Microstructure Of Aluminum Alloy Research Articles

Microstructure and tensile strength of AC8A aluminum alloy fabricated by laser-based powder bed fusion and electron-based powder bed fusion

Microstructure and tensile strength of AC8A aluminum alloy fabricated by laser-based powder bed fusion and electron-based powder bed fusion

Effects of cryogenic deformation on the microstructure and mechanical properties of high-strength aluminum alloys

7A85 aluminum alloy forgings were compressed at 10% to 30% deformation at room and cryogenic temperatures, followed by solid-solution treatment, water quenching, 3% cold deformation, and two-stage aging. The results indicated that cryogenic deformation increased coarse second-phase particle fragmentation and led to massive dislocation proliferation, which facilitated particle dissolution due to the formation of more interfaces and dislocation-promoted dissolution. These increased the driving force for aging precipitation and produced denser matrix precipitates and narrower grain boundary precipitate-free zones. Meanwhile, numerous dislocations provided more nucleation sites for recrystallization and thus refined grains during solution treatment. The grains were refined from 500 μm in the undeformed state to an average size of 35 μm under 20% cryogenic deformation. The excessive dislocation energy and stored deformation energy at 30% deformation caused recrystallized grain growth. The optimal mechanical properties were obtained at 20% cryogenic deformation with an ultimate tensile strength, yield strength, and elongation of 499 MPa, 435 MPa, and 13.1%, which were respectively 1.6%, 2.1%, and 37.9% higher than those of the undeformed sample. • Uniformly fine equiaxed grains and the best elongation were obtained at 20% cryogenic deformation. • Excessive dislocation energy and stored deformation energy at 30% deformation led to recrystallized grain growth. • Increasing the deformation and decreasing the temperature resulted in denser matrix precipitates. • Increasing the deformation and decreasing the temperature resulted in narrower grain boundary PFZs.

Microstructure and mechanical properties of 2A12 aluminum alloy welded joint through CMT double side welding

In this work, the cold metal transfer (CMT) double side welding was carried out to weld 2A12 aluminum alloy plate. The influence of the heat input on the weld appearance was studied, which indicated that when the heat input was exceeded to 651.75 J/mm the better weld appearance was obtained. Through the scanning electron microscope (SEM), electron back-scatter diffraction (EBSD) and tensile testing, the microstructure and mechanical properties of welded joints were investigated. The results showed that the size of microstructure in the front weld seam was less than that of the back weld seam due to the secondary thermal cycle. With the increases of heat input, the average grain size and elongation of welded joints were increased, the tensile strength of welded joints was reduced. The strength coefficient of welded joint was about 70%. The fracture model of welded joint belonged to ductile fracture.

Effects of Cow Horn Particulates as Addictive on Microstructure, Tensile and Compressive Properties of Recycled Aluminium Alloy

In the recent time, the development of low cost metal alloys reinforced with waste materials such as agricultural waste and industrial waste has been one of the major innovations in the area of material science. Aluminium scraps were used as raw material and reinforced with locally available inexpensive cow horn particulate (CHp) of 3, 6, 9 and 12% by weight to develop a new material in the present study. The microstructure view was studied using optical microscope for analysing the distribution of CHp. The tensile and compressive strengths were studied for the reinforced CHp aluminium alloy. The results revealed that the tensile and compressive strengths values increase as the CHp increases and falls when the weight proportion reaches 12% due to poor wettability. Increment of 10.1%, 19.2%, 29.4% and 8.7% in tensile strength and 13.3%, 31.2%, 43.2% and 12.7% in the compressive strength were recorded for addition of 3%, 6%, 9% and 12% CHp reinforcement, respectively. The microstructure examination shows that the control sample contained fine, packed and shining grained structure while the CHp reinforced aluminium alloy contained less packed, dull with some inclusion grained structure. The inclusion and dull surface of the grains was observed increases as the percentages of the cow horn particles added increased. The spectrographic analysis conducted to determine the chemical compositions of all the specimens, showed various elements present in control sample and CHp reinforced aluminium alloy. Aluminium is in the range 91.3-93.0%, followed by silicon with 4.36-5.01%, other elements present include iron, copper, magnesium, manganese, chromium, nickel, zinc, titanium, lead, and others.

Microstructure, Properties, and Numerical Simulation of Semi-Solid Aluminum Alloy under Planetary Stirring Process

In order to solve the problem of insufficient convective heat transfer of uniaxial stirred melt, the temperature field and shear rate of melt under planetary stirring were studied based on CFD simulation. The microstructure and properties of this technology were also experimentally studied. The results show that compared with the uniaxial stirring semi-solid technology, the convective heat transfer ability of aluminum alloy, semi-solid slurry in planetary stirring mode is stronger. In addition, its temperature field can be reduced to the semi-solid range faster and more evenly, which is conducive to a large number of nucleation and improves the nucleation rate. The temperature difference of the whole melt is small, so the preferred direction growth and uniform growth of dendrites are avoided, and the morphology is improved. Properly increasing the revolution and rotation speed of the stirring shaft can refine the grains of semi-solid aluminum alloy parts, improve the grain morphology, and improve the tensile strength. The planetary stirring semi-solid process is very suitable for rheological high-pressure casting.

Alloying effect of copper in AA-7075 aluminum composite using bale out furnace

This study investigated the effect of copper addition on AA-7075 aluminum alloy's microstructure and mechanical behavior. Aluminum alloy with copper reinforcement varying between 0.3 and 0.7 wt.% was produced using the stir casting technique. The cast aluminum alloy was pre-heated at a temperature of 300 °C and held for 1 h before charging into the bale-out furnace. Two AA-7075 + Cu alloy samples were produced at a different weight percent of copper. Both pre-heated and the as-received aluminum samples were subjected to mechanical testing after machining. The surface morphology of the samples was studied using optical and scanning electron microscopy. The relevance of the percentage weight of copper in the aluminum alloy cannot be over-emphasized and strategic in the food processing and packaging industries. The result showed that the higher the addition of Cu the harder the composite becomes. The microstructures showed distinct grain boundaries for AA-7075 aluminum alloy while rich regions of silicon saturation were observed for 0.7 wt.% Cu in AA-7075 and 0.3 wt.% Cu in AA-7075 alloy. The AA-7075 alloy samples with 0.7 wt.% copper and 0.3 wt.% copper had their respective tensile strength as 0.18 Mpa and 0.15 Mpa and hardness value as 420Hv1 and 240HVv1. The tensile strength of the cast samples was positively influenced by the addition of copper with well-distributed reinforcing intermetallic phases which are fine grain size, although there is an observable reduction of micro-segregation. Thus, enhancing the mechanical properties of the alloys of the developed composites.

Effect of preheat & post-weld heat treatment on the microstructure and mechanical properties of 6061-T6 aluminum alloy welded sheets

MIG welding is one of the most predominantly welding techniques in manufactories due to its high automation. However, aluminum alloy welded joints fabricated using MIG welding often exhibit a reduction in mechanical properties. In this paper, an attempt has been made to combine preheat and post-weld aging treatment in double-pulse MIG (DP-MIG) welding process to produce 6061-T6 aluminum alloy welded sheets with high mechanical properties. Response surface methodology (RSM) was used to study the main effect and interactive effect of heat treatment parameters including preheat temperature, aging temperature and time on mechanical properties. On this basis, the optimum heat treat parameters that maximize both strength and ductility of welded joints have been determined using multi-objective optimization algorithm. Additionally, the influence of heat treatment parameters on the microstructural evolution and mechanical properties of welded joints was further investigated, by systematic experimental and theoretical analysis. The results showed the preheat temperature affects the grain size and precipitation of the welded joint, while the aging heat treatment mainly affects the precipitation and transformation of the strengthen phase. Since the aging temperature is of greater significance for the improvement of mechanical properties of welded joints, compared with other heat treatment parameters and their interactions, indicating the strengthening of precipitates determines the mechanical properties of welded joints.

Effects of Heat Treatment on the Microstructure and Properties of Graded-Density Powder Aluminum Alloys

Effects of Heat Treatment on the Microstructure and Properties of Graded-Density Powder Aluminum Alloys

Microstructure, mechanical properties, and crack formation of aluminum alloy 6063 produced via laser powder bed fusion

Microstructure, mechanical properties, and crack formation of aluminum alloy 6063 produced via laser powder bed fusion

Effect of melt pouring rate and height on solidification, microstructure and mechanical properties of A356 aluminium alloy casted via cooling slope

ABSTRACT Experimental investigations encompass the effect of melt pouring rate and melt pouring height on solidification, microstructure and mechanical properties of A356 aluminium alloy aimed at semisolid casting via cooling slope. Melt pouring rate with melt pouring height ensure about necessary amount of solidification with required shear for generating semisolid slurry. Moderate melt pouring rate of 0.025 kg s−1 with melt pouring height of 0.2 m brings quite a modest solidification which would absolutely contribute toward enhanced overall (microstructural/mechanical) properties aimed at semisolid casting. Because pretty smaller melt pouring rate/height would cause less shearing, however, bigger melt pouring rate/height has a coarsening effect (which opposes grain refinement) resulting from coalescence/agglomeration of neighbouring dendrite arms and Ostwald ripening owing to increasing diffusion in liquid. It results in inferior overall (microstructural/mechanical) properties with exceedingly undesirable and adverse challenges in semisolid casting. As, during treatment escaping/retaining of gases, waste metals alongside alloy elements occurs. Because smaller melt pouring rate/height lets alloy elements escape hence decreases strength and vice-versa. Furthermore, smaller melt pouring rate/height also lets gases alongside waste metals escape hence enhances strength and vice-versa. Hence, moderate parameter intensities for semisolid casting ensure solution to perplexity.

Microstructure and age-hardening effects of aluminium alloys with additions of scandium and zirconium

Abstract The aim of the work presented in this report was to produce age-hardenable aluminium alloys containing scandium and zirconium by a casting process with similar cooling conditions like an industrial casting process. Microstructure, precipitation structure and age-hardening response of different alloys with up to 0.4 wt.% Sc and Zr were investigated. Age-hardening experiments from the as-cast condition without solution annealing showed a significant increase of hardness of about 100% for Sc-rich alloys and of 50% for Zr-rich alloys compared to the as-cast condition. TEM investigations revealed the formation of precipitates of ternary Al3(Sc x Zr1–x) phases with a cubic cP4 crystal structure. In addition to the strengthening effect, a high thermal stability especially of the precipitates in Zr-rich alloys up to 400 °C let these alloys look very promising for high-temperature applications.

Texture and intermetallic compounds of the Cu/Al dissimilar joints by high power ultrasonic welding

The welded joints of copper (Cu) to aluminum (Al) were increasingly being used for electric vehicle battery applications. To better understanding the interface connection mechanism of the Cu/Al joints produced by high power ultrasonic welding (HUSW), the texture and intermetallic compounds of Cu/Al HUSW joints were systematically investigated. The grain morphology and size of pure copper along welding interface had little change with the increasing welding time, whereas the microstructure of aluminum alloy changed from elongated grains to equiaxed grains and the grain size increased rapidly at the welding time from 0.3 s to 0.5 s. The texture intensity of both copper and aluminum alloy decreased at first owing to ultrasonic softening and then increased due to the shear work hardening. The texture type of the copper had little change, whereas the gaussian texture {110}〈110〉 and the cubic rotation texture{001}〈110〉 were formed in aluminum alloy owing to the occurrence of recrystallization driven by the severe shear deformation. The formation mechanism and accelerated growth behavior of intermetallic compounds at the welding interface during HUSW were discussed based on the atom rapid diffusion and the effective thermal formation model.

Review on Micro-Alloying and Preparation Method of 7xxx Series Aluminum Alloys: Progresses and Prospects

Notably, 7xxx series aluminum alloy has become the most popular nonferrous alloy, extensively used in industry, construction and transportation trades, due to its high comprehensive properties such as high static strength, high strength, heat resistance, high toughness, damage resistance, low density, low quenching sensitivity and rich resource. The biggest challenge for aluminum alloy today is to greatly improve the corrosion resistance of the alloy, while maintaining its strength. The preparation method of 7xxx series aluminum alloy requires controlling time lapses in the process of heating, holding and cooling, and there are many species precipitates in the crystal, but the precipitated strengthening phase is a single type of equilibrium η′ phase. Therefore, more attention should be paid to how to increase the volume fraction of η′ precipitates and modify the comprehensive performance of the material and focus more on the microstructure of the precipitates. This article reviews the progress of 7xxx series aluminum alloy materials in micro-alloying, aging precipitation sequence, the strengthening-toughening mechanism and the preparation method. The effect of adding trace elements to the microstructure and properties of 7xxx series aluminum alloy and the problems existing in aging precipitation characteristics and the reinforcement mechanism are discussed. The future development direction of 7xxx series aluminum alloy is predicted by developing a method for the process-microstructure-property correlation of materials to explore the characteristic microstructure, micro-alloying, controlling alloy microstructure and optimizing heat-treatment technology.

Effects of process parameters on microstructure and properties of aluminum alloy fabricated by friction extrusion additive manufacturing

Effects of process parameters on microstructure and properties of aluminum alloy fabricated by friction extrusion additive manufacturing

The structure of rapidly solidified foil of Al – Bi alloys

The results of study of the microstructure and texture of aluminum alloys, containing 0.12 and 0.25 at. % Bi, obtained with high-speed solidification, are presented (melt cooling rate liquid – not less 105 K /s). Texture (111) aluminum is formed in the rapidly solidified foils of investigated alloys and it is conserved under annealing at 523 K during 2 h. The average chord of bismuth sections does not exceed 0.05 µm. As the crystallisation front moves from surface A contacted with crystalliser to the surface B, the average size of dispersed bismuth particles increases. Foils of the alloys dissolve in water at room temperature actively forming hydrogen bubbles in vessel with water, white powder of aluminum oxide in an amorphous state and bismuth precipitations. Isotermical annealing of foils at 573 K for 5 h causes a change in distribution of chords in size groups and increases their average value. After the annealing bismuth particles are localised on low- and high-angle boundaries. The rapidly solidified foils of Al – Bi system can be used to produced hydrogen, aluminum oxide powder and create technical devices using hydrogen.

Influence of the rotation speed on the interface microstructure and joining quality of aluminum alloy 6061/CF-PPS joints produced by refill friction stir spot welding

Influence of the rotation speed on the interface microstructure and joining quality of aluminum alloy 6061/CF-PPS joints produced by refill friction stir spot welding

Microstructure, Mechanical and Wear Properties of Low-Density Cast Medium and High Entropy Aluminium Alloys

Microstructure, Mechanical and Wear Properties of Low-Density Cast Medium and High Entropy Aluminium Alloys

Effect of quenching on post-processed aluminum 6082 alloy using friction stir processing

Recently, experimentation on cooling media alteration during Friction Stir Processing (FSP) had put impetus efforts to analyzing the effects on microstructures of Aluminum alloys. On the other hand, developing alternative cooling processes like the artificial aging of post-processed FSPed components is also seized the consideration to study the grain refinement of Al-Alloys. This work focuses on studying the effects of oil quenching on FSPed Al 6082 alloy after completing the conventional procedure. Unconventional to the air cooling and water cooling during the machining process, the post-processed Al 6082 alloy (PPA) was submerged for two hours in an oil bath, and effects on microstructure, microhardness, and tensile strength were compared with conventional cooling media. The increments that occurred in microhardness and tensile strength revealed that the PPA had gained mechanical strength after oil quenching. Subsequently, PPA’s microstructure became coarser unlike the conventional characteristic of the FSPed specimen.

Microstructure, strength and welding window of aluminum alloy−stainless steel explosive cladding with different interlayers

Aluminum 5052 (Al 5052)−stainless steel 316 (SS 316) plates were explosively cladded with Al 1100, pure copper and SS 304 interlayers. The operational parameters viz., standoff distance, explosive mass ratio (mass ratio of the explosive to the flyer plate) and inclination angle were varied and the results were presented. The advent of interlayer relocates the lower boundary of the welding window, and enhances the welding regime by 40%. A triaxial welding window, considering the influence of the third operational parameter, was developed as well. Use of interlayer transforms the continuous molten layer formed in the traditional Al 5052−SS 316 explosive clad interfaces into a smooth interface devoid or with a slender presence of intermetallic compounds. The microhardness, ram tensile and shear strengths of the interlayered clads are higher than those of the traditional explosive clads, and the maximum values are witnessed for stainless steel interlaced Al 5052−SS 316 explosive clads.

Investigation of the microstructure and mechanical properties of AA6063 and AA7075 dissimilar aluminium alloys by friction stir welding process

Friction stir welding (FSW) is one of the advanced welding processes to join both similar and dissimilar alloys and materials. The FSW process is most widely used in automotive, aerospace, and nautical industries to join similar and dissimilar aluminum alloys. In this research work, two dissimilar aluminum alloys of AA6063 and AA7075 were joined using the friction stir welding process and characteristics of the welded joint were studied. Friction stir welded joints of dissimilar alloys were studied by varying the input process parameters of tool rotating speed of 800, 1000 to 1200 rpm with varied the welding speed of 30 to 60 mm/min. The influence of varying the input parameters was studied by the mechanical properties of the friction stir welded (FSW) specimen and the microstructure were analyzed using SEM images.