Development and Mechanical Characterisation of Al6061-Al2O3-Graphene Hybrid Metal Matrix Composites

MMC based on aluminium (Al) were produced for light-weight applications especially in aviation and automobile areas. Present paper deals with the fabrication and mechanical performance of AA6061 matrix composites fortified with Al2O3 (alumina) and graphene particulates. Fluid metallurgy method namely stir casting route was employed for fabricating the hybrid composites. Al2O3p and graphene powder are mixed in different weight fractions in which graphene (1 wt. %) particle reinforcement is held consistent and Al2O3 reinforcement is differed freely with 5, 10 and 15 wt. %. Using optical analyser and SEM equipment, microstructural examination is carried out and the result reveals that the graphene and Al2O3 particles prevalently are homogeneously appropriated on the grain limits of Al matrix and Al2O3 particles are disseminated between graphene in the as-cast AA6061 MMC’s. Detailed analysis on investigation of the microstructure and mechanical aspects of Al6061-graphene-Al2O3p composites is presented by following ASTM guidelines; results uncovered that with increment in reinforcement particles, there is an enhancement in the hardness, ultimate strength, yield strength and a decline in the elongation values was however noticed when contrasted with Al6061 alloy. Fractography investigation revealed dimples in unreinforced alloy and the composite.

Influence of Particle Size and Particle Range Distribution on the Microstructure of Al–Mg–Si/PKSA Composite for Amateur Solid Rocket Chamber

The study discusses an overview of small rocket program, development and characterization of locally sourced material at low cost. The aim is to enable the construction of small sounding rocket components for experimental purposes in Nigeria. This paper proposes the utilization of palm kernel shell ash as filler materials in the development, characterization and production of composite material to construct prototype reusable chamber and accessories that will enable it possible for small scientific experiments. To achieve this, particle size and particle range distribution on the microstructure, texture, and mechanical properties of (Al–Mg–Si)/PKSA composites developed by powder metallurgy method were investigated. The access in the 6xxx series of aluminum-magnesium-silicon alloy was investigated for this reason. ImageJ software was used to do particle size analysis professionally and the software was used to calculate the area, mean, standard deviation (SD) and the pixel values. The particle size distribution of big constituent (densification or rather densified solids) particles and small dispersoids possess a finer and slightly elongated grain structure when compared with the unreinforced alloy. The results of the XRD and XRF of all the samples considered showed that Al2O3, SiO2, Mn2O3 and MgO phases were common to all. These hard phases are considered to be responsible for improved mechanical properties and resistance of the composite, while the SEM result showed that the reinforcement was uniformly distributed which further improves the mechanical property of the composite.Keywords: Microstructure, Composite, Rocket, Palm Kernel

Elevated Temperature Tensile Creep Behavior of Aluminum Borate Whisker-Reinforced Aluminum Alloy Composites (ABOw/Al–12Si)

In order to evaluate the elevated temperature creep performance of the ABOw/Al–12Si composite as a prospective piston crown material, the tensile creep behaviors and creep fracture mechanisms have been investigated in the temperatures range from 250 to 400 °C and the stress range from 50 to 230 MPa using a uniaxial tensile creep test. The creep experimental data can be explained by the creep constitutive equation with stress exponents of 4.03–6.02 and an apparent activation energy of 148.75 kJ/mol. The creep resistance of the ABOw/Al–12Si composite is immensely improved by three orders of magnitude, compared with the unreinforced alloy. The analysis of the ABOw/Al–12Si composite creep data revealed that dislocation climb is the main creep deformation mechanism. The values of the threshold stresses are 37.41, 25.85, and 17.36 at elevated temperatures of 300, 350 and 400 °C, respectively. A load transfer model was introduced to interpret the effect of whiskers on the creep rate of this composite. The creep test data are very close to the predicted values of the model. Finally, the fractographs of the specimens were analyzed by Scanning Electron Microscope (SEM), the fracture mechanisms of the composites at different temperatures were investigated. The results showed that the fracture characteristic of the ABOw/Al–12Si composite exhibited a macroscale brittle feature range from 300 to 400 °C, but a microscopically ductile fracture was observed at 400 °C. Additionally, at a low tensile creep temperature (300 °C), the plastic flow capacity of the matrix was poor, and the whisker was easy to crack and fracture. However, during tensile creep at a higher temperature (400 °C), the matrix was so softened that the whiskers were easily pulled out and interfacial debonding appeared.

Morphological and Mechanical Characterization of Al-4032/SiC/GMP Hybrid Composites

The pattern of metal matrix composites can be enhanced by integrating the concept of hybrid composite to produce newer engineering materials. The morphological and mechanical characteristics of Al-4032/SiC/GMP hybrid composites have been investigated. The aluminium alloy (Al-4032) based hybrid composites have been fabricated through the bottom pouring stir casting set up, by reinforcing the silicon carbide (SiC) and granite marble powder ceramic particles as the reinforcement material at various fraction level i.e. 0, 3, 6, 9 weight% in equal proportion. The reinforcement particle size is up to 54 µm. The microstructural characterization of the hybrid composite samples has been carried out using optical microscope, SEM and XRD. The study reveals that the reinforcement hybrid particles (SiC + GMP) are almost uniformly distributed throughout the matrix phase. The mechanical properties (tensile strength, impact strength and microhardness) of the composite samples have been obtained and found to be better than the unreinforced alloy.

Effect of Variation of SiC Reinforcement on Wear Behaviour of AZ91 Alloy Composites

In this investigation, the extensive wear behaviour of materials was studied using SiC reinforced magnesium alloy composites fabricated through the stir casting process. The wear properties of AZ91 alloy composites with a small variation (i.e., 3%, 6%, 9% and 12%) of SiC particulates were evaluated by varying the normal load with sliding velocity and sliding distance. The worn surfaces were examined by scanning electron microscope to predict the different wear mechanisms on the pin while sliding on the hard disk in the dry sliding wear test condition. The microhardness of the SiC reinforced AZ91 composites was found to be more than the un-reinforced AZ91 alloy. Pins tested at load 19.62 N, and 2.6 m/s exhibited a series of short cracks nearly perpendicular to the sliding direction. At higher speed and load, the oxidation and delamination were observed to be fully converted into adhesion wear. Abrasion, oxidation, and delamination wear mechanisms were generally dominant in lower sliding velocity and lower load region, while adhesion and thermal softening/melting were dominant in higher sliding velocity and loads. The wear rate and coefficient of friction of the SiC reinforced composites were lower than that of the unreinforced alloy. This is due to the fact of higher hardness exhibited by the composites. The wear behaviour at the velocity of 1.39 m/s was dominated by oxidation and delamination wear, whereas at the velocity of 2.6 m/s the wear behaviour was dominated by abrasion and adhesion wear. It was also found that the plastic deformation and smearing occurred at higher load and sliding velocity.

Effect of ZrO2 Addition on Microstructure and Mechanical Properties of Al-Zn-Mg Alloy Matrix Composite

Aluminum – based metal matrix composite are widely used in industrial applications compared with conventional and unreinforced alloy. The composite materials usually exhibit a higher strength both at elevated and ambient temperature, as well as wear resistance. The production of composite materials which contain different weight percentage of ZrO2 (0.5, 1.5 and 2.5wt %) by stir casting process. The mechanical properties of the base alloy and composite were evaluated by using tensile and hardness tests. The microstructure inspection by optical microscopy, scanning electron microscope and energy dispersive spectroscopy (EDS) were utilized to study the fracture surface topography. The results represent that the hardness, strength of yield and tensile strength increased with increasing the weight % of ZrO2 to 2.5 % while the elongation decreased. The microstructure inspection by optical microscope shows that the dendrites structure and the particles distribution in matrix without any voids. Furthermore, the grain size refining with the weight percentage of weight reinforcement elevated.

Effect on the Mechanical Properties of Al 7075 Reinforced with SiC and TiC Particles

In the present industrial scenario, Aluminium and its alloy based composites have more importance in the growing fields of engineering. Aluminium reinforced metal matrix composites are broadly speaking desired because it has the excessive strenth along with less weight, hardness, corrosion resistance, fatigue and creep resistance. The Al composites are focused to use in aerospace, automobile and also in structural domain because it gives good strength with less weight. This paper discussed about the mechanical residences of Aluminium 7075 alloy strengthened with SiC and TiC. Stir casting process was utilized for fabrication of composites and composite specimens are subjected to tensile test by using Universal Testing Machine. The composite hardness was tested by using Brinell hardness tester and the Charpy impact tester used for findings the impact strength. An experimental results are compared with unreinforced alloy of Al 7075. Micro structural characterization confirms the particles of reinforcement are distributed to the entire structure of matrix. The experimental result shows the mechanical properties slightly increased by varying wt% of reinforcements in the matrix material. The better tensile strength (252MPa), hardness (83HB) and impact strength (4.6 Joules) is obtained by the composition of 60% wt of Al 7075, 20% wt of TiC and 20 %wt of SiC.

Mathematical modeling and optimization of tribological behaviour of Al 7075 based hybrid nanocomposites

Many industrial applications necessitate lightweight materials that possess better tribological behaviour. Whilst aluminium based nanocomposites are proposed owing to their lightness, their tribological characteristics must be improved which are dominantly influenced by the selection of reinforcements, manufacturing process and heat treatments. In this research, an aluminium hybrid nanocomposite is produced using a novel molten salt processing and subjected to different heat treatments. Their tribological behaviour is assessed under different operating conditions viz. load, sliding velocity and material condition of the pin. Regression models are formulated to predict the tribological behaviour of developed hybrid composite under different heat treatments. The most significant parameter and optimum level for each of these operating parameters are determined using analysis of variance, main and interaction plots and response surface methodology in the end. The integrated approach helps in deciding the optimum parameter setting for the development of nanocomposite with ameliorated tribological behaviour. Under the optimized conditions, the hybrid nanocomposite could able to reduce the wear resistance by about 63% and the coefficient of friction by 18.5% than unreinforced alloy.

Microstructure and Wear Behavior of Nano-TiB2p/2024Al Matrix Composites Fabricated by Laser Direct Energy Deposition With Powder Feeding

The purpose of this study is to investigate the effect of TiB2 content on the microstructure and wear behavior of nano-TiB2p/2024Al composites fabricated by laser direct energy deposition (L-DED). The dry sliding friction and wear behavior was evaluated using a ball-on-disk tribometer by sliding samples against a 6-mm diameter GCr15 (AISI52100) steel ball under applied loads of 2.2 N at room temperature. Microstructural characterization of the as-deposited 2024Al alloy showed the presence of oriented columnar grains. Once 3 wt% TiB2 particles were introduced, the as-deposited microstructure consisted of a mixture of columnar and equiaxed grains. It was found that the addition of TiB2 particles can significantly improve the wear resistance of L-DEDed 2024Al. For instance, the wear-rate of an 8 wt% TiB2p/2024Al matrix composite with full equiaxed grains is almost 20 times lower than that of the unreinforced alloy. A grain morphology-induced wear mechanism for the L-DEDed TiB2p/2024Al composites is proposed and is dominated by mutual oxidation and abrasive wear. The research results are beneficial to understand the wear mechanism of L-DEDed nano-TiB2p/2024Al matrix composites and can also provide theoretical guidance for the selection of TiB2 content.