds.This study used finite element analysis to systematically examine the contact stresses for bronze, Al-SiC MMC, and Al-Beryl MMC bushes.The ANSYS workbench was used to conduct the simulations and analyses.Based on their research, the authors found that Al-beryl MMC bushes could withstand more stress than bronze and Al-SiC MMC bushes.They also found that changing the bush's contact length had no impact on the stress distribution on the contact surface and that shaft speed had no noticeable effect on contact stresses.A great deal of research into metal matrix composites has led to the current work's primary focus: the synthesis of Al-based metal matrix composites with beryl reinforcing particles and powder metallurgy as the sintering method.Furthermore, tribological wear performance and mechanical property evaluations are also under investigation.

Experimental Methodology
Ceramic reinforcing particles such as silicon carbide, titanium nitride, alumina, and aluminium nitride have been the primary focus of metal matrix composite research.Because beryl's density is nearly identical to that of available pure aluminium, this research work considers beryl as a reinforcing particle, but studies on this topic are still in their early stages.This opens up new avenues for investigation into metal matrix composites, as scientists may now test out novel reinforcing elements beyond the standard fare of Aluminum-density alternatives.Beryl, a naturally occurring mineral with the chemical formula Be3Al2(SiO3)6, is a berylliumalumina-silicate. It was used as a reinforcing material in this study.The study's particles have sizes ranging from 30 to 106 micrometres.The material has a hexagonal crystal structure, as shown in Table 2, and its density falls within the range of 2.6-2.8g/mm 3 .Its hardness falls within the range of 7.5 to 8.5 on Mho's hardness scale.The use of beryl as reinforcement provides numerous benefits in academic settings.Firstly, beryl has a significant elevated melting point of around 1400oC.Furthermore, it demonstrates a relatively low refractive index that falls within the range of 1.57 to 1.59.Furthermore, beryl exhibits a comparable density to that of aluminium, measuring around 2.64 g/cc.In addition, beryl exhibits remarkable strength and hardness, measuring roughly 7.5-8.5 on the Mho's hardness scale.Another benefit is that beryl's composition lacks carbon content, which avoids the creation of Al4C3 when composites are synthesised at high temperatures.Finally, it is important to mention that beryl is inherently non-radioactive.

Figure 2. Beryl in conditions of Fine particles
The already compacted green pellets might use some strength enhancement.Tubular forms are maintained in a furnace under an inert environment of 99 percent pure argon gas and heated to 600 degrees Celsius for two hours.In powder form, this aids in densifying the compressed samples.For each sample, a heating rate of 5 o C/min was employed, followed by a holding time of one hour.The melting point of commercially pure aluminium (the basis metal) was kept below the sintering temperature with great care.After being sintered, the samples are cooled to room temperature by gradually lowering their temperature.

Tensile test
Tensile strength values are found to rise as the beryl concentration increases (Table 3).All of the Al-beryl MMC samples had higher hardness values than the one without beryl reinforcing.In comparison to the unreinforced alloy, the alloy that contained 13% beryl demonstrated a 31% improvement.In accordance with the ASTM G99 standard, the samples were ground and examined.

Wear rate
The wear rate exhibited an inverse relationship with the beryl content, as it decreased with its rise.The wear rate of the sample without beryl reinforcement is the greatest among all the composite samples, regardless of the load variation indicated in

Hardness
Table 5 demonstrates a positive correlation between the amount of beryl and the hardness value, indicating that an increase in beryl content leads to an increase in hardness.The sample lacking beryl reinforcement exhibits the lowest level of hardness in comparison to the other composite samples.The hardness of the alloy increased as the beryl percentage increased.It was noted that the alloy with 13% beryl content showed a 22% improvement in hardness compared to the alloy without reinforcement.

Conclusion
Aluminum-based metal matrix composites (MMCs) are the subject of substantial research.Aluminium is enhanced with different reinforcing particles, and its physical, mechanical, and tribological wear properties are examined.The observed phenomenon can be attributed to the relatively low density of beryl, which resulted in the inadvertent extraction of beryl particles during the process of incorporating liquid aluminium, in conjunction with the flux.Furthermore, the inadequate wettability between beryl and the 7075 aluminium matrix has resulted in a limited inclusion of beryl with a significant volume proportion.
• The superior wear resistance properties of the Al-beryl MMCs can be attributed to the significant concentration of beryl present in the material, surpassing that of other MMCs.
• The particles had the highest reported hardness, followed by the interface with rather low values, and the matrix with even lower values.

Table 1 .
Commercial pure Aluminium powder

Table 2 .
Phases present in beryl

Table 3 .
Tensile properties of Al-beryl MMCs

Table 4 .
The wear rate was determined by conducting experiments under conditions of varied time, with a constant load of 20 N and a constant speed of 500 rpm.

Table 4 .
Wear rate values under varying load conditions

Table 5 .
Hardness values of Al-beryl MMCs