Hybrid Aluminium Matrix Composites Research Articles

Mechanical, tribological, and electrochemical behavior of hybrid aluminum matrix composite containing boron carbide (B4C) and graphene nanoplatelets

Abstract

Elucidation on the Microstructural and Mechanical Properties of Tailored VAL12 Hybrid Composites with ZrO<sub>2</sub> Dispersoids Fabricated by Squeeze Casting Technique

The effect of ZrO2 (2, 4, 6 and 8 wt%) dispersoids with 1 wt% graphite on the microstructural, mechanical properties on squeeze cast VAL12 matrix hybrid composite is investigated in the present study. The hybrid composites were characterized using advanced characterization techniques to reveal its microstructural and physical properties. The microscopic examinations using optical and SEM technique reveal that the addition of dispersoids accelerates the nucleation kinetics, thus attaining fine, equiaxial grains in hybrid composites. The squeeze cast composites show almost nil porosity, defects and owing to it, the actual density of the composites are found to be more than 95% as that of the theoretical density values. The hardness values and tensile values increase with respect to the increase in percentage addition of ZrO2. The tensile results show that there is an appreciable increase in the UTS values of composites without much loss in its ductility as the addition of graphite improves the self-lubricating property and provides wettability during the casting. Fractographic studies on tensile tested specimen reveal that the crack occurs in both matrix and particles showing the good interface between matrix and dispersoids. Machinability studies reveal the formation of continuous chips in hybrid composites with a lower percentage of reinforcement (up to 4% ZrO2 + 1%Gr) and segmented chips in case of the composite with 8% ZrO2 + 1%Gr, as the increase in the percentage of dispersoids improve the chip breakability of the composites. On an overall, the hybrid aluminium matrix composites with 1%Gr and 6 % ZrO2 unveiled better optimal results.

Morphological and Mechanical Characteristics of Hybrid Aluminium Matrix Composites

In emerging trend day by day the world facing lot of new invention in automobiles and aerospace industries. They need new smart materials lighter in weight, tensile strength and hardness with good thermal shock resistance compared to available conventional metals. Especially the aluminium based Metal Matrix Composite (MMC) materials can provide these properties. In this research article an attempt is made to find the mechanical properties and morphological of the aluminium alloys of Al 356 mixed with silicon carbide particles (SiCp) and Mica. All these three different MMCs were fabricated in stir casting method. Their tensile strengths are studied and compared with the help of Vickers micro hardness tester and tensile testing machine. The morphological characteristics are tested and compared with the Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDAX) optical microscopy. The tensile strength and hardness of MMCs were comparatively increased than the aluminium alloys.

Fabrication and property evaluation of Al 6061 + x% (RHA + TiC) hybrid metal matrix composite

The present work aims in understanding the mechanical properties and strengthening behavior of Al 6061 based particulate hybrid aluminium matrix composites (PHAMCs) reinforced with rice husk ash (RHA) and TiC particles (sizes; 10 µm) fabricated by liquid metallurgical route. RHA + TiC particles (3 wt%, 5 wt%, 7 wt%, and 9 wt%) are added in equal proposition in the hybrid composite which is fabricated through stir-casting technique. Samples are named as S1, S2, S3, S4 based on the proposition of RHA and TiC, whereas Al 6061 alloy is casted and named as S0. Fabricated composites were homogenized at 400 °C for 1 h and then aged to 115 °C for 24 h. X-ray diffraction result confirms the presence of principle elements like Al, TiC, Si and oxygen without the formation of any intermetallic elements. Property of PHAMCs such as ultimate tensile strength, yield strength, and micro Vickers hardness had improved by 31%, 17.1%, and 18%, respectively with increase in the percentage of reinforcement. Addition of reinforcement slightly lowers the mechanical properties of PHAMCs which is due to agglomerations and porosity. Reinforcement with more than 7% of RHA and TiC in matrix significantly effect the density, impact energy and percentage of elongation to a maximum of 3.88%, 28.52%, and 29.91%, respectively. Microstructure of the fractured surfaces are analysed through SEM and it is reported.

Investigation of rare earth particulate on tribological and mechanical properties of Al-6061 alloy composites for aerospace application

Current research work emphasis on the development of rare earth particulate (REP) reinforced hybrid aluminium matrix composites processed by stir casting route. The weight percentage of CeO2 as rare-earth particulate varied from 0.5 wt% to 2.5 wt% and SiC /Al2O3 varied from 2.5 wt% to 7.5 wt%. The presence of rare earth particulate helps in grain refinement of the matrix with well defined grain boundaries is seen via Electron Backscatter Diffraction (EBSD) analysis. The Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) examination were used to characterize the prepared samples of Al-6061 hybrid composites. Porosity analysis, Vickers microhardness, tensile behavior, flexural strength and impact strength of the hybrid composites improved significantly with the addition of rare earth particulate. The flexural strength of the Al-6061 hybrid composites is found to be increased upto 44.76% by increased weight percentage of rare earth oxide phase. The optimum quantity of CeO2 as RE that favours the better tribological and mechanical characteristics of aluminium hybrid composites was found to be 2.5 wt%. The results of wear tests showed an improvement of wear rate around 87.28% when compared to Al-6061 alloy with the addition of 2.5 wt% of CeO2. Finally, the worn out surface of the hybrid composites is examined with the help of scanning electron microscope to understand the wear mechanism of the composites for aerospace application.

Effects of nano-sized ceramic particles on the coefficients of thermal expansion of short SiC fiber-aluminum hybrid composites

Coefficients of thermal expansion (CTE) for short SiC fiber-reinforced aluminum matrix hybrid composites (AMHCs) containing nano-sized SiC particles are predicted through a novel multi-step micromechanics approach. The thermo-mechanical properties of aluminum matrix filled with SiC nanoparticles are extracted utilizing an analytical micromechanics model as a first step. These effective properties are then used in the Mori-Tanaka method to obtain the effective CTEs of AMHCs. The modeling of nanoparticle agglomeration often formed in real engineering situations, is accomplished using a nested method. The predictions of the developed micromechanical model are compared to experimental measurements available in the literature, and an acceptable agreement is observed between them. The effects of the volume fraction, diameter and agglomerated degree of SiC nanoparticles, and also the volume fraction and aspect ratio of SiC short fibers on the AMHC CTEs are investigated. In addition to randomly oriented fiber-reinforced AMHCs, modeling of the effective CTEs of aligned short fiber-reinforced AMHCs is performed. The results reveal that addition of nano-sized SiC particles reduces the CTE of short SiC-fiber-reinforced AMHCs. The decrease of particle size and increase of fiber aspect ratio also assist in improving the overall thermo-elastic properties of AMHCs. However, the presence of the ceramic nanoparticle agglomeration leads to increase the AMHC CTEs. According to the micromechanical analysis, it is found that the alignment of short fibers is an efficient method to reduce the AMHC CTEs.

Effect of fly ash and ball milling time on CNT-FA reinforced aluminium matrix hybrid composites

In this paper, Aluminium metal matrix hybrid composite was fabricated using powder metallurgy, where MWCNT and burnt coal waste (pollutant) used as reinforcing materials. The density and hardness of specimen was calculated and influence of fly ash on them was discussed. It was observed that hardness had increasing effect for certain weight percentage of fly ash( up to 8 wt%) and above that level showed the negative effect on them. An increase of 63.6% in hardness and 107% in compressive strength was observed for the composite compared to pure aluminum. The increased ball milling time resulted in damage of CNT. Compressive strength test revealed that MWCNT along with fly ash addition resulted in the improvement of compressive strength compared to pure Al.

Effects of garnet particles and chill casting conditions on properties of aluminum matrix hybrid composites

In recent years, the demand of high-performance and light-weight materials was increasing for industrial applications. The present research aims to study microstructural and mechanical properties of aluminum matrix hybrid reinforced 6-12 wt.% of garnet under the effects of materials chill casting during the manufacturing aluminum matrix composite. In this research work, metallic mold and no chills were used. In order to evaluate the quality of the chill end casting microstructure, hardness, and tensile tests were conducted on the prepared composite specimens. Aluminum matrix composites underwent the chill casting process have been examined using the optical microscope, scanning electron microscopy and X-ray diffraction. Microstructure outcomes of the casted Al-composites alloy indicated that having precipitations (Al2Si, AlCuMg2Si) and Garnet particulates hard within the Al-matrix. The results showed that the copper chill casting is the better one in terms of improving the mechanical properties because of its high volumetric heat capacity. Aluminum composite with addition of 9% Garnet composite produced via copper chill casting exhibits better mechanical properties.

In Situ Hybrid Aluminum Matrix Composites: A Review of Phase Transformations and Mechanical Aspects

The growing industrial needs for the development of strong load‐bearing materials by powder metallurgy and casting technologies has led to recent progress in the synthesis of in situ hybrid aluminium matrix composites (AMCs). Unlike their conventional counterparts, this class of engineering materials and their physicomechanical properties are sparsely investigated with no satisfactorily systematic approach and are not reviewed up to now. This is why providing an overview summarizing the formation mechanisms of in situ phases and mechanical properties of hybrid AMCs can systematically guide the research path in this field. The present review strives to categorize hybrid AMCs based on their dominant in situ formed reinforcements and draw a comparison between different fabrication methods and used starting materials. Finally, the present challenges and potential solutions are addressed both from scientific and technological aspects.

Development of rare-earth oxides based hybrid AMCs reinforced with SiC/Al2O3: mechanical & metallurgical characterization

The paper presents the study on the mechanical and microstructural behaviour of aluminium matrix hybrid composites of Al-6061 alloy with Al2O3, SiC and CeO2 as reinforcement particles processed through stir casting route. For the experimental investigations, hybrid composites were fabricated by varying weight percentages of 5,10 and 15wt.-% of (SiC+Al2O3) mixture and weight percentage of 0.5, 1.5 and 2.5wt.-% of CeO2 keeping total wt.-% of reinforcement less than 30wt.-%. Mechanical properties like ultimate tensile strength, micro and macro hardness and percentage elongation were examined on the aluminium matrix hybrid composites at room temperature. The microstructure analysis was done using SEM, XRD and EDS techniques. Micro hardness value of the base alloy was increased by 17.02% on addition of 2.5wt.-% of CeO2 as rare earth element along with (Al2O3+SiC) mixture. In comparison to non-rare earth element (Alloy+15wt.-% (Al2O3+SiC) mixture), the hardness increased by only 13.70%. Rockwell hardness of the base alloy increased by 33.80% on successful incorporation of rare earth element. The SEM microstructure analysis shows a very significant refinement of the composites after addition of rare earth particles. XRD and EDS analysis shows very good results in terms of fabrication of hybrid composite particles.

Microstructure and Properties of AA6082/(SiC + Graphite) Hybrid Composites

Hybrid aluminum matrix composites (HAMCs) reinforced with different amounts of ceramic particulates consisting of silicon carbide (SiC) and graphite (Gr) were developed. The amount of ceramic powder was 5 – 15 mass%. Parameters of the hybrid composites such as microstructure, density, and porosity and mechanical properties such as hardness and tensile strength were analyzed. Scanning-electron-microscope photomicrographs showed a uniform distribution of (SiC + Gr) particles in the Al matrix. The density and porosity of the hybrid composite increased from 2.69 to 2.72 g/cm3 and from 0.37 to 1.20%, respectively; Vickers hardness and tensile strength, from 49.5 to 85 VHN and from 161.5 to 187 MPa, respectively. The relative elongation decreased from 8.6 for 5.3 as the content of ceramic particulates (SiC + Gr) increased from 0 to 15 mass%.

A review of microstructure, mechanical properties and wear behavior of hybrid aluminium matrix composites fabricated via stir casting route

This article focuses on the mechanical and wear properties of the Al-based hybrid composites fabricated by stir casting route. A wide range of literature has been consulted in this regard and it has been revealed that processing conditions can be tailored to obtain homogeneous structure of the Al-composites. The addition of ceramic particles has been found to be essential to provide requisite strength and hardness to these composites. Also, use of agro/industrial waste materials such as fly ash, red mud and rice husk ash as a complementary reinforcement reduces the density of the hybrid composites without compromising the mechanical properties. The literature review also indicates that addition of soft reinforcements along with hard reinforcements reduces the brittleness of the hybrid composites. Moreover, the presence of solid lubricants like graphite significantly improves the wear resistance of these materials. It has been noticed that incorporation of solid lubricants also helps in the formation of a protective tribolayer at the interface thereby reducing the wear rate and plastic deformation of these composites. In overall, study concludes that Al-based hybrid composites have great promise to serve as a substitute to the ceramic reinforced composites and the unreinforced Al-alloys in various automotive applications requiring low cost, high strength-to-weight ratio and superior wear resistance.

Investigation on microstructural, physical and mechanical properties of AA6082/(SiC + + Graphite) hybrid composites

The current research work prominences on the development of hybrid aluminium (AA6082) matrix composites (HAMC) reinforced with different weight percentages of (silicon carbide (SiC) + graphite (Gr)) ceramic particulates by conventional stir casting process. The weight percentage of combined ceramic powder is varied from 5 to 15 wt. % in a stage of 5 wt. %. The microstructures, physical properties such as density and porosity as well as mechanical properties like hardness and tensile strength of the fabricated hybrid composites are analyzed. The scanning electron micrographs reveal the uniform distribution of (SiC + Gr) ceramic particulates in the aluminium matrix. The uniform distribution of reinforcement particles has also been verifed with the help of elemental maps of different element present in the hybrid composites. Density and porosity of hybrid composite increases from 2,69 to 2,72 g/cm3and from 0,37 to 1,20 %, both the hardness as well as ultimate tensile strength have enhanced from 49,5 to 85 VHN and from 161,5 to 187 MPa respectively with a reduction in percentage elongationfrom 8,6 to 5,3 with rise in weight percentage of (SiC + Gr) ceramic particulates in the aluminium matrix from 0 to 15 wt. % respectively.Ill. 8. Ref. 49. Tab. 1.

Investigations of the Tribological Performance of A390 Alloy Hybrid Aluminum Matrix Composite.

Several challenges stand in the way of the production of metal matrix composites (MMCs) such as higher processing temperatures, particulate mixing, particulate–matrix interface bonding issues, and the ability to process into desired geometrical shapes. Although there are many studies showing composites with single particulate reinforcements, studies on composites with multiple reinforcing agents (hybrid composites) are found to be limited. Development of a hybrid particulate composite with optimized mechanical and tribological properties is very significant to suit modern engineering applications. In this study, Al–Si hypereutectic alloy (A390) was used as the matrix and silicon carbide (SiC), graphite (Gr), and molybdenum di-sulphide (MoS2) were used as particulates. Particulate volume (wt %) was varied and sample test castings were made using a squeeze casting process through a stir casting processing route. The evaluation of the mechanical testing indicates that the presence of both the hard phase (SiC) and the soft phase had distinct effect on the properties of the hybrid aluminum matrix composites (HAMCs). Composite samples were characterized to understand the performance and to meet the tribological applications. The 3D profilometry of the fractured surfaces revealed poor ductility and scanning electron microscopy fractography study indicated an intra-granular brittle fracture for HAMCs. Also, the dry sliding wear tests indicated that the newly developed HAMCs had better tribological performance compared to that of A390 alloy.

Investigation on mechanical properties of aluminium 7075 - boron carbide - coconut shell fly ash reinforced hybrid metal matrix composites

The present research work reports the fabrication and evaluation of the mechanical properties of hybrid aluminium matrix composites (HAMC). Aluminium 7075 (Al7075) alloy was reinforced with particles of boron carbide (B4C) and coconut shell fly ash (CSFA). Al7075 matrix composites were fabricated by stir casting method. The samples of Al7075 HAMC were fabricated with different weight percentages of (0, 3, 6, 9 and 12wt.%) B4C and 3wt.% of CSFA. The mechanical properties discussed in this work are hardness, tensile strength, and impact strength. Hardness of the composites increased 33% by reinforcements of 12wt.% B4C and 3wt.% CSFA in aluminium 7075 alloy. The tensile strength of the composites increased 66% by the addition of 9wt.% B4C and 3wt.% CSFA in aluminium 7075 alloy. Further addition of reinforcements decreased the tensile strength of the composites. Elongation of the composites decreased while increasing B4C and CSFA reinforcements in the matrix. The impact energy of the composites increased up to 2.3 J with 9wt.% B4C and 3wt.% CSFA addition in aluminium alloy. Further addition of reinforcement decreased the impact strength of the composites. The optical micrographs disclosed the homogeneous distribution of reinforcement particles (B4C and CSFA) in Al7075 matrix. The homogeneously distributed B4C and CSFA particles added as reinforcement in the Al7075 alloy contributed to the improvement of hardness, tensile strength, and impact strength of the composites.

Study on thermal and mechanical properties of yttrium tungstate-aluminium nitride reinforced aluminium matrix hybrid composites

Aluminium matrix hybrid composites (AMHCs) containing 30 wt % Y2W3O12 - (0, 5, 10, 15 wt %) AlN and 30 wt % AlN - (0, 5, 10, 15 wt %) Y2W3O12, defined as Y2W3O12 and AlN rich composites, respectively, were prepared by high energy ball milling followed by compaction, sintering and forging. The hardness, compressive strength, coefficient of thermal expansion (CTE), thermal conductivity and thermal stability of all the composites were evaluated. A high compressive strength (500–520 MPa) along with a low CTE (12–14 × 10−6 K−1) is achievable in such hybrid composites by adjusting the amount of individual reinforcement. The thermal cycling experiments suggest that the composites are thermally stable. The thermal conductivity of the Y2W3O12 rich composites increases with an addition of AlN, whereas it decreases in the AlN rich composites with an addition of Y2W3O12.

Wear characteristics of hybrid aluminum-matrix composites reinforced with well-dispersed reduced graphene oxide nanosheets and silicon carbide particulates

In the present study, hybrid composites consisting of a hypoeutectic aluminum-silicon (Al-Si) matrix with silicon carbide (SiCp) (10 wt%) and various reduced graphene oxide (RGO) (0.3–0.7 wt%) contents were fabricated using a combined solution-mixing and powder metallurgy (PM) route. The tribological behaviors of these composites against a GCr15 steel ball were studied under dry sliding-wear conditions using a ball-on-disc configuration. The effects of the RGO content and applied loads on the coefficient of friction (COF) and wear rates were evaluated. To study the wear mechanism, comprehensive characterization of the worn surfaces and debris was performed using scanning electron microscopy (SEM). In contrast with the Al-Si/SiCp composite, the hybrid Al-Si/SiCp/RGO composites showed reduced wear rates because of the stabilized COF, and the self-lubricating effects of the incorporated RGO. In the case of all the composites, the wear rate increased as the load increased. Delamination wear is the dominant wear mechanism of the Al-Si/SiCp composite, at both low and high loads. At low loads, the dominant wear mechanism of the Al-Si/SiCp/RGO hybrid composites is abrasive wear accompanied by adhesion wear; this transitions to delamination wear at high loads.

Hot deformation behavior and mechanism of hybrid aluminum-matrix composites reinforced with micro-SiC and nano-TiB2

The hot compression tests of hybrid aluminum-matrix composites reinforced with micro-SiC and nano-TiB2 were performed at deformation temperature of 350–500 °C and strain rates of 0.001-1s−1 on Gleeble-3500 system. The corresponding deformed microstructures were characterized by electron back scattered diffraction (EBSD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the true stress increased rapidly with the increase of the true strain and then stabilized or decreased slightly after the true stress reaches the peak value. The peak stress levels increased with the decrease of deformation temperature and the increase of strain rates. The flow stress behaviors of the hybrid composites can be described by the sine-hyperbolic Arrhenius equation with the deformation activation energy of 269.7 kJ/mol. The main flow softening mechanism of the hybrid composites is dynamic recovery (DRV), accompanied by partial dynamic recrystallization (DRX). In particular, the addition of TiB2 nanoparticles promotes dislocation pile-up and simulates DRX nucleation.

An Investigation on the Mechanical Properties of Nano-Al2O3 and TiC Reinforced Aluminum Matrix Hybrid Composites

An Investigation on the Mechanical Properties of Nano-Al₂O₃ and TiC Reinforced Aluminum Matrix Hybrid Composites

Microstructure and mechanical characterization of in situ synthesized AA6061/(TiB2+Al2O3) hybrid aluminum matrix composites

TiB2 and Al2O3 particulates reinforced AA6061 aluminum matrix composites (AMCs) were synthesized by in-situ reaction of titanium (Ti) and boric acid (H3BO3) powders with molten aluminum. AMCs were fabricated using an electric stir casting furnace under a controlled environment. Heat flow curves of differential thermal analysis (DTA) showed that the synthesis temperature for the formation of TiB2 and Al2O3 using Al-Ti-H3BO3 reaction system was 950 °C. The in-situ synthesized composites were characterized using XRD, FESEM, TEM and EBSD. XRD results revealed the formation of TiB2 and Al2O3 particulates in the composite. FESEM micrographs revealed a homogenous distribution of both the particulates with good interfacial bonding. EBSD maps showed that the in-situ formed TiB2 and Al2O3 particulates refined the grains of the aluminum matrix from 103 μm at 0 wt% to 14 μm at 15 wt%. Al2O3 particles exhibited spherical shape while TiB2 particles displayed hexagonal and cubic shapes. The formation of ultrafine and nano scale thermodynamically stable TiB2 and Al2O3 particles enhanced the microhardness and the tensile strength of the AMCs. The microhardness and the tensile strength were respectively 122 HV and 287 MPa at 15 wt%.