Fabrication Of Metal Matrix Composites Research Articles

Improvement of Mechanical Properties of 2024 AA by Reinforcing Yttrium and Processing Through Spark Plasma Sintering

The need for developing new methods to fabricate metal matrix composites is a never-ending process, which drove to the development of more facilitated fabricating methods like field-assisted sintering, etc. The main objective of the present experimental study is to develop aluminium 2024 alloy-based metal matrix composites by very little amounts of yttrium reinforcement through field-assisted sintering also called as spark plasma sintering (SPS) and to analyse the relationship between the mechanical properties and corresponding microstructure. Composite samples consisting of aluminium 2024 alloy matrix and yttrium reinforcement, starting from 0.1 to 0.5% by weight, are developed through SPS. Computerized Vickers testing machine is used to determine the hardness of the composite samples. The metallurgical characterization of the composite samples is assessed by optical microscopy, scanning electron microscopy and X-ray diffraction. To compare the influence of yttrium on the composite samples developed, pure 2024 aluminium alloy sample is also sintered. It is found that an optimum amount of yttrium reinforcement (0.3 wt%) creates favourable conditions for strengthening mechanisms to achieve peak properties. Then the properties tend to decrease gradually when yttrium content is increased beyond 0.3% by weight. The highest hardness, ultimate tensile strength and yield strength are found to be 114 HV, 388 and 343 MPa, respectively, with 18.4% elongation in the composite reinforced with 0.3 wt% yttrium. The mechanical properties are in close agreement with the microstructures and grain sizes. High density and improved tensile properties are achieved in the present composites developed through spark plasma sintering.

Selective laser melting of metal matrix composites: Feedstock powder preparation by electroless plating

The objective of this work is to investigate the feasibility to use electroless plating as a feedstock powder production method for additive manufacturing of metal matrix composites (MMCs). MMCs are of importance because of their improved properties compared with existing metallic alloys for additive manufacturing. However, the current powder processing methods (e.g., high-energy ball milling) are difficult to incorporate a high fraction of nanoparticles with a homogeneous dispersion. Electroless plating is proposed to produce MMC powder in this work. Ni/Al2O3 composite powder with a high fraction of Al2O3 nanoparticles was successfully produced using a Ni electroless plating bath containing Al2O3 nanopowder. X-ray diffraction analysis was performed on the prepared powders, showing both Ni and Al2O3 phases as designed. Scanning electron microscopy (SEM) characterization showed the Ni and Al2O3 phases were uniformly distributed in the powder. The Ni/Al2O3 powder was then laser melted into tracks to investigate the effects of process parameters using a commercial selective laser melting (SLM) system. SEM showed stable tracks were achieved under a wide range of process parameters. Both Ni and Al2O3 phases were identified in the melted tracks, possessing a hierarchical micro/nano-structure. The SLM behavior demonstrated the feasibility of electroless plating for producing MMC feedstock powder.

Inconel 625/TiB2 Metal Matrix Composites by Direct Laser Deposition

This work presents results in the field of synthesis of new metal matrix composites with matrix NiTi and particles TiB2, and their use as additives to fabricate metal matrix composites based on the Inconel 625 alloy. NiTi-TB2 powders were obtained using self-propagating high-temperature synthesis. Composite NiTi-TiB2 particles were spheroidized on a high-frequency induction plasmatron. Composite NiTi-TB2 particles were mixed with metallic Inconel 625 powder with particle sizes of 50–150 µm. We used direct laser deposition by means of mixture of powders to grow samples with different contents of ceramics in the metal matrix. The process of direct laser deposition during the experiment was investigated. We have determined the peculiarities of the formation of the structure in metal matrix composites with different contents of titanium diboride. We have demonstrated the possibility of using Direct Laser Deposition (DLD) for fabricating items from ceramic metal materials. We have determined promising fields of further research for the purpose of obtaining efficient metal matrix composites using additive manufacturing technologies.

Laser cladding of iron-based erosion resistant metal matrix composites

Erosion greatly reduces the service life of slurry handling equipment. Applying an erosion-resistant coating on equipment has been widely used to protect components from erosion. In this study, vanadium carbide (VC), titanium carbide (TiC), and tungsten carbide (WC) were blended with AISI 420 stainless steel (SS) powders, respectively, to fabricate metal matrix composites (MMCs) coatings on mild steel A36 by using a high power direct diode laser. The slurry erosion test was conducted at three eroding angles, 30°, 45°, and 90°, by using an abrasive waterjet to evaluate the erosion performance of the fabricated MMCs. The results showed that the resistance of 420 SS to erosion was increased at the impingement angles of 30° and 45° after adding the carbides. At 90° impingement angle, the addition of VC and TiC improved the erosion resistance of 420 SS. In contrast, the WC deteriorated the erosion resistance of 420 SS. In addition, the VC/TiC reinforced coatings had an erosion behavior of ductile material. The maximum erosion occurred at an angle of 45°. In contrast, the WC reinforced coating exhibited the erosive characteristics of brittle material, and the maximum erosion occurred at an angle of 90°. It was found that for all coatings, the VC reinforced coating exhibited the best anti-erosive performance at all impingement angles.

Selective Laser Melting to Manufacture “In Situ” Metal Matrix Composites: A Review

After a brief introduction on selective laser melting (SLM) and “ex situ” manufacture of metal matrix composites (MMCs), this paper reviews the capacities and benefits of SLM to activate and control various “in situ” reactions during fabrication of 3D parts. It introduces several systems (such as Al/Fe2O3, AlSi10Mg/SiC, Al/ZnO, Ti/C, Ti/SiC, Ti/Si3N4, Ti/Mo2C, Fe/SiC, etc.) used to manufacture Al‐based, Ti‐based, and steel‐based “in situ” MMCs. Then, it illustrates the novel microstructural characteristics of these SLM‐made “in situ” MMCs for different cases, as they may appear from nano‐particles to nano‐whiskers and dendritic reinforcements homogeneously distributed in a metal matrix. It also focuses on SLM associated “in situ” mechanisms, explaining how an “in situ” reaction propagates based on “decomposition, diffusion, and reformation” and how the growth mechanisms turn into different morphologies such as rounded particles, whiskers, or polygonal block shapes. The influence of various SLM parameters (such as energy density, laser power/speed, powder layer thickness, and the size of initial powder particles) and the SLM “in situ” challenges are also discussed.

Effect of thermomechanical treatment on properties of an extruded Al-3.0Cu-1.2Mg/SiCp composite

Thermomechanical processing determines the practical applications of metal–matrix composites (MMCs) by contributing to the interrelationship between their microstructure and properties. In this study, we investigate the changes in Al-3.0Cu-1.2Mg/SiCp (40 vol%) caused by the tension applied at high temperatures and strain rates. The study shows the microstructural changes and mechanical characteristics resulting from the cold/warm and hot rolling of the extruded material. It is observed that hot rolling has a favorable effect on the restoration of the defects formed in parts of the extruded bar. The microstructural characteristics of the composite related to the deformation-induced redistribution of the secondary inclusions in the matrix and fracture of the reinforcement particles are shown. High-temperature uniaxial tensile testing of the studied composite conducted under high strain rates (10−1 and 10−2 s−1) indicates an increase in the ductility. The decrease in the stress of the tested samples is attributed to the refined grains in the matrix after the thermomechanical processing. The testing of the given material provides the stress–strain relationships, which indirectly assist in ranking the relative formabilities of the differently processed sheets of the MMCs with a high-volume fraction of the reinforcement particles. The proposed approach may be considered for the near net-shaped manufacturing of MMCs with high wear resistance and low thermal expansion coefficients.

Experimental determination of threshold pressure and permeability based on equation-solving method for liquid metal infiltration processes

Abstract A new method for determining two key parameters (threshold pressure and permeability) for fabricating metal matrix composites was proposed based on the equation-solving method. An infiltration experimental device was devised to measure the infiltration behavior precisely with controllable infiltration velocity. Two experiments with alloy Pb-Sn infiltrating into Al2O3 preform were conducted independently under two different pressures so as to get two different infiltration curves. Two sets of coefficients which are functions of threshold pressure and permeability can be obtained through curve fitting method. By solving the two-variable equation set, two unknown variables were determined. It is shown that the determined threshold pressure and permeability are very close to the calculated ones and are also verified by another independent infiltration experiment. The proposed method is also feasible to determine the key infiltration parameters for other metal matrix composite systems.

Novel method for additive manufacturing of metal-matrix composite by thermal decomposition of salts

Very limited Additive Manufacturing (AM) processes have been developed for production of Metal Matrix Composites (MMCs) reinforced by ceramic. Most of these processes use different mixing techniques to mix metal and ceramic powder particles in order to be used in an existing AM process such as Selective Laser Melting (SLM) process. The current AM techniques for MMCs fabrication have limitations due to material mixing and the AM process limitations itself. This paper introduces a novel AM method for fabrication of MMCs by Thermal Decomposition of Salts (TDS). In this method inorganic salts are printed on metal powder bed to fabricate green part. The green part undergoes bulk sintering. During bulk sintering the printed inorganic salts are decomposed to fine ceramic particles to form MMC. This process is capable of generating MMC structures with uniformly distributed and dispersed ultra-fine ceramic particles in the metal matrix with less limitations and lower cost compared to other existing AM techniques. In this paper, bronze-alumina MMC was fabricated and studied by the TDS process to validate the proposed process. It was also shown that the TDS process can be used to fabricate other types of MMCs besides bronze-alumina due to the nature of the process. Design of Experiments methodology was used to study and model the effects of sintering parameters on the properties of the bronze-alumina fabricated by the TDS process. Due to MMCs unique properties combined with AM benefits, this novel method will be of great interest to various industries such as aerospace applications.

Studies on Wear Behaviour of Aluminium 6061Alloy Reinforced with B4C & Mica Particulates Hybrid Metal Matrix Composite

Hybrid Metal matrix composites are commonly used in Aerospace, Automobile industries because of its light weight, High tensile strength, high resistance to wear and improved specific strength. This is mainly due to improved mechanical and tribological properties like strength, stiffness, abrasion, impact resistance and wears resistance. In the present scenario, a lot of research activities were on automobile. This paper direct the researchers and engineer towards suitable selection of materials by its properties in the relevant area and various techniques involved in fabrication of metal matrix composites, predominantly on the liquid state metal processing method. In this work Al6061, Boron carbide, mica and hybrid Aluminium metal matrix composites are fabricated using Stir casting Techniques with varying mass fraction of mica 3%, 4%, 5% incorporated into the alloy, Sustaining the mass fraction of boron carbide as 10% for all proportions. Mica and B4C ceramic particles were incorporated into Al 6061 alloy by stir-casting method. In Stir casting method of composite materials synthesis, a dispersed phase (ceramic particles, short fibers) is mixed with a molten metal matrix by means of mechanical stirring. The samples were studied using scanning electron microscope (SEM) one of the most useful instrument for future research to know its microstructure. This study emphasize on the dry siding wear behaviour of aluminium reinforced with 3%,4%,5% mica and constant quantity of 10% boron carbide hybrid composite using a pin on disc. Wear performance of the hybrid composites were evaluated over a different load ranges and at different sliding velocities.

In situ formation of metal matrix composites using binder jet additive manufacturing (3D printing)

Simplifying the manufacturing of metal matrix composites (MMCs) will allow for their wider use in applications that require lower density, higher strength, and high wear resistance when compared to traditional metals. An in-situ method of MMC formation is proposed, using a binder jet additive manufacturing (BJ-AM) process with only Inconel 625 powder and a carbon-containing binder. Carbide formation occurs at elevated temperatures during sintering by combining Cr, Mo and Nb alloying elements in Inconel 625 and carbon from the binder. The core-shell morphology and composition of the final MMC is tuned by controlling the quantity of carbon in the system during the sintering step.

Microstructure, mechanical and corrosion properties of electron-beam-melted and plasma-transferred arc-welded WCP/NiBSi metal matrix composites

As one of the new additive manufacturing processes, electron beam melting (EBM) has seen its promising potential in the fabrication of metal matrix composites (MMCs) components with complex geometries. In this work, WCP/NiBSi MMCs were fabricated by EBM and plasma-transferred arc welding (PTAW) for a comparative study. The microstructures of both samples were examined using a scanning electron microscope (SEM) equipped with an electron backscattered diffraction (EBSD) detector. The macrohardness was tested using a Rockwell hardness method (Type C), while the microhardness was measured using different loadings (0.5–1.0 N) based on different phases. The anti-abrasion performance was tested as per the ASTM G105 standard. The corrosion behavior of the MMCs was also assessed by potentiodynamic polarization. The results indicate that the EBM bulk and the PTAW cladding MMCs exhibit different microstructures due to the different local solidification conditions. This is believed to lead to the varied mechanical properties and corrosion resistance of the MMCs, and the possible mechanisms were also discussed.

Influence of Substrate Characteristics on Single Ti Splat Bonding to Ceramic Substrates by Cold Spray

The cold spray technique may be used to fabricate metal matrix composites and to metallize ceramics. Both applications involve the creation of metal/ceramic interfaces, which are well researched for other processes but not nearly as much for cold spray. Here, the effect of ceramic substrate composition and surface roughness on adhesion strength of metallic splats is investigated. Splat adhesion testing was performed on Ti splats deposited on Al2O3 substrates with varying average reduced peak height roughness (Rpk) values. Ti splats sprayed onto Al2O3 with the lowest surface roughness had a higher bond strength (305 ± 87 MPa) than splats deposited on the higher surface roughness Al2O3 (237 ± 47 MPa). Failed interfaces revealed that the bonding mechanism for substrates with higher surface roughness is predominantly mechanical interlocking. Adhesion to the Al2O3 substrate with low surface roughness is predominantly along the periphery of the particle where jetting occurs. Splat adhesion testing was also performed on Ti splats deposited on SiC. Ti splats had a significantly higher bond strength to all Al2O3 substrates than to SiC. Posttest observations of SiC substrates showed little evidence of bonding. Several rebounded or detached splats left traces of Ti along the periphery of the impacted particle.

Microstructure, mechanical and electrical characterization of zirconia reinforced copper based surface composite by friction stir processing

Friction stir processing (FSP) has been established as a solid state technique for fabrication of metal matrix composites (MMCs). In the present investigation, FSP was used to disperse zirconia in copper to obtain copper matrix composite (CMC). For fabrication, a groove of known dimension was machined on to the surface of the copper plate (6 mm thick) and compactly filled with zirconia. After closing the groove with a pinless tool, it was processed with same tool material which had pin. The microstructural evaluation was carried by optical and scanning electron microscope (SEM). Observed micrograph confirmed uniform dispersion of zirconia in the copper matrix. The stir zone (SZ) of the fabricated composite displayed equiaxed and fine grain structure. Mechanical properties of the composite were assessed by microhardness and tensile test. The hardness of the fabricated composite in SZ improved significantly as compared to as received copper. Grain size reduction and uniform dispersion of zirconia contributed to the improvement in hardness. The tensile strength and electrical conductivity of the fabricated composite were found to be less as compared to as received copper. The post-assessment of the tensile specimen showed a reduction in ductility. The decreased electrical conductivity of the composite was ascribed to more scattering of electrons due to increased grain boundaries and non-conductive nature of zirconia.

A Review on Fabrication and Characteristics of Metal Matrix Composites Fabricated By Stir Casting

Need of new materials is always important in industries, better mechanical properties and lower in cost are the main parameters which attracts everyone to develop a new material. This need arises in the form of composite materials. This paper reviews about the composites, their existence, fabrication by stir casting and the characterization of metal matrix composites. Different fabrication techniques were mentioned which can be used for the manufacturing of metal matrix composites but specially focused on stir casting. Uses of stir caste in the various researches are shown in this paper and which gives us better idea to understand various parameters for stir caste like stirrer speed, melting temperature, spindle speed and percentage of reinforcement. Characterization of a metal is always important to describe its properties and which is described with different testing. It explains the revised property of metal matrix composites and that shows it is far better than the parent metal.

Additive manufacturing of metal matrix composites via nanofunctionalization

Abstract

A stir casting system for drawdown of light particles in manufacturing of metal matrix composites

An extensive set of experiments was carried out to examine the effects of impeller types, impeller locations (submergence), solid volume fraction, and baffle configuration on the drawdown efficiency. Flow simulations in a turbulent regime were also performed to investigate the flow patterns, spatial homogeneity (using the mean age distribution), and particle drawdown mechanisms (using a particle level simulation with the discrete phase model). A combination of two casting impellers (a helical impeller near the top and a radial one near the bottom) with two half-baffles was determined to be the optimal configuration for complete drawdown with enhanced particle distribution, while avoiding air entrainment and lowering the impeller speed. Hydrodynamic mechanisms leading to superior drawdown and dispersion performance of the optimal design are discussed with the formation of free surface swirling, turbulence strength, roles of half baffles and helical/radial impellers on the flow and particle motions.

Influence of Nano Al<sub>2</sub>O<sub>3</sub> Particles on Morphology and Microstructure of Cu-Al<sub>2</sub>O<sub>3</sub> Composite Coating by Jet Electrodeposition

Jet electrodeposition process is a very promising method in fabricating metal matrix composites reinforced with ceramic particles. In use of this method, insoluble particles suspended in an electrolytic bath are impinged onto and embedded in a growing metal layer. This paper is focused on the investigations of the copper matrix nanocomposite coatings with hard Al2O3 nanoparticles, electrochemically deposited from jet-circulated baths on 304 stainless steel substrate. The Cu-Al2O3 composite coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The effects of electrolyte jet velocity, current density, addition amount of Al2O3 in the electrolyte were analyzed on the microstructure change, surface morphology change as well as codeposited content of Al2O3 particles in the composite coating. It was found that increasing content of Al2O3 particles in electrolyte may improve composite coating surface morphology and increase the practical current density by exerting impingement effect on the cathode deposit surface, till excessive Al2O3 e.g.20g/L particles was added. Besides, appropriate amount of nanoparticles in the electrolyte also could offer grain refinement by providing nanocrystalline sized between 30~60 nm with current density in the range of 100~500 A/dm2.

Joining and fabrication of metal matrix composites by friction stir welding/processing

Herein, friction stir welding (FSW) of metal matrix composites (MMCs) with different combinations of the reinforcement and the metal matrix is highlighted with a brief introduction into recent efforts that have been used to fabricate MMCs by FSW. As a solid state joining technique, FSW consumes significantly lower energy than conventional fusion welding processes. In addition to properly selecting the process parameters, the mechanical properties of the FSW joints of MMCs are closely related with the refinement and homogeneous distribution of reinforcements in the stir zone. The fatigue and fracture properties of MMCs may be enhanced or aggravated by FSW, depending on the combination of the reinforcement and the metal matrix. For FSW of MMCs, the selection of the tool material can also be a critical issue; the presence of hard reinforcements may increase the rate of tool wear. Macro-and microstructural phenomena for MMCs during FSW depend on the material flow due to plasticization and the behavior of the reinforcements. Even though FSW are generally expected to induce a homogeneous distribution of reinforcements in the stir zone (SZ), it can be difficult to obtain a homogeneous distribution of reinforcements in the SZ depending on the combination of the reinforcement and the metal matrix. The existence of reinforcements naturally affects the microstructure of the joint and can even induce the formation of intermetallics/complex phases in the joint. This review provides a general understanding of the joining or in-situ fabrication of MMCs using solid-state friction stirring.

Studies of ZA-27 / Red Mud Metal Matrix Composites with respect to Corrosion Properties

Conventional monolithic materials have boundaries in achieving good properties like strength, stiffness, toughness and density. To overcome these weaknesses and to meet the ever increasing demand of modern day technology, composites are most auspicious materials of recent interest. Metal matrix composites are most successful materials used for recent works in the industry. Metal matrix composites own significantly improved properties including high tensile strength, toughness, hardness, low density and good wear resistance compared to alloys or any other metal. They also exhibit increased corrosion resistance. There has been an increasing demand in composites containing low density and low cost reinforcements. In this studies popular alloy of nineties ZA-27 is chosen as matrix and red mud particulates which is obtained as a waste in the aluminium manufacturing industries is selected as reinforcement. Liquid melt metallurgy technique using vortex method is chosen for the manufacture of metal matrix composites. Reinforcement content added to matrix was 2 percent 4 percent and 6 percent. Matrix alloy was also casted in the same way for comparison. Microstructures of the composites and matrix alloy are taken by scanning electron microscope technique after machining. Static weight loss corrosion test and potentiodynamic polarization techniques test using potentiostat were conducted in different concentrations of sodium chloride solutions. Specimens for the tests mentioned already are machined from the castings according to ASTM standards. Corrosion rates were calculated after knowing the weight loss in static weight loss corrosion test. Elico company make Potentiostat / Galvanostat model CL95 was used for the determination of corrosion current and corrosion rate. In all the tests the corrosion current was found to decrease from matrix alloy to 6 percent composite. Corrosion rate was also to be decreased from matrix alloy to 6 percent composite. Hence metal matrix composites made up of ZA-27 as matrix and red mud as reinforcement are more suitable for marine applications and automobile applications in place of matrix alloy.

Manufacturing and technological challenges in Stir casting of metal matrix composites– A Review

A “composite” is when two or more different materials are combined together to create a superior and unique material. This is an extremely broad definition that holds true for all composites, however, more recently the term “composite” describes reinforced plastics. This paper presents a study on the composites, production technologies related to metal matrix composites exclusively stir casting. Various processes of manufacturing metal matrix composites and how metal matrix composites are manufactured using stir casting process was discussed in this paper. Many processes like metal injection moulding,friction stir process, mechanical alloying,squeeze casting technology, continuous binder-powder coating etc. are used by the researchers for manufacturing metal matrix composites. Out of these processes stir casting process is very cost effective and simple. Researchers are doing lot of work in the field of production technologies of MMC which has brought down their cost to an acceptable level compared to those processed by powder metallurgy and spray casting process. Properties of these metal matrix composite materials depend upon many processing parameters of stir casting process like stirring temperature, stirring speed, stirring time, preheating time,etc. and selection of matrix and reinforcements. This paper presents an overview of stir casting process, process parameter, & preparation of AMC material by using aluminium as matrix form and SiC, Al2O3 as reinforcement by varying proportion.