Aluminum Alloy Composites Research Articles

Process Parameters Optimization for Producing AA6061/TiB2 Composites by Friction Stir Processing

Abstract Friction stir processing (FSP) is solid state novel technique developed to refine microstructure and to improve the mechanical properties and be used to fabricate the aluminium alloy matrix composites. An attempt is made to fabricate AA6061/TiB2 aluminium alloy composite (AMCs) and the influence of process parameters like rotational speed, transverse feed, axial load and percentage reinforcement on microstructure and mechanical properties were studied. The microstructural observations are carried out and revealed that the reinforcement particles (TiB2) were uniformly dispersed in the nugget zone. The Tensile strength and Hardness of composites were evaluated. It was observed that tensile strength, and hardness were increased with increased the rotational speed and percentage reinforcement of particles. The process parameters were optimized using Taguchi analysis (Single Variable) and Grey analysis (Multi Variable). The most influential parameter was rotational speed in single variable method and multi variable optimization method. The ANOVA also done to know the percentage contribution of each parameter.

Composites of aluminum alloy and magnesium alloy with graphite showing low thermal expansion and high specific thermal conductivity

High thermal conductivity, low thermal expansion and low density are three important features in novel materials for high performance electronics, mobile applications and aerospace. Spark plasma sintering was used to produce light metal–graphite composites with an excellent combination of these three properties. By adding up to 50 vol.% of macroscopic graphite flakes, the thermal expansion coefficient of magnesium and aluminum alloys was tuned down to zero or negative values, while the specific thermal conductivity was over four times higher than in copper. No degradation of the samples was observed after thermal stress tests and thermal cycling. Tensile strength and hardness measurements proved sufficient mechanical stability for most thermal management applications. For the production of the alloys, both prealloyed powders and elemental mixtures were used; the addition of trace elements to cope with the oxidation of the powders was studied.

Influence of Microalloying (Including Rare-Earth Metals) on the Phase Composition and Properties of Aluminum Alloys

In connection with the search for new materials and the more extensive use of metals and alloys with special physical and chemical properties, rare-earth metals (REMs) are attracting increasing interest not only as alloying additives but also as the main components of structural materials. The Al-Fe alloys are of great practical interest, and the purpose of this work was to study the influence of microalloying by REMs on the mechanical and acoustic damping properties of Al-Fe alloys. REMs were selected as alloying components because of their properties and their widespread use in improving the structure and properties of structural alloys, including mechanical and acoustic damping properties. The results of these investigations are expected to enable the use of secondary Al (i.e., waste Al manufacture with a high Fe impurity concentration) as a base material for the development of structural alloys with improved mechanical properties for use in mechanical and electrical engineering applications. The use of secondary Al will provide economic advantages and will contribute to the conservation of resources.This work is actual because Al alloyed with Fe and REMs can be used as corrosion-resistant materials and conductive materials in electronics and for automotive and aircraft engines, wires, cables, rods, tires and other products of the electrical engineering industry, thus expanding the scope of applications of these alloys [1-4].

Characterization of mechanical properties of aluminium/tungsten carbide composites

Abstract This study deals with the investigation on mechanical properties of aluminium alloy (AA 6082) composites reinforced with tungsten carbide particles. Stir casting process was employed to fabricate the aluminium composite specimen by varying tungsten carbide in 2, 4, 6, 8 and 10% by weight. The composites were exposed to density, hardness, tensile and impact studies. Scanning electron microscope was used to investigate the mechanism of the fractured tensile and impact test specimen. The density, impact strength and elongation of the composites decreased with increase in addition of tungsten carbide, while the hardness of composites increased with increase in tungsten carbide. The tensile strength of the composites increased initially and then tends to decrease. Fracture of the composites is characterized by dimples, voids, cracks, ridges, pits and particle fracture. Brittle fracture of composites in the form of cracks and particle fracture are due to the strong interfacial bonding between the tungsten carbide and aluminium matrix at high strain rate. High impact strength of composites are due to ductile failure in the form of dimples, while low impact strength are due to brittle and plastic deformation characterized by micro and macro cracks, particle fracture.

Increased hot forgeability of 2024Al/Al18B4O33w whisker composites at high strain rates

Whisker reinforced aluminum alloy composites are attractive for structural applications in automotive and aerospace applications. However, their forgeability is limited by their poor ductility at room temperature. The effects of temperatures (350–520°C) and strain rates (0.01–50s−1) on the resistance to microcracking and on the closure of voids are investigated for 2024Al/Al18B4O33w whisker composite as well as unreinforced AA2024 alloy. Under elevated temperature and high strain rate (>450°C, >1.0s−1), there are less cracks and no axial splitting on the surface of 2024Al/Al18B4O33w composite. Test results show lower flow stresses and incipient melting at higher temperatures enable better tolerance of whisker-matrix strain mismatch at the interface during hot compression resulting in increased stabilization of flow stresses. While higher strain rates contribute to increased strain rate hardening, whisker rotation and void closure. It is interesting to note that the unreinforced AA2024 alloy experiences flow localization, surface cracking and plastic instability at temperatures higher than 450°C but the presence of Al18B4O33 in the composite seems to better resist these failure mechanisms resulting in higher forgeability.

Mechanical Characterization of AA7068-ZrO2 reinforced Metal Matrix Composites

Metal Matrix Composites are significantly contributing towards important role in engineering applications and are in the forefront of significant research in present day due to their scientific and technical advantages. Particle or discontinuously reinforced MMCs are relatively inexpensive and are found to possess specific properties compared to fiber reinforced MMCs.Among the various types of particulate reinforcements such as silicon nitride, boron nitride, silicon carbide, titanium carbide, boron carbide and alumina, extensive research has been directed toward the development of zircon particle reinforcement. Zircon reinforced composites are preferred as these composites exhibit relatively high refractoriness, excellent resistance to abrasion, thermal shock and chemical attack compared to composites reinforced with other reinforcements. The present paper aims the investigation on influence of reinforced particles ZrO2 on mechanical properties of aluminum alloy (AA7068) composites which is developed by stir casting technique. The castings produced were machined and samples were fabricated by varying weight percentage of the reinforced particles as 0, 2, 4, 6, and 8 Wt% in volume. SEM and microstructural studies were carried out on all composites and fractured surface of tensile specimens. Microstructural study reveals uniform distribution of reinforcement ZrO2 particles in as cast and AA7068 metal matrix composites. Significant improvement in Hardness and Tensile strength was found with increase in Zirconium di oxide particles in weight percentage of composites. As expected, the percentage elongation diminished with increased weight percentage of reinforcement in the aluminum matrix.

Wear Behavior of PAN- and Pitch-Based Carbon Fiber Reinforced Aluminum Alloy Composites under Dry Sliding Condition

Wear Behavior of PAN- and Pitch-Based Carbon Fiber Reinforced Aluminum Alloy Composites under Dry Sliding Condition

Abnormal Effects of Temperature and Strain Rate on the Ductility of a Carbon Nanotubes Reinforced Al Alloy Composite

Carbon nanotubes reinforced aluminum alloy (CNTs/Al alloy) composite was fabricated by the method of flake powder metallurgy. With Gleeble-3500 system, hot compression tests at different temperatures and strain rates were conducted to investigate the effect of temperature and strain rate on the deformation behaviors of the CNTs/Al alloy composite. Experimental results show that the composite’s ductility is worse at higher deformation temperature within range of 300 oC-450 oC. Additionally, the composite’s ductility is better at higher strain rate, which is against general knowledge. The microstructure before and after deformation were characterized by SEM and TEM. It demonstrates that the grain size of the composite is always in the nanoscale. The abnormal effects of temperature and strain rate on the ductility may be explained by the evolution of work hardening capability at different deformation conditions.

Azide SHS of aluminium nitride nanopowder and its application for obtaining Al-Cu-AlN cast nanocomposite

Method of azide self-propagating high-temperature synthesis (SHS-Az), using sodium azide (NaN3) as a nitriding reagent, was used for obtaining the nanopowder of aluminum nitride (AlN) from precursor that was sodium hexafluoroaluminate (Na3AlF6). The product of burning the mixture of Na3AlF6 + 3NaN3 after water rinsing consisted of micro - and nanoparticles of AlN (65%) and the residue of salt Na3AlF6 (35%). This product of SHS-Az was mixed with copper powder and pressed into a briquette of nanopowdery master alloy Cu- 4%(65%AlN+35%Na3AlF6), which was successfully introduced into aluminium melt at a temperature of 850°C. The salt Na3AlF6 in the product of combustion played a role of flux during introducing into the aluminum melt and was not included in the final composition of the composite alloy. The microstructure of the obtained cast composite aluminum alloy with the calculated composition of Al-1.2%Cu-0.035%AlN showed that the reinforcing particles of AlN of different sizes, including nanoparticles, were distributed mainly along the grain boundaries of the aluminum alloy.

Investigation on Tensile and Impact Behavior of Aluminum Base Silicon Carbide Metal Matrix Composites

Objectives: The scope of this work was to: 1. to fabricate Silicon Carbide (SiC) particle Metal Matrix Composites (MMC) by vortex method; 2. to investigate the effect of SiC particles on the tensile and impact behavior of SiC particle reinforced 6061 aluminum alloy composites. Recently, the material technology has seen many contemporary developments in the field of fabricating new materials which reinstates the current materials for different applications. Amidst these, the composite materials have an important aspect which is a combination of different materials possessing various physical and chemical properties. Methods: This Aluminum base metal Matrix Composite (AMC) has been manufactured by wrought aluminum alloy by varying the weight fractions of silicon carbide to compose five distinct forms of composites. Stir – casting has been chosen as the manufacturing technique, in this study. Findings: The manufactured composites were tested to determine their tensile and impact properties and the result proves that the sample with higher percentage of silicon carbide has better mechanical properties, comparably. Applications: This study essentially focuses on establishing AMC as they find applications on aerospace and automotive industries because of their admirable properties compared with the unreinforced alloysKeywords: Aluminum 6061, Mechanical Properties, Metal Matrix Composite, Silicon Carbide, Stir Casting

Wear Characteristics of Hybrid Al 6063 Matrix Composites Reinforced with Graphite and Fly Ash Particulates

As auto manufacturers strive to meet imposed fuel economy and emissions regulations while producing vehicles with the quality and features that consumer expect, the industry needs to rely on advancements made in the field of metal matrix composites. The efforts of combining or replacing metals with the use of advanced metal matrix composites (MMCs) not only reduce weight, but can also improve safety, reliability and efficiency. A hybrid MMC was developed for the cylinder liner of advanced diesel engines. Composites of Al-6063 aluminium alloy reinforced with, fly ash particulate containing 10% and graphite particulate containing 5, 10 and 15 % were produced by stir casting. The wear and frictional properties of the casted hybrid metal matrix composites were investigated by performing dry sliding wear test using a pin-on-disc wear tester. The investigation was done to find the influence of applied load, sliding speed and sliding distance on wear rate, as well as the coefficient of friction during wearing process. From the investigation, it is evident that wear resistance of Al-6063 is increased while adding the fly ash and graphite reinforcement content. The results were compared with the existing liner material. From this comparative study the Al-6063/fly ash/graphite hybrid metal matrix composite can be the considered as an alternative material for existing cylinder material.

INFLUENCE OF REINFORCEMENT PARAMETERS ON THERMAL CONDUCTIVITY OF LM6 ALLOY/SODA LIME GLASS COMPOSITES THROUGH TAGUCHI’S ORTHOGONAL ARRAY APPROACH

Metal Matrix Composites (MMCs) are an important class of composite materials which provide as alternate substitute for conventional materials, when desired properties are necessary for the applications. Aluminium alloy composites find applications where high strength to weight ratio is mandated. This work aims to characterize the thermal properties like thermal conductivity of LM6 aluminium alloy/glass powder composite developed by stir casting techniques. The effect of glass powder parameters is aimed at characterization on the developed composites. Taguchi’s orthogonal array approach is adopted to reduce the experimentation burden. Parameter levels of glass powder are optimized for the desired thermal conductivity of the composite. KeywordsMMC, LM6 alloy, glass powder, Taguchi’s orthogonal array, thermal conductivity. --------------------------------------------------------------------***------------------------------------------------------------------

Modeling and Analysis on the Influence of Reinforcement Particle Size During EDM of Aluminum (Al/3.25Cu/8.5Si)/Fly Ash Composites

In the present study, aluminum alloy (Al/3.25Cu/8.5Si) composites reinforced with fly ash particles was fabricated using stir casting technique. Fly ash particles of three different size ranges 53–75, 75–103 and 103–125[Formula: see text][Formula: see text]m of 3, 6 and 9 weight percentages was reinforced in aluminum alloy. The effect of peak current, pulse on time, and pulse off time on surface roughness (SR), material removal rate (MRR) and tool wear rate (TWR) of electric discharge machining (EDM) was investigated. A central composite design using response surface methodology (RSM) was selected for conducting experiments, and mathematical models were developed using Design Expert V7.0.0 software. Analysis of variance (ANOVA) technique was used to check the significance of the models developed. Peak current was the major factor influencing the EDM of aluminum fly ash composites. The MRR, TWR, and SR of aluminum fly ash composites were also influenced by the size of the fly ash particles.

Dry Sliding Wear Behavior of Palmyra Shell Ash–Reinforced Aluminum Matrix (AlSi10Mg) Composites

ABSTRACTHigh strength, light weight, ease of fabrication, excellent castability, and good wear resistance make aluminum alloy composites suitable for commercial applications. In this work, a silica-rich ash particle (palmyra shell ash) was reinforced with aluminum alloy (AlSi10Mg) composites and its mechanical and tribological properties were studied. The aluminum alloy was reinforced with 3, 6, and 9 wt% of palmyra shell ash particles, and its dry sliding wear behavior was studied using a pin-on-disc machine under different loading conditions. The result shows that the dry sliding wear resistance of Al–palmyra shell ash composites was almost similar to that of fly ash– and rice husk ash–reinforced Al-alloy composites and these composites exhibit better wear resistance compared to unreinforced alloy. The palmyra shell ash particle weight fraction significantly affects the wear and friction properties of the composites. Scanning electron microscopic examination of the worn surface reveals that at various loads palmyra shell ash particles act as load-bearing constituents and the wear resistance of the reinforced palmyra shell ash with a size range of 1–50 µm was superior to that of unreinforced alloy. Mechanical properties (hardness and tensile strength) were also studied and it was observed that the reinforced Al-alloy showed a significant increase in mechanical properties.

Influence of machining parameters on cutting tool life while machining aluminum alloy fly ash composite

Metal matrix composites containing fly ash as reinforcement are primarily preferred because these materials possess lower density and higher strength to weight ratio. The metal matrix composites possess hetrogeneous microstructure which is due to the presence of hard ceramic particles. While turning composites, the catastrophic failure of cutting tools is attributed to the presence of hard particles. Selection of optimal cutting conditions for a given machining process and grade of cutting tools are of utmost importance to enhance the tool life during turning operation. Thus the research work was aimed at the experimental investigation of the cutting tool life while machining aluminum alloy composite containing 0-15% fly-ash. The experiments carried out following ISO3685 standards. The carbide inserts of grade K10 and style CGGN120304 were the turning tools. The cutting speed selected was between 200m/min to 500m/min in step of 100m/min, feed of 0.08 & 0.16 mm/revolution and constant depth of cut of 1.0 mm. The experimental results revealed that the performance of K10 grade carbide insert found better while machining composite containing 5% filler, at all cutting speeds and 0.08mm/revolution feed. The failures of carbide tools are mainly due to notch wear followed by built up edge and edge chipping.

Theoretical and Experimental Study of the Al – Cu – Si – Sn Phase Diagram in the Range of Aluminum Alloys

Phase compositions of aluminum alloys of the Al – Cu – Si – Sn system are studied by computational and experimental methods. The computations are performed with the use of the Thermo-Calc software; the experimental part is implemented with the use of light and scanning electron microscopy, microscopic x-ray spectrum and thermal analyses. According to the computation, the quaternary system may exhibit layering of liquid and occurrence of monotectic transformations including a five-phase nonvariant one. The solidus temperature of the quaternary alloys depends little on the presence of copper and silicon and virtually coincides with the melting temperature of pure tin. The solubility of tin in the aluminum solid solution and in the (Si) and Al2Cu phases is negligibly low. Heating at 500°C changes substantially the morphology of the tin phase.

Aerogel-filled metals: a syntactic cellular material

A new filler material is presented and tested to produce light-weight aluminium alloy composites: the pore space between nano-structured silica-aerogel granulates is infiltrated with Al-alloy melts. Since these filler materials have vanishing density (100 kg m−3), they need not to be removed from the final cast product. Their shape, size and volume fraction determine the materials' properties. Different methods were used to prepare metal-aerogel syntactic foam composites: centrifugal casting, squeeze and suction casting. The last method gave the best results, using an Al–11Si melt. We produced circular and rectangular bars up to 500-mm length. The composite material has a density of around 900 kg m−3, a yield stress of 8 MPa and absorbs 8 kJ kg−1 mechanical energy.

Graphene-reinforced aluminum matrix composites prepared by spark plasma sintering

Graphene-reinforced 7055 aluminum alloy composites with different contents of graphene were prepared by spark plasma sintering (SPS). The structure and mechanical properties of the composites were investigated. Testing results show that the hardness, compressive strength, and yield strength of the composites are improved with the addition of 1wt% graphene. A clean, strong interface is formed between the metal matrix and graphene via metallurgical bonding on atomic scale. Harmful aluminum carbide (Al4C3) is not formed during SPS processing. Further addition of graphene (above 1wt%) results in the deterioration in mechanical properties of the composites. The agglomeration of graphene plates is exacerbated with increasing graphene content, which is the main reason for this deterioration.

Influence of pretreatment of SiC on microstructure and properties of SiCp/A390

In this paper, two pretreatment methods of silicon carbide (SiC) particles were adopted: washing by hydrochloric acid (HCl) and high-temperature oxidation after washing by hydrochloric acid. The powder metallurgy method was used for better controllability of the prepared particles of the silicon carbide-reinforced aluminium alloy composites of A390. The changes in the morphology and composition of the silicon carbide particles after different pretreatment methods were studied; at the same time, the effects of the different pretreatment methods on the microstructure and mechanical properties of the composites were analysed. Research shows that washing by hydrochloric acid of the silicon carbide particles is mainly for cleaning, and high-temperature oxidation of the silicon carbide particles after washing by hydrochloric acid is mainly for producing a passivation effect, producing silicon dioxide. The high-temperature oxidation of the silicon carbide particles in the composites leads to the following: the particles distribute well; the interface bonding density improves; the resulting composites are without holes; the tensile strength and the relative density of A390 composites, reinforced by silicon carbide particles, after oxidation treatment, increased by 36% and 2·64%, respectively, compared to those of the original state of the silicon carbide particle-reinforced composites of A390.

Impacto da pureza dos filtros de alumínio no valor de Camada Semi-Redutora em radiologia convencional e mamografia

Half Value Layer (HVL) test is an important technical information in conventional radiology once it is the only test which allows us to quantify beam quality in a complete way. This work promotes a preliminary analysis of the impact of aluminum alloy composition in the determination of HVL value taking into account a realistic geometry. Deterministic calculations and Monte Carlo Method were applied in order to make the proposed analysis. Six aluminum alloys (99% pure) commercialized and pure aluminum were used as comparative basis for both methods. Experimental data were collected in conventional radiology, using tungsten target and aluminum filter for two peak tensions (66 kVp, 81 kVp), and in mammography, using three target filter combinations( molybdenum-molybdenum, molybdenum-rhodium, tungsten-rhodium) for three peak tensions (25 kVp, 30 kVp and 35 kVp). Spectra used in the deterministic calculations were taken from Report No 78 of Institute of Physics and Engineering in Medicine, 1997. Results show that Mammography is more sensitive than conventional X-ray equipment to impurities in aluminum alloys (up to 34.65% variation for W-Rh combination with 30 kVp).