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The current study mainly focused on evaluating the dry sliding wear performance of centrifugally casted functionally gradient AA6061–8 vol% B4C composite using response surface methodology (RSM). A cylindrical functionally graded material (FGM) component was produced with the combination of stir and horizontal centrifugal casting techniques. Metallographic characterization by scanning electron microscope has confirmed the gradual variation of B4C particles from external to internal periphery of FGM. B4C concentration and microhardness value were found to be maximum in outer and minimum in inner zone. A mathematical model is established for the outer zone of FGM to estimate response-specific wear rate considering applied load, sliding velocity, and sliding distance as wear parameters. Dry sliding wear tests were performed utilizing a pin-on-disk equipment in accordance with the central composite design of experiments. The high determination coefficient (R2 = 0.9981) indicates the derived model's quality of fit. Furthermore, the optimal wear parameter condition was estimated using response optimizer, ensuing a predicted specific wear rate of 1.8051 × 10–5 mm3/N-m. The validation test was conducted under optimum conditions, and the determined specific wear rate value by the experiment was found as 1.8843 × 10–5 mm3/N-m, indicating reasonable accuracy between predicted and experimental specific wear rates. The morphology of worn-out surface for optimized conditions was analyzed with the help of scanning electron microscopy (SEM) images and energy-dispersive spectroscopy (EDS). [ABSTRACT FROM AUTHOR]

The purpose of the study is to make quantitative and qualitative analyses on the Metal Matrix Composite (MMC). The MMC comprises aluminum alloy AA6061 as the matrix element and 5%, 10% and 15% by weight of silicon carbide particulate (SiCp) as the reinforcement material, before and after heat treatment. This investigation compares the mechanical properties and metallurgical characteristics of the MMC with the base material AA6061. In the present investigation, stir casting method is used for preparing samples of MMC. The produced composites were subjected to heat treatment to enhance their hardness. The influence of the weight composition of the reinforcement particles on the mechanical properties of the MMC is analyzed quantitatively. The mechanical properties such as tensile strength, impact strength and hardness were measured for quantitative analysis, while scanning electron microscope is used for qualitative analysis. The temperature of the furnace and the hardening time during the heat treatment process control the hardness exhibited by the composite materials. The percentage composition of reinforcements in the composite materials influences their mechanical properties. Based on the results, optimal material has been suggested for a wide range of applications. The proposed investigation indicates that if the heat treatment increases, then the microhardness of the MMC increases by 13.86%, 18.45% and 30.19%, respectively for 5, 10, and 15% by weight SiCp. It is also observed that the maximum tensile strength of MMC is 329 MPa at 10 % by weight of SiCp. Compared to the base material, it is a 12.5% increase in its tensile strength. Increase in the percentage composition of SiCp to 15wt. % reduced the impact strength by 13%. The scanning microscopy reveals that MMC having 10% by weight of SiCp has a medium-size grain structure. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) are crucial to the progress of composite application areas due to their remarkable mechanical properties. Their usage has expanded into different fields such as the aerospace, automobile, and defense industries. The present study used wrought Al alloy AA6061 as the matrix, while ilmenite (FeTiO3) particles were used as reinforcement at different weight percentages to prepare metal matrix composites. One of the most economical and simple casting routes among the several available fabrication techniques for the preparation of composites is the stir casting method, which was applied in the present investigation to prepare the AMCs. The machinability of the fabricated composites and the surface roughness property after machining were studied to understand the effect of speed and feed during machining. The results showed that an increase in speed decreased the cutting forces and the surface roughness. Meanwhile, an increase in surface roughness was observed with an increase in feed. [ABSTRACT FROM AUTHOR]

Aluminum metal matrix composites (AMMCs) explicitly show better physical and mechanical properties as compared to aluminum alloys and results in a more preferred material for a wide range of applications. The addition of reinforcements embargo AMMCs employment to industry requirements by increasing order of machining complexity. However, it can be machined with a high order of surface integrity by nonconventional approaches like abrasive water jet machining. Hybrid aluminum alloy composites were reinforced by B4C (5-15 vol%) and solid lubricant hBN (15 vol%) particles and fabricated using a liquid metallurgy route. This research article deals with the experimental investigation on the effect of process parameters such as mesh size, abrasive flow rate, water pressure and work traverse speed of abrasive water jet machining on hybrid AA6061-B4C-hBN composites. Water jet pressure and traverse speed have been proved to be the most significant parameters which influenced the responses like kerf taper angle and surface roughness. Increase in reinforcement particles affects both the kerf taper angle and surface roughness. SEM images of the machined surface show that cutting wear mechanism was largely operating in material removal. [ABSTRACT FROM AUTHOR]

This paper presents the investigations on joining 10-mm Al metal matrix composite plates with particles of SiC and BC as reinforcement using friction stir welding (FSW) process. This study majorly focuses on the metallurgical characterizations to explore the microstructural behavior of the welded specimen subjected to constant load of 10 KN, rotational speed of 1000 rpm, and traveling speed of 75 mm/min of the FSW tool. Further, tensile and hardness properties of the welded specimens are investigated and related to the microstructural variations. The results reveal vital information on the distribution pattern of the elements in the Al metal matrix composite (MMC) in the weld region leading to variation in the mechanical strength. The feasibility of joining Al MMC with FSW is also established through this study. [ABSTRACT FROM AUTHOR]

The purpose of this work is to produce an aluminum metal matrix composite with high strength, low weight with good thermal resistance. For preparing metal matrix composite AA6061 is used as matrix and activated carbon is used as reinforcement and it is cast using modified stir casting technique. The reinforcement activated carbon is added in various weight ratios from 2% to 8% of the matrix. The casted metal matrix composites are taken as per ASTM standard by using wire cut process for various tests. Microstructural test like SEM, EDAX, and thermal tests like Fourier Transform infrared spectroscopy and Thermogravimetric tests were taken .From testing results, it is noted that increase in the percentage of activated carbon up to 6%, shows a significant mixing of matrix and reinforcement it is evident in microstructure test result and also shows there is the formation of voids. Thermogravimetric proves the fabricated composite have good thermal resistance by adding activated carbon as reinforcement. [ABSTRACT FROM AUTHOR]

Aluminium alloy (AA6061) is reinforced with fine particulates are produced composite and discussed in this work. The reinforced aluminium alloy hybrid metal matrix composites (HMMCs) with 5 to 25% vol. fractions of Silicon Carbide and Aluminium Oxidereinforcements were created by stir casting technique. The metal to metal wear behavior of these hybrid composite and that of un-reinforced alloy was investigated by pin-on-disc wear testing machine. The optical micrographs in use for the micro structure investigation of the hybrid composite show that the Silicon Carbide and Aluminium Oxideparticulates reinforcement are regularly distributed in the matrix materials. The surfaces of the wear area were analyzed by SEM, which are shown that wear surface of the hybrid composite materials was normally much rougher than that of the non-reinforced alloy [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy (XPS) was used to analyze the composition of films at different deposition parameters of sputtered Al-Ce coatings on AA6061 aluminum alloys. By means of electrochemical impedance spectroscopy (EIS) measurements, the protective character of these coatings was studied for 21 days of exposure in a 3.5 wt% NaCl solution and an attempt was made to establish the relationship between film thickness and chemical composition (Al/Ce, Ce3/Ce4+ ratios) of the surface before and after the electrochemical characterization. XPS studies revealed the presence of the Alo, Al2O3, CeO2 and Ce2O3 compounds, confirming that the sputtered Al-Ce films were deposited in the metallic form and thereafter were superficially oxidized under ambient conditions. The Al–Ce bonds were overlapped with the signal of cerium oxides. The transport phenomena in the oxide film or controlled diffusion process are strongly dependent on the deposition parameters and exposure time in the aggressive medium. It was also found that in the deposited samples at p4P200t300, the film was still present after 21 days of exposure, although with visible cracks and erosion areas; however, the Ce3/Ce4+ ratio almost remained constant before and after the electrochemical characterization, which explained the barrier properties of these samples as compared with others at different deposition parameters. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the influence of the forging process on microstructure, tensile resistance and fracture behaviour of the AA6061/Al2O3/23p composite is presented and discussed. Forging was carried out in an open die, at the temperature of 470°C, with a deformation ratio of 2.5:1 then the specimens were heat treated at the T6 condition. Microstructural characterization and density measurements showed that hot forging did not induce crack of the particle on the AA6061/Al2O3/23p composite and reduced the porosity with respect to the as-cast material. Usually in literature a reduction of the degree of clustering, due to plastic deformation, is reported. On the contrary, probably due to the low deformation ratio applied, no appreciable difference was observed in the degree of particles clustering, before and after forging. The concurrent effect of plastic deformation and high temperature during forging, instead, led to a recrystallization of the aluminium alloy matrix, with a consequent grain refinement. These microstructural modifications induced an improvement in the tensile strength and an increase, from 50% at room temperature to 165% at 300°C, of elongation at failure in the forged composite. [Copyright &y& Elsevier]

Abstract: The objectives of the present study were to assess and to optimize the fatigue behaviour in strain-controlled tests of different ultrafine-grained (UFG) metals and alloys (Cu, Al, AA6061, α-brass) prepared by equal channel angular pressing (ECAP). Quite generally, the UFG materials investigated exhibited shorter fatigue lives in the low-cycle fatigue (LCF) regime than corresponding conventional grain (CG) size specimens. In all cases, the fatigue lives could be enhanced appreciably by a suitable heat treatment following ECAP without, however, paralleling the fatigue lives of the CG specimens. The microstructural reasons for this behaviour are discussed, and a microstructure-based fatigue life model for UFG materials is presented. [Copyright &y& Elsevier]

Abstract: In this paper, the tensile properties and the low-cycle fatigue behavior of the 7005 aluminum alloy reinforced with 10vol% of Al2O3 particles (W7A10A composite) and 6061 aluminum alloy reinforced with 20vol% of Al2O3 particles (W6A20A composite) were studied. The microstructural analyses showed clustering of Al2O3 particles, irregularly shaped and with a non-uniform size. A significant increase of the elastic modulus and tensile strength in the MMCs, respect to the unreinforced alloys, was evidenced by the tensile tests, while the elongation to fracture decreased. The temperature effect on the tensile properties was not relevant up to 150°C, while strength significantly decreased at 250°C, mainly in the composite with the lower content of the ceramic reinforcement. The low-cycle fatigue tests showed no evidence of isotropic hardening or softening for the W7A10A, and a slight cyclic softening for the W6A20A. SEM analyses of the fracture surfaces showed that both the tensile and fatigue fracture was controlled by interfacial decohesion (expecially for the W7A10A composite), fracture of reinforcing particles (mainly for the W6A20A composite), void nucleation and growth. Also the presence of the MgAl2O4 spinel, probably, played a significant role in the mechanisms of failure in the W6A20A composite, by promoting void nucleation at the particles–matrix interfaces, interfacial decohesion, and also failure of the particles. These effects can be responsible of the slight softening observed in the W6A20A, under the low-cycle fatigue conditions. [Copyright &y& Elsevier]