Metal Matrix Nanocomposites Research Articles

Investigations on wire electric discharge machining of hybrid nano metal matrix composites (AA6061/SiC/B4C) for industry need based multi-response optimization

The present experimental investigation is aimed at selecting the best suitable machining combination for wire electric discharge machining (WEDM) of AA6061 reinforced with 1.5 wt% SiC and 1.5 wt% B4C ceramic nano particles. The WEDM experiments were planned based on central composite design by considering flow rate (FR) of the dielectric, servo voltage (SV), pulse off time (Toff) and pulse on time (Ton) as the input variables to investigate on material removal rate (MRR) and surface roughness (Ra). The signal to noise (S/N) ratios was used to identify the influencing parameters on maximizing MRR and minimizing Ra. The combination of factors was found as A5-B1-C1-D1 (Ton: 1.35 μs, Toff: 120 μs, SV: 35 V, FR: 4 l min−1) for MRR and A2-B1-C5-D4 (Ton: 1.05 μs, Toff: 120 μs, SV: 75 V, FR: 7 l min−1) for Ra respectively. The output responses were modeled using response surface methodology (RSM) and were used for multi-objective optimization using Pareto optimality approach. The proposed 18 Pareto optimal solutions can be used for job floor applications in industries for optimum machining of this hybrid nano composites. The field emission scanning electron microscopy (FESEM) analysis of the WEDM machined surfaces shows the presence of wider and deeper craters, micro voids and lumps of debris leading to higher material removal rate.

Nanocomposites: a brief review

Nanocomposite material consists out of several phases where at least one, two or three dimensions are in nanometer range. Taking material dimensions down to nanometer level creates phase interfaces which are very important for enhancement of materials properties. The ratio between surface area and volume of reinforced material used during nanocomposites preparation is directly involved in understanding of structure-property relationship. Nanocomposties offer opportunities on completely new scales for solving obstacles ranging from medical, pharmaceutical industry, food packaging, to electronics and energy industry. This paper presents main ideas behind nanocomposites and discusses matrix materials upon which nanocomposites can be divided in three classes; metal matrix, ceramic matrix and polymer matrix nanocomposites. The goal is to explain which raw material and technique is most suited for processing of a particular nanocomposites as well as application, advantages and drawbacks of nanocomposites. Nanotechnology is still in development and current limitations hinder global transition from macro-scale to nano-scale.

Fabrication of Metal Matrix Composite by Laser Metal Deposition-A New Process Approach by Direct Dry Injection of Nanopowders.

Laser Metal Deposition (LMD) offers new perspectives for the fabrication of metal matrix nanocomposites (MMnCs). Current methods to produce MMnCs by LMD systematically involve the premixing of the nanopowders and the micropowders or require in-situ strategies, thereby restricting the possibilities to adjust the nature, content and location of the nano-reinforcement during printing. The objective of this study is to overcome such restrictions and propose a new process approach by direct injection of nanoparticles into a metallic matrix. Alumina (n-Al2O3) nanoparticles were introduced into a titanium matrix by using two different direct dry injection modes in order to locally increase the hardness. Energy dispersive X-ray spectroscopy (EDS) analyses validate the successful incorporation of the n-Al2O3 at chosen locations. Optical and high resolution transmission electron microscopic (HR-TEM) observations as well as X-ray diffraction (XRD) analyses indicate that n-Al2O3 powders are partly or totally dissolved into the Ti melted pool leading to the in-situ formation of a composite consisting of fine α2 lamellar microstructure within a Ti matrix and a solid solution with oxygen. Mechanical tests show a significant increase in hardness with the increase of injected n-Al2O3 amount. A maximum of 620 HV was measured that is almost 4 times higher than the pure LMD-printed Ti structure.

Surface integrity of metal matrix nanocomposite produced by friction stir processing (FSP)

Friction-stir processing is considered a green manufacturing process of surface composite fabrication and surface modification. Surface integrity includes different parameters such as roughness, topography, microhardness, and chemical analysis, which is one of the primary features of FSP. The goal of this research is to evaluate the surface integrity of FSP on aluminum matrix nanocomposite. The main parameter effects, including rotational speed, pass number, and the traverse speed on the surface roughness, surface topography, microhardness, and chemical analysis, were studied compressively. The obtained result revealed that the model of the quadratic polynomial is fitted to predict surface integrity. Furthermore, the results showed that the pass number and rotation speed 45.7% and 21.2%, respectively, have the most impact on surface roughness. The most impact on hardness belonged to traversing speed with 55%. Such a way, energy-dispersive spectroscopy analysis revealed that in the traverse speed 50 mm/min the microhardness achieve 127.24 Vickers.

Mechanical Properties of Aluminium Metal Matrix Nanocomposites Manufactured by Assisted-Flake Powder Thixoforming Process

This study discusses the superior effect of thixoforming process on enhancing the tensile properties of aluminium matrix composite produced using flake metallurgy route. The flake metallurgy process was utilised to manufacture aluminium matrix composites followed by thixoforming process. Microstructural investigations carried out using transmission electron microscope have shown the synergic effect of thixoforming process on rendering uniform distribution of SiC nanoparticles associated with lower porosity content. X-ray diffraction characterisations have revealed the promising effect of uniform dispersion of SiC nanoparticles on restricting the grain growth of aluminium matrix within nanoscale regime (90 nm) even at high semi-solid thixoforming temperatures (575 °C). The achieved results of tensile tests have shown a profound effect of flake metallurgy of aluminium powder through dual speed ball milling. These results are higher than those achieved by low speed and high speed even with higher SiC content. This was attributed to the uniform confinement of SiC nanoparticles within the samples produced using flake-assisted forming process compared to the ones manufactured using ball milling-assisted processes.

Investigations on Machining and Wear Characteristics of Al 7075/Nano-SiC Composites with WEDM

Nanometal matrix composite materials are broadly used around the world in manufacturing industries. It is extremely hard to machine metal matrix nanocomposites by traditional machining techniques. Therefore, nonconventional machining methods are used to eliminate these problems. Wire electric discharge machining (WEDM) reveals a much higher ability for cutting intricate contours with higher accuracy and reliability for nanocomposite materials. In the present investigation, the impacts of WEDM process parameters like gap voltage, pulse-off time, pulse-on time, and the current were examined. Al 7075 reinforced with nano-silicon carbide with average particle dimension of 50 nm is fabricated by employing liquid-state stir casting technique, and machining also was carried out in the WEDM using design of experiments technique. The material removal rate (MRR) and surface roughness (Ra) for various groups of experimentations were investigated. The effects of the weight content of nanoparticle reinforcement on MRR and Ra were explored. In addition, microstructural analytic optical microscope, scanning electron microscope, energy-dispersive X-ray analysis, X-ray diffraction analysis, and wear-behavior assessments were conducted on the fabricated nanocomposite samples, and their outcomes were evaluated. It has been noticed that MRR decreases when the wt% of nano-reinforcement increases and Ra increases.

Investigation of Electromagnetic and Mechanical Stirring Sequence Effects on Production of Magnesium Matrix Nanocomposite

In this article, mechanical and electromagnetic stirring methods were employed in different sequences during the stir casting process in order to fabricate metal matrix nanocomposite. Sequence of stirring methods can affect particle distribution and porosity of the composite and consequently alter microstructural and mechanical properties. To investigate the stirring effects, AZ31B/1.5 vol% nano-Al2O3 composites were produced using different stirring processes. Next, the as-cast billets were hot-extruded at 350 °C using 20:1 extrusion ratio. The results showed that the sequence of the mechanical and electromagnetic stirring methods have considerable effects on porosity, grain size, microhardness, tensile properties, and high cycle fatigue behavior of the composites. The best mechanical and microstructural properties were obtained by the mechanical stirring method followed by the electromagnetic stirring. The samples produced by this method exhibited 44.7% decrease in grain size, 40.8% increase in hardness, 12.3% enhancement in ultimate tensile strength, and 16.5% improvement in maximum elongation, compared to the monolithic AZ31B sample. Additionally, the endurance limit of the composite enhanced about 21% in high cycle fatigue regime. On the other hand, nanocomposite fabricated by mechanical stirring method showed the poorest behavior under cyclic loading.

Bending strength and notched-sample fatigue life of hBN/TiC-reinforced steel 316 L: A numerical and experimental analysis

Mechanical failure under cyclic and dynamic loading has always been a concern in engineering applications. Many different properties can be achieved by adding different materials to the metal matrix nanocomposites. In this study, steel 316 L is selected as the matrix, and the additive materials of titanium carbide and hexagonal boron nitride in 3.5 wt% for each one are added as the reinforcement particles. The samples are fabricated by powder metallurgy, compacted in pressure of 410 MPa, and sintered in temperature of 1375℃ for 4 h. In addition, some pure steel 316 L samples were provided for comparison purposes. Numerical simulation of bending strength and fatigue life of the notched samples were conducted and verified with experimental tests on the mechanical parts. It appeared that the nanocomposite specimens present a higher mechanical reliability relative to the pure 316 L as a result of adding nanoparticles. Steel 316 L S–N curves of the notched samples are also obtained from numerical analysis.

Dynamic behavior of particulate metal matrix nanocomposite plates under low velocity impact

The main purpose of this work is to investigate low velocity impact behavior of metal matrix nanocomposite plates reinforced with silicon carbide nanoscale particles. First, a micromechanical model is proposed to predict the effective mechanical properties of metal matrix nanocomposites. Two features of the nanocomposite microstructure affecting the elastic properties, including agglomerated state of silicon carbide nanoparticles and size factor, are taken into account in the micromechanical simulation. Then, finite element method is used to analyze the time histories of contact force and center deflection of silicon carbide nanoparticle-reinforced metal matrix nanocomposite plates. Several detailed parametric studies are accomplished to explore the influence of volume fraction, diameter and dispersion type of silicon carbide nanoparticles, spherical impactor velocity and diameter, plate dimensions, as well as different boundary conditions on the dynamic response of metal matrix nanocomposite plates. The presented approach accuracy is verified with the available open literature results displaying a clear agreement. The results indicate that adding the silicon carbide nanoparticles into the metal matrix materials leads to a reduction in plate center deflection and an increase in contact force between the plate and projectile. Moreover, it is found that the nanoparticle agglomeration dramatically decreases the contact force and increases the center deflection of metal matrix nanocomposite plates.

Processing and Property Evaluation of Nano Al2O3 Reinforced Copper- 5% Tin Composites for Bearing Applications

Nano technology has fascinated the attention of numerous material scientists and design engineers. The nano scaled particulates incorporation exhibit many attractive and special properties. The inclusion of nano particulates into the copper matrix might augments the hardness, ultimate tensile strength and yield strength significantly increases, maintaining the ductility. In this paper, the nano Al2O3 reinforced copper - 5%tin- metal matrix composites were manufactured by stir casting technique and reinforcement is varied from 0wt. % to 9wt. % in ventures of 3wt. %. The nano composites are characterized in terms of their mechanical and wear properties. Results revealed that, the distribution of nano Al2O3 particulates is fairly uniform in copper - 5%tin metal matrix. As the level of reinforcement increases, hardness, yield strength, ultimate tensile strength, and wear resistance of the copper - 5%tin – nano Al2O3 metal matrix composites increases. The developed nano metal matrix composites may be an alternative material for bearing applications

The effect of B4C and BN nanoparticles on the mechanical and microstructural properties of Al7010 hybrid metal matrix

In the present study, Aluminum 7010 hybrid metal matrix nanocomposites with Boron Carbide (B4C) and Boron Nitride (BN) nanoparticles as reinforcement materials, combined in equal proportions with 0 to 2.5 weight percent (Wt%) of nanoparticles in steps of 0.5 are prepared using ultrasonic assisted stir casting technique. The composites thus obtained are tested for their microhardness, tensile strength and impact strength by using vickers micro hardness tester, universal testing machine and impact testing machine. The microstructural characterization of the composites is carried using scanning electron microscope and x-ray diffractometer. By analyzing the data obtained it was found that the percentage of elongation and impact strength of the composite are reduced with increase in particle reinforcement up to 2 Wt% and thereafter increased. While the tensile strength and microhardness increased with increase in Wt% of B4C and BN particles up to 2 and thereafter decreased.

Investigations on Wire Electric Discharge Machining and Mechanical Behavior of Al 7075/Nano-SiC Composites

In this research work, the impact of WEDM parameters like gap voltage, wire feed, pulse-off time, and pulse-on time on surface roughness (Ra) and MRR (material removal rate) in metal matrix nanocomposites that are composed of Al7075 and nano-silicon carbide (SiC) with the particle dimension of 50 nm is investigated. The aluminum 7075 is reinforced by using nano-SiC with various weight percentages (2.0%, 4.0%, and 6.0 wt%). Magnesium (1.5%) is incorporated to improve the wettability of the MMNCs. The experimentations are studied by means of DOE technique applying L9 OA. The final outcomes were examined using response graphs. And also, the final outcomes are compared with unreinforced aluminum 7075. From the present analysis, it is determined that various blends of WEDM parameters are necessitated in order to accomplish lower Ra and higher MRR for Al7075/SiC nanocomposites. Basically, it is noticed that by increasing wt% of SiC leads to increased Ra and decreased MRR. The outcomes of these investigations are useful for aerospace, automobile industries to select suitable wire EDM parameters to machine MMNCs of Al7075 reinforcement with SiC nanoparticles at different weight portions.

An Overview of the Recent Developments in Metal Matrix Nanocomposites Reinforced by Graphene.

Two-dimensional graphene plateletes with unique mechanical, electrical and thermo-physical properties could attract more attention for their employed as reinforcements in the production of new metal matrix nanocomposites (MMNCs), due to superior characteristics, such as being lightweight, high strength and high performance. Over the last years, due to the rapid advances of nanotechnology, increasing demand for the development of advanced MMNCs for various applications, such as structural engineering and functional device applications, has been generated. The purpose of this work is to review recent research into the development in the powder-based production, property characterization and application of magnesium, aluminum, copper, nickel, titanium and iron matrix nanocomposites reinforced with graphene. These include a comparison between the properties of graphene and another well-known carbonaceous reinforcement (carbon nanotube), following by powder-based processing strategies of MMNCs above, their mechanical and tribological properties and their electrical and thermal conductivities. The effects of graphene distribution in the metal matrices and the types of interfacial bonding are also discussed. Fundamentals and the structure–property relationship of such novel nanocomposites have also been discussed and reported.

Nanoindentation and Scratch Resistance Characteristics of AZ31–WC Nanocomposites

This work examines the effects of WC nanoparticles on nanohardness, elastic modulus and scratch-induced wear behavior of Mg-based metal matrix nanocomposites. Ultrasonic vibrator-equipped stir casting furnace is used to fabricate Mg–WC nanocomposites. Scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX) and X-ray diffraction (XRD) are employed to conduct the characterizations of base alloy and Mg–WC nanocomposites. Vickers microhardness tester is used to obtain the microhardness values of the fabricated materials. Nanoindentation tests are performed to find the effect of wt.% of WC on the mechanical properties, i.e., nanohardness and elastic modulus. Nanohardness and elastic modulus present nearly 122% and 169.37% increments, respectively, compared to the base alloy when only 2[Formula: see text]wt.% of WC is present as reinforcement. Scratch tests are performed to find the effects of wt.% of WC and applied load on the scratch-induced wear and coefficient of friction (CoF) of the base alloy and Mg–WC nanocomposites. Wear volume also decreases continuously with increase in the weight percentage of WC in magnesium alloy. The COFs of nanocomposites are almost constant but they are inclined to increase with the increase in wt.% of WC. Finally, SEM micrographs of scratch grooves are analyzed to find the wear mechanisms. Abrasive wear mechanism is found to be the dominant one regarding the scratch of Mg–WC nanocomposites.

Combination of Mechanical and Electromagnetic Stirring to Distribute Nano-Sized Al2O3 Particles in Magnesium Matrix Composite

In this article, a novel stirring method has been developed for producing metal matrix nanocomposites, in which two different stirring methods, i.e. mechanical and electromagnetic stirrings, have been used simultaneously. Mechanical stirring might not be sufficient enough to break nano-agglomerations properly. Moreover, this method makes some unwanted porosities and gas entrapments in the composites. On the other hand, the electromagnetic stirring as a sort of body force (with no considerable shear stresses) could be used up to solidification decreasing the dendritic microstructures, gas entrapments, and undesirable agglomerations and impurities. Applying these both stirring methods simultaneously as an electromagnetic-mechanical stirring method, the distribution of reinforcing nanoparticles throughout the matrix phase would be more desirable due to better stirring conditions. In addition, since it is a simple and applicable approach, it can be used for mass production. Magnesium/Al2O3 nanocomposite with volume fractions of 0.5, 1.0, and 1.5% have been fabricated accordingly and then hot-extruded at 350°C using 20 : 1 extrusion ratio. According to the scanning electron microscopy (SEM) results, the nanoparticles have an appropriate distribution in the matrix. Also, comparing the results of microstructural evaluation and Vickers microhardness, tension and compression tests, it was observed that the grain size was decreased and the hardness and yield stress (in both tension and compression tests) were improved by adding more nanoparticles to magnesium matrix.

Recent Studies on the Fabrication of Magnesium Based Metal Matrix Nano-Composites by Using Ultrasonic Stir Casting Technique - A Review

This paper presents the recent studies on the fabrication of magnesium based metal matrix nanocomposites (MMMC) by using ultrasonic assisted stir casting technique. The pure metal and alloys, due to their limited mechanical properties are not suitable for various engineering applications. It has been observed that the addition of suitable reinforcements into metallic matrix improves the specific strength, ultimate tensile strength, porosity and wear properties as compared to the conventional and monolithic engineering materials for aerospace and automotive applications. The effects of ultrasonic vibrations and the resulting uniform dispersion of reinforcements on the mechanical and tribological properties of magnesium based MMCs are specifically highlighted in this paper.

Experimental optimization of mechanical properties of Al7010/B4C/BN hybrid metal matrix nanocomposites using Taguchi technique

The composite material properties largely dependent on the processing methods and the parameters employed during their manufacturing. In the present study, the effect of B4C and BN nanoparticles on tensile strength and microhardness of Al7010 hybrid metal matrix nanocomposite is investigated. The composite is prepared using ultrasonic assisted stir casting technique, and the effect of processing parameters like weight percentage of particles, stirrer speed, stirring time and temperature on ultimate tensile strength and microhardness are optimized using Analysis of Variance technique. The experiments are planned using Taguchi design of experiment based on the L25 orthogonal array. In all the input parameters, the wt% of B4C and BN is most significant on ultimate tensile strength and microhardness followed by other parameters. Further, the verification of optimal experimental results the confirmation tests was conducted and also a percentage error is found.

In-situ molten salt reaction and incorporation of small (10 nm) TiC nanoparticles into Al

Metal matrix nanocomposites (MMNCs) with nanoparticles in a metal matrix are important for widespread applications. Smaller nanoparticles are preferred for a better strengthening effect. However, it is extremely difficult to control the size of nanoparticles in MMNCs through a solidification process. In this study, a novel in-situ molten salt reaction and incorporation method is presented for the fabrication of Al–TiC nanocomposites. The size of the TiC nanoparticles is readily controlled to approximately 11 nm. The mechanical properties are enhanced by the incorporation of TiC nanoparticles. This novel method could potentially be applied to different material systems for high-performance MMNCs.

Multiscale analysis of the low-velocity impact behavior of ceramic nanoparticle-reinforced metal matrix nanocomposite beams by micromechanics and finite element approaches

An efficient multiscale analysis is proposed to investigate the dynamic behavior of metal matrix nanocomposite beams reinforced by SiC nanoparticles under low-velocity impact loads. First, an analytical micromechanics model is developed to obtain the effective elastic properties of ceramic nanoparticle-reinforced metal matrix nanocomposite, and then the finite element method is used to predict the dynamic response of beams made of this nanocomposite material. Two important microstructural features, including size effect and agglomeration of nanoscale particles, are incorporated into the micromechanical analysis. The present simulation results for the elastic modulus and low-velocity impact response show good agreement with previously published results. The effects of volume percent, diameter and dispersion type of ceramic nanoparticles, geometrical features and boundary conditions of nanostructure, velocity and size of projectile on the contact force, and center deflection time histories of metal matrix nanocomposite beams are extensively examined. Analysis shows that homogenously distributed SiC nanoparticles into the metal matrix nanocomposites can obviously increase the nanostructure/projectile contact force and decrease both the beam center deflection and impact duration which is due to the enhancement of elastic properties. However, the ceramic nanoparticle agglomeration has an effect on the decrease of contact force and the increase of both the center deflection and impact duration. Also, it is concluded that decreasing nanoparticle size can increase the contact force and decrease the beam center deflection.

Development and characterization of nanoparticle metal matrix composites: (Al 2024-SiC np)

Composite materials get an importance in value as an advance materials such as automotive, aerospace, aircraft, defense, medical, marine, sports, recreation and various engineering applications due to their high strength-to- weight ratio, good cast ability and better tribological properties. Al-base 2024 alloy reinforced with SiC micron and nano particles were developed using stir casting technique due to low cast, ease in fabrication, recyclability and isotropic characteristics. The development of Aluminum metal matrix nano composites (AMMNCs) is most considered material for high temperature applications because of their excellent mechanical properties, increase performance and weight saving for more reduction of fuel consumption. The results indicate that Al–SiC composite has improved physical and mechanical properties such as tensile strength, charpy impact strength, brinell hardness, density and porosity percentage. Samples with micron particles and nano particles were developed to compare the properties of both. Microstructures of the samples were studied by means of x-ray Diffraction and Scanning Electron Microscopy. The elemental composition was also analyzed through Energy Dispersive Spectroscopy. It was found that composites of Al–SiC have better and improved physical properties in nano dimensions.