AA6061 Matrix Research Articles

The effect of plastic deformation on mechanical properties of aluminium matrix composites reinforced with 2D crystals

Abstract In this study, AA6061 matrix composites reinforced with multilayer graphene and MoS2 were analyzed. The composites were prepared by powder metallurgy using the spark plasma sintering and spark plasma texturing methods. Microstructure, physical and mechanical properties were investigated and compared with unreinforced AA6061 sinter and AA6061 sheet plate. The results showed that the application of spark plasma texturing positively influences the relative density and compressive yield strength of AA6061 matrix composites. Moreover, in composites with MoS2, significant differences in compressive yield strength between the centre and the edge of the sintered compacts were noticed. These differences are related to the formation of the MoAl12 phase as a result of the temperature gradient generated in the graphite die during sintering by the spark plasma texturing.

Analysis of wear parameters for AA6063–TiC composites using Taguchi technique

The wear behaviour of the AA6063 matrix composite reinforced with different weight percentages of titanium carbide (TiC) particles by the in situ reaction route was studied. The hardness and wear rate of the composite samples were analysed using a hardness tester and a pin-on-disc wear tester. The dry sliding wear behaviour of the composites was investigated based on the Taguchi L16 orthogonal array experimental design. The significance of reinforcement, load and sliding distance on wear rate was explored. Load and sliding velocity were identified as the highly significant parameters on the wear rate using the analysis of variance. Worn surfaces of the composites were analysed using scanning electron microscopy, and all the surface morphology images were reported.

Investigation on mechanical properties of ZrO2, C and AA6061 metal matrix composites

ABSTRACT Zirconium Di Oxide (ZrO2) reinforcement particulates are having superior mechanical properties and graphite (C) reinforcement particulates are having good wear properties. These behaviours offer an increased property for their study in the fabrication of metal matrix composite (MMC) and hybrid metal matrix composite. In maximum adding of reinforcement particulates, the composite material’s properties are reduced. The aim of this study is to investigate the preparation of two types of MMCs suited for equally different compositions. Under the first method, various weight percentages (wt%) of the primary reinforcement (ZrO2) are included from 2 to 10 in aluminium-based metal matrix composites (AMMCs). In the next method, both the primary reinforcement (ZrO2) and the secondary reinforcement (C) are included in the same amount of wt% from 2 to 6 in AMMCs. The maximum strengths obtained as 175 MPa in tensile strength, 45HRB hardness and 4.56E-9 g/mm in 6 wt% of ZrO2 and 2 wt% of C inclusion of 92 wt% of AA6061 matrix material.

The effect of plastic deformation on mechanical properties of aluminium matrix composites reinforced with 2D crystals

Abstract In this study, AA6061 matrix composites reinforced with multilayer graphene and MoS2 were analyzed. The composites were prepared by powder metallurgy using the spark plasma sintering and spark plasma texturing methods. Microstructure, physical and mechanical properties were investigated and compared with unreinforced AA6061 sinter and AA6061 sheet plate. The results showed that the application of spark plasma texturing positively influences the relative density and compressive yield strength of AA6061 matrix composites. Moreover, in composites with MoS2, significant differences in compressive yield strength between the centre and the edge of the sintered compacts were noticed. These differences are related to the formation of the MoAl12 phase as a result of the temperature gradient generated in the graphite die during sintering by the spark plasma texturing.

Experimental assessment of self-healing nature in aluminum-based smart composites with NiTi wires and solder alloy as healing agents through Taguchi approach

In this article, the healing assessment of the AA2014 matrix reinforced with NiTi wires and solder alloy as healing agents is investigated through flexural testing. The idea of a smart composite was such that it could retain its structural stability through NiTi wires reinforced, which ultimately heals the macro cracks, whereas the solder alloy binds the micro-cracks by filling through the gap after heat treatment. The objective of this work is to determine the parameters influencing self-healing assessments. Specimens with different shape memory alloy vol% (0.5%, 1.3%), specimen size (1, 2) and shape memory alloy wires diameter (0.47 mm, 0.96 mm) were fabricated for analysis. Furthermore, Taguchi orthogonal columns of L8 (4^1 2^3) array technique was implemented to study the observations from different experimental runs. Healing temperature (i.e. 600°C) was selected such that it could take advantage of the compositional healing of the matrix. The completely damaged specimens through the bend test were thermally treated at different healing durations (30, 60, 90, 120 min) in a furnace to activate healing. The results show that a maximum of 96.95% of crack depth, 100% of crack width, and 73.76% of the recovery in flexural strength was recovered after heat treatment.

Reusing exhausted alkaline battery powder as reinforcement in AA6061 composites and mechanical characterization

ABSTRACT One of the practical difficulties in replacing the conventional alloys with composite material is the cost of the synthetic reinforcement used in all types of composite materials. In the last two decades, several agricultural and industrial wastes were tried as reinforcement in polymer and metal matrix to enhance the mechanical and tribological properties of the composites. It is the need of the hour to develop the low-cost composites which can be achieved by reusing the commercial wastes as reinforcement in metal matrix materials. In this study, Aluminum alloy (AA6061) was used as matrix material. Alkaline battery powder after usage was reinforced in AA6061 matrix in different volume percentages (2, 4, 6, 8, and 12 vol %). The tensile properties of composite materials were evaluated using ASTM standards. The 6 vol % of used up alkaline battery powder in AA6061 improved the tensile properties after which a decrement in properties was observed. The porosity and agglomeration of reinforcement were noted as the prime reason for the decrement in properties. The ductile fracture was noticed in composites that possessed reinforcement volume of up to 6%. The combination of ductile and brittle was found in the composites with 8 and 12 vol % of reinforcement.

Modeling of cylindrical upsetting process for enhanced ductile fracture

The demand of the automobile and aerospace industries to produce light weight parts provides scope for analyzing the formability of AA2014 cast alloys. The addition of industrial waste like fly ash lowers the ductility and the formability characteristics needs to be investigated. Upsetting being a primary metal forming operation and the fracture initiation depends upon the amount of fly ash added to the AA2014 matrix, height to the diameter (h/d) ratio and friction at the die/billet interface. To predict the effect of these process parameters on the fracture initiation behavior Taguchi’s optimization technique was applied for cylindrical upsetting. The experimental results proved that the formability of the material depends on the lubricant employed at the die/billet interface, height to the diameter ratios and the strength parameter. The formability was measured in terms of effective strain to improve the incipient fracture. Using ANNOVA analysis, the percentage contribution of each factor was determined. Ductile fracture criterion was modified using Hills equation to determine the critical damage for any friction condition. The results obtained from the finite element simulations are in good agreement with the results obtained from the modeled empirical equation.

Instrumentation Based Microstructural Characterization of the Friction Stir Welded SiC/B4C Aluminium Metal Matrix Composites and Optimization of Governing Process Parameters

Aluminium Metal Matrix Composites reinforced with particulate silicon carbide and Boron Carbide reinforcements have demanding applications in aerospace and automotive domains. With a lack of sufficient literature on this composite combination and emerging demands, it is highly essential to understand their weldability and material characteristics. Friction Stir Welding is a feasible choice for joining of Aluminium Metal Matrix Composites over the conventional fusion welding owing to narrow Heat Affected Zone and minimized Intermetallic Compound formation at the weld interface. In this work, AA6061 matrix composite plates are fabricated with a varying weight percentage of particulate SiC and B4C reinforcements using powder metallurgy process. The study mainly focusses on the tensile strength, hardness and microstructural properties of composite plates joined using Friction Stir welding subjected to a constant load of 8KN at three-level process parameters experimental design of varying spindle speed, weld speed and plunge depth. The outcomes reveal sufficient information on the microstructural analysis of the weldments and the subsequent effects on the material strength. Followed by, statistical process parameter optimization is performed to improve the tensile properties of the weldments and the results are experimentally validated. The study confirms the feasibility and applicability of FSW in joining Al-MMCs.

DRY SLIDING WEAR AND SURFACE MORPHOLOGICAL EXAMINATION OF AN ALUMINIUM MATRIX COMPOSITE REINFORCED WITH PALM KERNEL SHELL

The wear resistance and microstructural features of aluminum AA6063 based composites reinforced with seven different mass fractions of palm kernel shell particles (0, 2.5, 5, 7.5, 10, 12.5 & 15wt%) fabricated by stir-casting, were characterized using pin-on-disk tribometer, optical microscope, and ImageJ package. ImageJ particle analysis revealed both the particle size and shape descriptors for the composites' microstructural features. The average grain sizes of all the composites were higher than that of the unreinforced AA6063 matrix. Wear tests conducted under dry sliding condition show that the volume reduction and specific wear rate increased to a maximum at 5wt% PKS addition and then decreased to the lowest level at 10wt% PKS. Subsequent addition of PKS above 10wt% yielded a further increase in the composites volume loss and specific wear rate. Composite sample reinforced with 10wt% PKS exhibited wear resistance response better than that of the unreinforced alloy. Image analysis afforded a comprehensive understanding of the microstructural features of the composites which influenced their behaviors.

Effect of compaction pressure on mechanical properties of AA7075/B4C/graphite hybrid composite fabricated by powder metallurgy techniques

Composite materials are at top in material selection process due to its superior mechanical and tribological properties, properties of a composite can be modified by reinforcing different hard ceramic particles in a matrix material depend upon the requirement needed. Strength of the composite can be improved by creating good interface bond between matrix and reinforcements which can be achieved by selecting proper processing parameters i.e., compaction pressure, sintering temperature, sintering time. Present work focuses on fabrication of AA7075/B4C/Graphite hybrid composite by varying the compaction pressures while cold compaction process. In AA7075 matrix material 6 wt% Boron carbide (B4C) and 2 wt% graphite was added to optimize the ductility and brittleness of the composite material. Mechanical response of the hybrid composite was noted in compression and hardness tests, results reveal that increased compaction pressure has very positive impact on mechanical properties of the composite material, micro structural analysis reveals effect of increased compaction pressure clearly.

Effect of graphene addition on the mechanical characteristics of AA7075 aluminium nanocomposites

Processing and characterization of graphene (Gr)-reinforced aluminium alloy 7075 (AA7075) microcomposites and nanocomposites are reported in this work. Composites are fabricated by mechanical alloying process at wet conditions. The bulk composites are prepared by uniaxial die pressing to get higher densification and sintered in an inert atmosphere. Density of the nanocomposites is higher than the microcomposites due to the reduction of grain size by increased milling time. X-ray diffraction (XRD) analysis confirms graphene interaction with the AA7075 matrix lattice spaces. The effective distribution of graphene with aluminium alloy is further confirmed by the Transmission Electron Microscopy (TEM) analysis. The hardness of the composites proportionally increases with the graphene addition owing to grain refinement. Wear morphology is characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Microcomposites reveal abrasive and ploughing wear mechanism of material removal from the surface. Nanocomposites show adhesive wear with delamination and particle pull-out from the material surface.

Corrosion behavioral studies on AA7075 surface hybrid composites tailored through friction stir processing

PurposeThis paper aims to overcome the corrosion in AA7075 by incorporating the dual-reinforcements like Al2O3 and SiC through friction stir processing (FSP). In recent days, an automotive monocoque structure undergoes corrosion because of changes in environmental conditions.Design/methodology/approachSurface hybrid composites (SHCs) of AA7075 with different weight ratios of Al2O3 and SiC were fabricated at a rotating speed of 1000 rpm, traveling speed of 56 mm/min and tool tilt angle of 2º with two passes. Surface regions were observed using optical microscopy, and the potentiodynamic corrosion test was performed under a 3.5 per cent NaCl environment at room temperature. Then, the surface morphology analysis of corroded samples and their structural properties were also investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron dispersive spectroscopy (EDS).FindingsThrough FSP, an improved interface between the reinforced particles and the AA7075 base matrix was observed because of the severe plastic deformation. Potentiodynamic polarization tests confirmed that the AA7075 matrix with a higher concentration of Al2O3 and a lower concentration of SiC (Al2O3 – 75 per cent and SiC – 25 per cent) possesses a lower corrosion rate than other specimens. This result is because of the combined effect of stable passive film formation and the resistance produced by hard SiC particles. In addition, the formation of a stronger interface between the reinforcements and the base matrix impedes the NaCl solution attack. The SEM micrograph depicts the film crystallinity variations with an increase in Al2O3 content. Debonding between the layers was observed on increasing the SiC content in the base matrix. XRD shows the peaks of reinforcing elements that influence the corrosion behavior. These observations suggest that the AA7075 reinforced with a higher concentration of Al2O3 and a lower concentration of SiC through FSP affords a suitable solution for automotive monocoque applications.Originality/valueThe corrosion rate has been identified for AA7075 SHCs with various concentrations of Al2O3 and SiC and has been compared with that of the base metal and the friction stir processed specimen without reinforcement.

Synthesis and characterization of 7075 Al alloy–SiC composites

PurposeMechanical properties are highly sensitive to the microstructure, and these are indirectly related to solidification parameters and processing conditions. AA7075 possesses lightweight and excellent properties as structural material which can be optimized with SiCp addition and a good fabrication technique.Design/methodology/approach7000 series aluminium alloys exhibit the highest mechanical properties. They are used for high-strength structural applications such as aircraft parts and sporting goods. The desirable properties of these alloys are: low density, high stiffness, specific strength, good wear resistance and creep resistance. The focus of this work is to investigate the microstructure of composites formed by the dispersion of silicon carbide particles (SiC) into AA7075 by stir casting processes. 7075 Al alloy is reinforced with 10 and 15 wt.% SiCp of size 10–20 µm by stir casting process. The composites have been characterized by X-ray diffraction and scanning electron microscopy, differential thermal analysis and electron probe microscopic analysis.FindingsSiCp distribution and interaction with AA7075 matrix have been studied. AA7075/10 wt.%/SiCp (10–20 µm) and AA7075/15 wt.%/SiCp (10–20 µm) composites microstructure showed excellent SiCp distribution into AA7075 matrix. In addition, no evidence of secondary chemical reactions has been observed in X-ray diffraction and electron probe microscopic analysis.Originality/valueLittle experimental work has been reported so far about effect of addition of 10 and 15 wt.% SiCp of size (10–20 µm) on the microstructure of 7075 Al alloy fabricated by stir casting process. The present investigation has been carried out to study the microstructure and carry out XRD, DTA and EPMA analysis of 7075 Al alloy, 10 and 15 wt.% SiCp of size (10–20 µm) composite and detect the interfacial reactions with the objective to minimize the formation of Al4C3.

Studies on High Temperature Wear and Friction Behaviour of AA6061/B4C/hBN Hybrid Composites

This present work deals with the use of hexagonal boron nitride (h-BN) as a solid lubricant for AA6061/B4C composite due to its special features of self-lubricating property, thermal and chemical stability. The wear behaviour of composites at elevated temperature test, varied from 27 to 300 °C, was performed for AA6061 alloy with boron carbide (B4C) 5–15 wt% and h-BN 5–15 wt% reinforced hybrid composites under a load of 10 and 45 N at constant sliding velocity and sliding distance of 2.2 m/s and 2500 m. The prepared composites were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis. The mechanical properties of hybrid composites were evaluated using tensile testing and hardness. The microstructural results revealed a homogenous distribution of reinforcement particles and grain refinement in the composites up to 10 wt% of h-BN. The tensile test results showed a significant improvement in the tensile strength up to 82% attained for the 15% B4C and 5% h-BN hybrid composite compared to AA6061 matrix alloy. The wear behaviour and different wear mechanisms under various testing conditions were explored. The mild-severe wear transition is noticed with increasing load and temperature for AA6061. The wear properties of a hybrid composite of C10N10 exhibited superior wear resistance due to the complete lubrication effect on the entire worn surface. The predominant wear of abrasive and adhesion occurred at room and elevated temperatures and low load conditions. Oxidative wear, plastic deformation, and delamination wear were operating with an increase in load and temperature.

Mechanical and tribological characteristics of boron carbide reinforcement of AA6061 matrix composite

The use of boron carbide-reinforced aluminium matrix composites has grown rapidly in critical applications of aerospace industries, automotive sectors, military, and nuclear engineering. However, boron carbide reinforcement within AA6061 alloy is worthy of investigation in terms of its mechanical and tribological properties. Novel aluminium matrix composites were developed with three different reinforcements (i.e. 5, 10, and 15 wt% of B4C) by using the stir casting process. The developed samples were then tested for performance in terms of mechanical properties (i.e. tensile strength, bending strength, impact strength, shear properties, and micro-hardness). The microstructure of the developed samples was analysed using a scanning electron microscope. By adding 5% B4C reinforcement, the samples display enhanced mechanical properties (high bending, increased resistance to impact test, and shear strength). The micro-hardness tends to increase by increasing the percentage of reinforcement. The novel composites have superior wear resistance due to an increase in the content of B4C particles. The measurements indicate that the wear rate resistance is significantly higher for the composite material with a large amount of B4C particles when was compared with AA6061 alloy. The patterns of surface analysis reveal a homogeneous distribution of ceramic reinforcements in 5 and 15 wt% of B4C samples, as well as a low agglomeration of embedded particles.

Optimization of Abrasive Water Jet Machining Parameters on AA6061/B4C/hBN Hybrid Composites using Grey-RSM

Aluminium Matrix Hybrid Composites (AMHCs) possess an excellent combination of physical and mechanical properties suitable for a variety of applications in automobile and aerospace industries. Addition of solid lubricant hexagonal Boron Nitride (hBN) reduces the complexity in machining of aluminium hybrid composites. Abrasive Water Jet Machining (AWJM) is a non-traditional technique applied for the machining of alloys and composites, due to its better cutting performances. In this work, AA6061 matrix hybrid composites reinforced with B4C (5, 10 and 15vol.%) and hBN (15vol.%) were developed through liquid metallurgy route. The composite were then machined using AWJM. Process parameters considered were abrasive flow rate, water pressure, traverse speed, percentage of reinforcement and mesh size over the responses Kerf Taper Angle (KTA) and Surface roughness (Ra). The experimental design was based on L27 orthogonal array and Grey-RSM analytical tool was applied for optimization. The optimal values of parameter setting for AWJM machining process using Grey RSM methodology were 340 g/min, 200 MPa, 60.06 mm/min, 5.01% and 80 for abrasive flow rate, water pressure, traverse speed, percentage of reinforcement and mesh size were respectively.

Optimization of machining parameters in CNC turning of AA6061-B4C-CNT hybrid composites using Grey-fuzzy method

Aluminium hybrid composites and its machining receives a great attention due to their superior properties like good strength to weight ratio, good castability, machinability, and low cost, suitable for various applications in automotive and aerospace industries. CNC turning is considered as an ideal method for machining of aluminium hybrid composites. Nevertheless, the parameters of turning of aluminium hybrid composites need to be optimized for better and precise machining. Also, the presence of solid lubricants such as Carbon nanotube, Graphite, hexagonal Boron Nitride etc. promotes the machinability of aluminium hybrid composites. In this study, CNC turning on AA6061 matrix based hybrid composites reinforced with Boron carbide (5-15 vol.%) and Carbon nanotube (15 vol.%) was performed. Cutting Speed (rpm):60-180, feed (mm/rev): 0.10-0.20, depth of cut (mm): 0.50-1.00 and percentage of B4C (vol.%) 5-15 were the controlling parameters and responses namely tangential force (N), cutting power (W) and tool wear (mm3/min) were considered for the optimization. Experimental design was made as per Taguchi’s L27 orthogonal array and Grey-fuzzy analytical tool was applied for the optimization. The optimal setting for turning operation on this hybrid composite using Grey-fuzzy analysis were 120 rpm, 0.20 mm/rev, 0.5 mm and 15 vo.% for cutting speed, feed, depth of cut and reinforcement respectively.

Investigation on femtosecond laser ablative processing of SiCp/AA2024 composites

This study presents experimental results of femtosecond laser (λ = 1030 nm, τ = 800 fs) ablation of AA2024, sintered SiC, and SiC-particulate-reinforced aluminum metal matrix (SiCp/AA2024) composites using a scanning method. The aim is to determine the mechanism of femtosecond laser ablation of SiCp/AA2024 composites by a comparative study. Scanning electron microscopy and energy-dispersive spectroscopy reveal the morphological changes in the ablated surface with increasing pulse fluence. The ablation depth and surface roughness measured by a 3D surface profiler indicate interfacial interaction between the AA2024 matrix and SiC particles. Two-temperature modeling (TTM) was applied to analyze the ablation behavior of Al and SiC. The experimental results and TTM analysis indicate that the femtosecond laser ablation of the SiCp/AA2024 composites and the interface interaction in the composites under laser irradiation are due to matrix ablation enhanced by the Fresnel effect and electromagnetic interaction (rather than thermal interaction) at the particle/matrix interface.

Synthesis and abrasive wear performance of stir cast AA6063-TiC composite materials

Typically Aluminum 6063 matrix composites have an extensive wear resistance application due to its high specific strength. Here the stir casting fabricated composites having 0, 3, 6 and 9 wt% of titanium carbide (TiC) are tested using a pin on disc sliding wear test equipment. Loads (P), speed (sliding and rotation) and sliding distance (D) are the input parameters. The improvement in hardness was observed when TiC content increases due to the homogeneous dispersion strengthening mechanism. The incorporation of TiC in the AA6063 matrix reduces the rate of wear (WR) and increases the resistance to wear. The “COF” reduces when the TiC composition increases. The “WR” and COF increase when ‘D’ and ‘P’ increases for all the compositions tested.

Preform-Based Production of Al2O3-Reinforced Aluminium Matrix Composites by Using Various Modification Techniques

Metal matrix composites have a wide range of applications due to their lightweight, high strength and high wear resistance. In this study, Al2O3-reinforced AA7075 matrix composites were produced by using liquid metal infiltration method in two stages. In the first stage of the production, preforms were manufactured by using Al2O3 particles and different binders. Some of the preforms were sintered and some were not sintered. In the second step, liquid metal infiltration was performed on both sintered and not sintered samples. Some preforms were preheated before the infiltration and some were directly subjected to the liquid metal infiltration. The casting process was carried out in two different ways: (1) pouring the molten metal into the fired mould and (2) in situ melting of the metal during the mould firing. Fabricated composites were characterized by XRD, light metal microscopy, SEM, EDS, Brinell hardness and ball-on-disc type wear tests. When the microstructural, mechanical and tribological properties were taken into account, preheating and sintering preforms before casting were determined as performing best with the hardness of ~ 150 HB and the wear rate of 1.1 × 10−4 mm3/(N m), whereas the in situ melting caused decrease in the mechanical strength and wear resistance because of excessive oxidation.