Microstructure Of Aluminum Alloy Research Articles

Effect of Trace Yttrium Addition and Heat Treatment on the Microstructure and Mechanical Properties of As-Cast ADC12 Aluminum Alloy

The effects of rare earth yttrium (Y) additions and the heat treatment process on the microstructure and mechanical properties of as-cast ADC12 aluminum alloy have been investigated. The results showed that the primary Si crystals were significantly refined from long axis to fibrous or granular when the Y content was 0.2 wt%. Compared to the matrix, the mean area and aspect ratio were decreased by 92% and 75%, respectively. Moreover, the Si and Fe-rich phases were spheroidized and refined with a small average size during the solid solution. It was also noted that the copper-rich phases were dissolved into the matrix. Correspondingly, it was found that after metamorphic and heat treatment the ultimate tensile strength (UTS), elongation, and, hardness increased by 81.9%, 69.7%, and 74.8%, respectively, compared to the matrix. The improved mechanical properties can primarily be attributed to the optimization of the microstructure and the refinement of various phases.

Effects of CeO2 on the microstructure and properties of 2A12 porous aluminum

The micron porous aluminum has received considerable attention in various domains, and the research of rare earths for the synthesis of materials with improved mechanical performance. In the present work, 2A12 aluminum alloys with different porosities were successfully prepared by cold pressing-vacuum sintering-dissolution process (SDP) with the CeO2 additive, and the CeO2 content effect on the microstructure and mechanical properties of the porous aluminum alloys were investigated. The results show that the open-cell porous aluminum with uniform holes can be obtained by SDP. CeO2 addition affects the microstructure of porous aluminum alloys and results in the formation of Al11Ce3 phase in specimens, which can enhance mechanical properties of the alloys. With increasing content of CeO2, all the specimens have a trend of increasing first and then decreasing, and when the CeO2 content equal to 0.2 wt%, the tensile and compression strengths of porous aluminum with different porosities achieved the maximum value.

Vpliv temperature deformacije na mikrostrukturo in mehanske lastnosti Al zlitine AA3003

Vpliv temperature deformacije na mikrostrukturo in mehanske lastnosti Al zlitine AA3003

Vpliv procesnih parametrov na mikrostrukturo in lastnosti Al zlitine ZL116 po vakuumskem litju

Vpliv procesnih parametrov na mikrostrukturo in lastnosti Al zlitine ZL116 po vakuumskem litju

Effects of micro flexible rolling and annealing on microstructure, microhardness and texture of aluminium alloy

The microstructure and texture after plastic deformation are strongly dependent on the corresponding manufacturing process and subsequent annealing which significantly affect the properties of the final products. In this study, 1060 aluminium alloy with a thickness of 464 μm was micro flexibly rolled to a constant thickness ratio of 3.6 by a combined control of the roll gap, the rolling speed and the roll lifting speed. Afterwards, the rolled specimens were subjected to isochronal annealing at a temperature range of 200 to 400 °C for 30 min and isothermal annealing at 400 °C for 10–60 min. Results indicate that the microstructure, microhardness and texture of each thickness zone are distinctly influenced by the rolling parameters and annealing conditions. Specimens annealed at 400 °C for 30 min result in a relatively steady hardness distribution along the transition zones. Typical β fibre texture is observed in the specimens suffered from annealing while S is predominant in both micro flexibly rolled and annealed specimens.

Synergistic Effect of Sr and Ca Combined Additions on the Microstructure of A390 Aluminum Alloy

Effects of Sr and Ca combined additions (Sr+Ca=0.05wt/%) on the microstructure of A390 aluminum alloy were evaluated by investigating the variation of quantity, size and shape of primary silicon, eutectic silicon, primary α phase and intermetallic phase. The results show that the variation of microstructures results from the synergistic effect of Sr-Ca additions. The loss rate of Sr is reduced with a small amount of Ca; meanwhile, the coarsening effect of primary silicon phase arising from Sr addition is also suppressed. The Sr in A390 aluminum alloy mainly modifies eutectic silicon phase and refines θ phase. Furthermore, Ca principally modifies primary silicon phase and primary α phase. The optimal microstructure is obtained when combined addition of 0.05%Sr-Ca is applied and the atomic ratio of Sr and Ca is 5:1, in which primary silicon phase and eutectic silicon phase as well as primary α phase are all modified significantly compared with those of only 0.05% Sr addition.

Effect of Friction Stir Processing on the Microstructure and Mechanical Properties of A384 Aluminum Alloy

Friction stir processing (FSP) is a solid-state technique for microstructural modification. The aim of this work is to evaluate the effect of input process parameters of friction stir processing (tool rotational speed rpm, travel speed mm/min) on microstructure and mechanical properties of A384 aluminum alloy. A384 aluminum alloy was cast using conventional stir casting process. The obtained alloy was subjected to friction stir process using different input parameters (rpm, mm/min) with double pass. Water was used as cooling medium during process. The microstructures of investigated alloys were characterized by optical, SEM microscopes, EDS and Map analyzer, while mechanical properties were evaluated by using tensile test. The results indicate that; after friction stir processing, the microstructure of as-cast alloy was greatly improved. Needle-like eutectic Si and Chinese Script a-Fe were modified to fine precipitates. Meanwhile, coarse primary Si and large plate b-Fe phase were dissolved. On the other hand, mapping analysis shows homogenous distribution of different alloying elements through the matrix. The higher values of tensile properties were obtained at 1200 rpm and 80 mm/min. UTS and YS were increased by 98% and50%, respectively. Meanwhile, ductility was approximately three times higher than that of cast alloy.

The Effects of Low Frequency on the Microstructure and Mechanical Properties of High-Strength Al-Mg Aluminum Alloys by Wire and Double-Pulsed Arc Additive Manufacturing

An innovative and high deposition efficiency process, the double-pulsed arc additive manufacturing process, is used to produce high-strength Al-Mg wall components. This dissertation investigates the electrical parameter acquisition, bead appearance, porosity morphology, microstructure and mechanical properties of additively manufactured high-strength Al-Mg wall components and how these are affected by the low frequency of the double-pulsed arc additive manufacturing process. Then, using this process at different low frequencies of 0, 1, 3, 5, 7 and 9 Hz, multilayer deposition experiments were performed. It can be observed that the deposit porosity is obviously eliminated compared with cold metal transfer (CMT) process. The bead appearance of the deposited aluminum wall varies clearly with low frequencies, and at a low frequency of 3 Hz, its appearance is the best of all. The optical observation of microstructure proves that the average grain size varies significantly with low frequency, and at a low frequency of 1 Hz, it is the smallest. In addition, the deposited wall showed maximum mean microhardness and maximum ultimate tensile strength at a low frequency of 3 Hz. Considering the deposited porosity and mechanical priorities, double-pulsed arc additive manufacturing with a frequency of 3 Hz is more suitable for making high-strength Al-Mg wall components than at other low frequencies.

Effects of Holmium Additions on Microstructure and Properties of A356 Aluminum Alloys

Sr-modification of A356 alloys has distinct shortages due to the volatilization and oxidation during remelting and pouring, which often reduce the modification efficiency and mechanical properties of the alloys. To avoid the adverse effects and enhance the comprehensive properties, the effects of heavy rare earth element holmium (Ho) modification on the microstructure and properties of the alloy were investigated. Ho addition inhibited the intrinsic orientation growth of (111)Al planes and stimulated the growth of the (200)Al planes for α-Al crystals. The addition of 0.2 wt.% Ho produced the best refinement effect for α-Al grains; 0.3 wt.% of Ho addition yielded the most distinct modification effect for eutectic Si phases, which was further improved by a T6 treatment. The extra addition of 0.4 wt.% Ho resulted in the complete loss of the refinement and modification effects and in the abnormal growth of the α-Al crystals. Ho additions produced Al3Ho phases containing Fe elements, which were distributed on the boundaries of the α-Al dendrites. The corrosion-proof performance was enhanced by Ho addition and the T6 treatment; the tensile strength and elongation achieved the highest value upon 0.2 wt.% of Ho addition and the T6 treatment. Moreover, the hardness was also enhanced by Ho additions in both states.

Microstructure of High-Performance Aluminum Alloy Surface Processed by the Single-Excitation Same-Frequency Longitudinal⁻Torsional Coupled Ultrasonic Vibration Milling.

The high performance of parts is determined by the microstructure of the machined surface to some extent. Different processing methods have been used to construct different microstructures on machined surfaces; the effective improvement of the serviceability of parts has been the focus of research in the field of precision and ultra-precision machining. In the presented work, a microscratch was formed on the machined surface in ultrasonic assisted machining, and the surface microstructure of high-performance aluminum alloy processed by single-excitation rotational longitudinal–torsional coupled ultrasonic vibration (LTCUV) milling was investigated. First, the motion paths model of the cutting edge in the LTCUV milling were established; then, the single-excitation LTCUV milling system has been set up, and the acoustic performance of the LTCUV system was examined. The surface microstructure of aluminum alloy was processed by different machining techniques, and the effect of processing parameters on the surface microstructure and performance were investigated by the orthogonal design of experiment (DOE). The surface roughness was found to be proportional to the ultrasonic cutting speed and feeding rate. The surface roughness was mainly controlled by the ultrasonic amplitude, and the optimal surface quality corresponded to the ultrasonic amplitude of 4 μm. The cutting speed contributes greatly to the surface roughness. The water contact angle of surfaces obtained by ultrasonic processing was larger than that of surfaces achieved by the conventional processing, while the surface water contact angle was negatively related to the ultrasonic amplitude. Once the rotation speed exceeded a critical level, the ultrasonic amplitude exerted a negligible effect on the surface water contact angle. The cutting speed contributes the most to the water contact angle. The friction coefficients of surfaces treated by ultrasonic processing were lower than those obtained by conventional processing at constant processing parameters, while the friction coefficient was minimized at the ultrasonic amplitude of 4 μm. In the case of grease lubrication friction, the surface wear decreased with the ultrasonic amplitude, indicating the improved wear resistance of the processed surfaces. Similarly, the ultrasonic amplitude has the highest contribution rate to friction and wear.

Microstructure and strength of a novel heat-resistant aluminum alloy strengthened by T-Al6Mg11Zn11 phase at elevated temperatures

We designed an aluminum (Al)-based alloy with the α-Al (fcc) matrix strengthened by the T-Al6Mg11Zn11 (cubic) intermetallic phase using a large two-phase region of α and T phases in the Al–Mg–Zn ternary system. Thermodynamic analysis assessed a composition of Al–5Mg–3.5Zn (at%) with the α-Al phase reinforced with high fractions (approximately 10%) of T phase. We observed that the T phase preferentially precipitated at grain boundaries in the α-Al matrix, increasing the area fraction of the T phase at grain boundaries during aging. The granular precipitates of the T phase were dispersed rather homogenously in the α-Al matrix with a particular orientation relationship of (1−11)α // (1−21)T and [011]α // [111]T at temperatures above 300 °C. After aging at 200 °C, numerous fine precipitates with a mean size of ~20 nm in the grain interior were observed, which were likely the metastable phase associated with the T phase. The present alloy (pre-aged at 200 °C for 1 h) exhibited a high yield strength of approximately 260 MPa at 200 °C, much higher than those of the conventional Al alloys at elevated temperatures corresponding to service temperatures for compressor impellers in turbochargers.

Vpliv načina obdelave taline na mikrostrukturo in mehanske lastnosti aluminijeve zlitine AA3003

Vpliv načina obdelave taline na mikrostrukturo in mehanske lastnosti aluminijeve zlitine AA3003

Temperature Evolution, Microstructure and Mechanical Properties of Heat-Treatable Aluminum Alloy Welded by Friction Stir Welding: Comparison with Tungsten Inert Gas

Temperature Evolution, Microstructure and Mechanical Properties of Heat-Treatable Aluminum Alloy Welded by Friction Stir Welding: Comparison with Tungsten Inert Gas

Effect of Superheat Melt Treatment on Microstructure and Mechanical Properties of Aluminum Alloys Produced by Lost Foam Casting

The resource-saving technology for producing of thin-walled castings from A356.1, A413.1 and A360.0 aluminum alloys by the lost foam casting method, as well as the results of this technology implementation in production conditions are considered in the paper. The technology involves thermo-speed treatment of the melt with the predominance of secondary materials in charge (85...90 wt.%), including isothermal holding and subsequent rapid cooling of the melt for fixation the high-temperature state. It is shown that the use of thermo-speed treatment promotes the production of aluminum castings with fine-grained microstructure and the enhanced level of mechanical properties without the addition of costly modifying additives, and makes it possible to use an increased amount of secondary charge materials during smelting.

Effect of FSW on the mechanical properties and microstructure of 6082-T6 AA

This paper reports the effect of Friction Stir Welding on the mechanical properties and microstructure of 6082-T6 Aluminium alloy. The welds were produced using three different transverse speeds of 90, 120 and 150 m/min to vary the heat input into the wields. The rotational speed of 750 rpm is constant for the three welds samples, plunge depth of 0.31 mm and tool tilt angle of 3 degrees was employed. The mechanical properties were characterised by the tensile analysis, the microhardness and joint efficiency of the welded interface. The microstructures, macrostructures, fracture surface and grain sizes were characterised. The result revealed that tensile strength at the joint interfaces of the three samples was enhanced as the transverse speed increases from 90 m/min to 150 m/min. The joint efficiency of the joint interfaces of the three welded samples increases. The Vickers hardness values at the joint interfaces were enhanced for the three samples when compared with the base material. This is attributed to the strain hardening phenomenon. The resulting microstructural characterization shows that good metallurgical bonding was achieved at the joint interfaces of the welds produced, this is evident with the presence of the transition lines separating the advancing side from the retreating side of the joint interfaces.

Effects of rotation speed of assisted shoulder on microstructure and mechanical properties of 6061-T6 aluminum alloy by dual-rotation friction stir welding

By adjusting the rotation speed of separated pin and assisted shoulder, dual-rotation friction stir welding can reduce the softened region and improve the properties of joint. In this study, a tool system for dual-rotation friction stir welding was designed. Five-millimeter-thick 6061-T6 aluminum alloy was welded using the self-designed tool system. The effects of rotation speed of assisted shoulder on microstructure and mechanical properties of joints were analyzed. Defect-free joints were obtained under the process parameters used. Fine equiaxed recrystallized grains were found in both weld nugget zone and shoulder affected zone, while the grain size in shoulder affected zone appeared to be much smaller. The microhardness showed a noticeable decline in the weld zone, and the lowest value was located in heat-affected zone. Tensile test results demonstrated that all welded joints fractured at the interface of thermo-mechanically affected zone and heat-affected zone with ductile fracture mode.

Investigation of the effects of Mg amount on microstructure and wear behavior of Al-Si-Mg alloys

In this study, the effect of the Mg amount on microstructure and wear behaviors of A356 cast aluminum alloys is investigated. Al-Si-Mg alloys containing different amounts of Mg were produced by casting. The alloys were then aged at 170 °C for 10 h (T6). After T6 heat treatment, the samples were prepared for microstructure examinations and wear testing. Wear tests were performed with a pin-on-disc type wear testing device. Results of the study show that the hardness increases and the density decreases as the Mg fraction increases in the alloy. As a result of the wear test, the A356-0.43Mg alloy was found to have the highest weight loss and wear rate, whereas the A356-0.86Mg alloy has the lowest weight loss and wear rate.

Fabrication, microstructure refinement and strengthening mechanisms of nanosized SiCP/Al composites assisted ultrasonic vibration

The performances of particulate–reinforced aluminum matrix composites are strongly dependent on alloying elements, precipitates and added particulates. To reveal the sole influence mechanisms of high volume fraction of nanosized particulates on the solidification behavior, microstructure and mechanical properties of aluminum alloys, nanosized SiCP (60 nm) was incorporated into commercial pure Al at different volume fractions (i.e., 0, 1, 3, 5, 7 and 9 vol%) by stir–casting assisted ultrasonic vibration. The results reveal that a fairly uniform dispersion of nanosized SiCP throughout the matrix was achieved at a volume fraction as high as 7 vol%. Average α–Al dendritic sizes were significantly refined from 270 µm for the matrix to 90 µm in the solidified microstructure of nanocomposites. Thermal analysis during solidification indicates that the presence of nanosized SiCP increased the nucleation temperature of α–Al, whilst recalescence during solidification process disappeared. Additionally, the yield and ultimate tensile strength of the nanosized SiCP/Al composites at both ambient temperature and 453 K were remarkably improved, whilst remaining suitable fracture strain. Theoretical analysis suggests that the significant strength increments induced by nanosized SiCP at ambient temperature could be attributed to thermal mismatch strengthening, Orowan strengthening and grain refinement strengthening, while the pinning effect of nanosized SiCP could predominantly account for the strengthening effect at 453 K.

Effect of vibration of moulding on the gravity casted specimen during pouring of molten aluminium in metallic mould

Effect of vibration moulding has been carried out for different advanced cast products, such as die cast aluminum cylinder head, etc. Vibration moulding generally decreases the solidification time of the casting which is very important for the microstructure of cast aluminum alloys. In the present investigation, the effect of applying vibration of mould (i.e., made of cast iron) during pouring of aluminium alloy was analyzed. The mould meant for making tensile test specimen was tightly clamped on the vibration table, which vibrated with suitable frequency and amplitude.The characteristics including microstructure, hardness and tensile strength of the specimens made by with-vibration and without-vibration gravity casting processes were observed. The finer grain and denser microstructure were found in the material produced by vibration casting process compared to normal gravitation casting (with-out vibration) process. Ultimate tensile strength (UTS: 224 MPa) and elongation (3.23%) of the vibrated moulding specimens were significantly higher than the conventional gravity casting AlSi-10Mg alloy specimens (UTS: 129 MPa and elongation: 1.03%). The compared results showed significant improvements in the properties for the vibration gravity casting process.The problems in the common gravitation casting (without-vibration) normally faced are porosity, blow holes and leakage. However, these casting defects could be easily avoided by using vibration moulding at suitable frequency. Interestingly, the dense microstructure obtained from the microscopic study in the vibration casting process showed that the above mentioned problems can be eliminated easily.

Effect of CeO2 nanoparticles on Microstructure and Hardness of A6063 Aluminum Alloy.

Effect of CeO2 nanoparticles on Microstructure and Hardness of A6063 Aluminum Alloy.