Aluminum Solid Solution Research Articles

Influence of deformation and annealing on the structure, electrical resistance and hardness of the Al–4 %Cu–3 %Mn alloy casted in an electromagnetic crystallizer

Using computational and experimental methods, the influence of deformation-heat treatment on the structure, electrical resistance and hardness of the Al–4 %Cu–3 %Mn alloy produced by casting in an electromagnetic crystallizer was studied. It has been shown that at a cooling rate of more than 1000 K/s, the entire amount of manganese and half of the total copper content are dissolved in the aluminum solid solution, which allows, with subsequent deformation-thermal treatment, to form a structure with the maximum possible number of Al20Cu2Mn3 dispersoids, which allows achieving significant increasing heat resistance compared to known alloys of the Al–Cu–Mn system.

Study of minor Sc and Zr additions effect on silicon rich Al–Mg–Si aluminum alloy microstructure during Sc multistage thermal treatment

The study addresses the effect of multistage thermal treatment on microstructure formation of Al–Mg–Si series alloy with scandium and zirconium additions in Mg/Si = 0.3 proportion. Basic alloy AlM–Si without Sc and Zr and them modification AlMg1SiZrSc were cast. AlMgSiScZr alloy multi-stage thermal treatment included the following 4 annealing stages –550 °C 8 h + 440 °C 8 h + 500 °C 0.5 h + 180 °C 5 h. For AlMg1Si alloy it was performed following 550 °C 8 h + 180 °C 5 h practice. AlMgSiScZr microstructure was examined using scanning (SEM) and transmission (TEM) microscopy both in as-cast state and after each stage of thermal treatment, for AlMg1Si – both in as-cast state and after final thermal treatment. Coarse intermetallic particles were examined using SEM, while fine particles were examined using TEM. Besides, microhardness values were measured after various thermal treatment stages. It was found out, that coarse intermetallic compounds of Fe2Mg7Si10Al18 type are formed in both alloys during as-cast structure cooling down with such compounds partial dissolution during further thermal treatment. At the same time particles, that can be attributed either to (AlSi)3ScZr or to AlSc2Si2τ-phase, occur in inter-grain boundary of alloys with scandium-zirconium additions. No traces of scandium solid solution discontinuous decomposition have been identified during ingot cooling down. Thermal treatment during 8 h at 550 °C 8 and 8 h at 440 °C results in formation of the phase, which can represent both AlSc2Si2 and Al5SiZr2. At the same time nanoparticles (AlSi)3ScZr do not form during this thermal treatment stage. Heating to 500 °C during 30 min interval allows complete dissolution of magnesium in supersaturated aluminum solid solution. During the final stage β’’ particles (Mg5Si6), representing the major type, form in both alloys; in these conditions scandium does not produce significant effect on their formation.

Using fuzzy logic based-modeling and simulated annealing approaches to optimize the hardness distribution of 2024 aluminum alloy during precipitation hardening heat treatment cycles

The present study assesses the impact of age hardening parameters, including aging temperature, aging time, and solution time, on the ultimate hardness of heat-treated 2024 aluminum alloys. Using a numerical approach, fuzzy logic systems were utilized as a robust tool to forecast the mechanical characteristics of high copper aluminum solid solutions throughout the age hardening process. In addition, an attempt was made to use a novel simulated annealing technique to determine the optimum hardness and its corresponding process parameters to achieve the highest mechanical properties. Comparing a fuzzy logic model with experimental results obtained from the Brinell hardness test showed the accuracy and confidence of the fuzzy model in representing such properties. The optimization results indicated that the maximum hardness can be obtained with a solution aging temperature of 173.5 °C, an aging time of 19 hours, and a solution time of 58 minutes. Overall, the variation in the experimental peak hardness obtained using the optimized process parameters was the deciding factor in believing the model.

Phase Transformation of AlV55 Alloy at High Temperature

Vanadium–aluminum alloy is an important intermediate alloy for preparing aviation grade titanium alloys, and its product quality directly affects the finished product quality of titanium alloys. In this study, focusing on the problems of high powder content (19.8%) and low product yield in AlV55 alloy products, we conduct research on alloy quality control technology and implement a vanadium–aluminum alloy cooling crystallization control process. The research results indicate that there are three phases in AlV55 alloy, namely Al8V5, AlV, and Al2V3 phases. As the temperature decreases, the AlV phase gradually decomposes into Al8V5 phase and Al2V3 phase, and the proportion of Al8V5 phase is positively correlated with the fineness. Rapid cooling can reduce the formation of Al8V5 phase. The experimental results show that high-temperature water quenching can increase the proportion of vanadium–aluminum solid solution phase in the alloy from 19.03% to 31.76%, and reduce the fine powder rate to 13.2%, providing important product quality control means and technical support for the production of vanadium–aluminum alloys.

Combined effect of nanocompositing and addition of interlayer on friction stir welding of aluminum/magnesium joint: a study

ABSTRACT Aluminum and magnesium were welded by friction stir welding while Zinc was used as interlayer and Titanium carbide nanoparticles were applied as reinforcement. The microstructure examination and phase constitution of interfacial zones showed that the base materials reaction successfully proceeded. The changes in heat input and stir action had a very significant effect on microstructural development, the distribution of nanoparticles, wettability at the interface, and intermetallic compound formation (Al3Mg2 and Al12Mg17). Aluminum solid solution, MgZn2, Magnesium/Aluminum/Zinc Intermetallic Compounds and Magnesium were the much important Compounds in the nugget zone. The best joint with the highest tensile strength and elongation percentage of 182 MPa and 1.5%, respectively, was made at transverse speed of 45 mm/min and rotation speed of 750 rpm with presence of Titanium carbide particles and Zinc interlayer material. Meanwhile, the hardness of 185 Hv with relative ductile fracture was detected for the optimized weld sample.

Microstructure and Phase Composition of Novel Crossover Al-Zn-Mg-Cu-Zr-Y(Er) Alloys with Equal Zn/Mg/Cu Ratio and Cr Addition

The effect of 0.2%Cr addition on the structure, phase composition, and mechanical properties of the novel cast and wrought Al-2.5Zn-2.5Mg-2.5Cu-0.2Zr-Er(Y) alloys were investigated in detail. Chromium is distributed between primary crystals (5.7–6.8%) of the intermetallic phase and the aluminum solid solution (0.2%) (Al). The primary crystals contain for the main part Cr, Ti, Er(Y). The experimental phase composition is in good correlation with the thermodynamic computation data. The micron-sized solidification origin phases (Al8Cu4Er(or Y) and Mg2Si) and supersaturated (Al) with nano-sized Al3(Zr,Ti) and E (Al18Mg3Cr2) precipitates are presented in the microstructure of the novel alloys after solution treatment. The nucleation of η (MgZn2) (0.5%), S (Al2CuMg) (0.4%), and T (Al,Zn,Mg,Cu) (8.8%) phase precipitates at 180 °C, providing the achievement of a maximum hardness of 135 HV in the Al2.5Zn2.5Mg2.5CuYCr alloy. The corrosion potential of the novel alloy is similar to the Ecor of the referenced alloy, but the corrosion current density (0.68–0.98 µA/sm2) is still significantly lower due to the formation of E (Al18Mg3Cr2) precipitates and S phase precipitates of the aging origin, in addition to the T phase. The formation of E (Al18Mg3Cr2) precipitates under the solution treatment provides a lower proportion of recrystallized grains (2.5–5% vs. 22.4–25.1%) and higher hardness (110 HV vs. 85–95 HV) in the Cr-rich alloys compared to the referenced alloys. Solution treated, hot and cold rolled, recrystallized, water quenched and aged at 210 °C alloys demonstrate an excellent microstructure stability and tensile properties: YS = 299–300 MPa, UTS = 406–414 MPa, and El. = 9–12.3%.

Intermetallic compounds in equilibrium with aluminum in Al–Ca–Cu ternary alloying system

The structure and properties of the new (Al,Cu)4Ca, Al27Ca3Cu7, and Al8CaCu4 intermetallic compounds in equilibrium with aluminum solid solution in the ternary Al–Ca–Cu alloying system were comprehensively analyzed. The (Al,Cu)4Ca intermetallic compound is treated as a line phase based on the Al4Ca phase with Cu substituted by Al. The solubility of copper in the compound reaches 10 at.% (19 wt.%), which leads to marked changes in the crystal lattice structure, physical and mechanical properties of the compound. For instance, the density of the compound increases from 2.22 to 2.79 g/cm3 and the microhardness from HV 180 to HV 250. The Al27Ca3Cu7 phase is treated as a strict stoichiometric ternary compound with a primitive BaHg11 type crystal structure of the Pm3m space group. The lattice parameter is accepted to be 8.514 Å corresponding to a density of 3.45 g/cm3. The Al8CaCu4 phase is also a strict stoichiometric ternary compound with a tetragonal crystal lattice structure of the Mn12Th type. The phase has the highest microhardness (HV 505) and density (4.57 g/cm3). The alloys pertaining to the binary (Al)+(Al,Cu)4Ca phase field and the quasi-binary (Al)+Al27Ca3Cu7 section can be considered promising as the base for new natural aluminum matrix composites.

Formation and characterization of Al10CaFe2 compound in Al−Ca−Fe alloys

The phase diagram of the Al−Ca−Fe system in the aluminum corner, including the liquidus projection and solidification reactions, was studied by using thermodynamic calculations and experimental techniques. The results show that instead of the Al3Fe phase, a ternary compound whose composition corresponds to the formula Al10CaFe2 should be in equilibrium with the aluminum solid solution (Al). Thе transition from the binary to the ternary compound occurs via the peritectic transformation L + Al3Fe → (Al) + Al10CaFe2 (at 638 °C, 3.3 at.% Ca and 0.5 at.% Fe). Primary and eutectic crystals of the ternary compound have a compact morphology, in contrast to needle-shaped inclusions of the Al3Fe phase. First principles calculations and X-ray diffraction analysis were used to determine the crystal lattice structure of Al10CaFe2 ternary compound. In addition, the near eutectic alloy Al−6wt.%Ca−1wt.%Fe after annealing at 500−600 °C has a fine structure with a total fraction of excess phases of about 25 vol.%. Thus, the Al−Ca−Fe system can be used to create new aluminum-matrix composite alloys.

Сравнительный анализ химического состава и механических свойств различных участков сварного соединения дюралюмина, полученного сваркой трением с перемешиванием

Friction stir welding is an advanced method of joining various metals and alloys in the aircraft and mechanical engineering industries. This type of welding is used to join materials that are difficult to weld or not weldable by conventional methods. The high-strength D16 aluminum alloy is difficult to weld by fusion, which is associated with the formation of a dendritic structure in the fusion zone leading to a decrease in the mechanical strength of the joint. In the work, the microstructure and microhardness of a welded seam of the D16 aluminum alloy produced by friction stir welding was studied. Using scanning electron microscopy and optical metallography, the authors identified the presence of three zones: the weld core, the thermomechanical impact zone, and the heat effected zone. In the central part of the welded joint (in the core), a laminated onion ring structure was discovered. A change in the chemical composition of the aluminum solid solution was identified in different areas of the weld zones, as well as the presence of a concentration gradient within each zone. In the upper part of the welded seam, the solid solution is silicon-enriched and depleted in copper. Due to the solid solution depletion in alloying elements, the aluminum content in the solid solution in the zone of the welded joint is higher compared to the initial state. The microhardness values in different areas of the welded joint correlate with changes in the chemical composition. In the welded joint zone, a significant decrease in microhardness was found compared to the initial state, and a change in microhardness associated with the chemical composition gradient within each zone was also observed.

Experimental study on TIG full welding and single pass welding quality of 6061-T6 aluminum alloy sheet

6061-T6 aluminum alloy plate (3 × 150 × 300 mm3) was welded by tungsten inert gas (TIG) welding. The welding process methods are single-pass welding process and full welding process respectively. The effects of different welding processes on the performance of TIG welding 6061-T6 aluminum alloy were compared and studied. The effects of microstructure and precipitation on the microhardness and tensile strength were analyzed by optical microscope, scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) characterization, electron backscattering diffraction (EBSD) characterization, microhardness and tensile test. The microstructure of the weld zone is mainly composed of aluminum solid solution (α-Al) dendritic structure and Al–Si eutectic structure. Through EBSD characterization analysis, the average grain size of the weld zone of the full welding process and the single-pass welding process is about 45 μm and 55 μm, and the grain size of the heat-affected zone and the weld zone of the two welded joints does not change significantly. The hardness curves of the two welded joints have the same distribution trend, which is roughly 'W' type distribution. In the tensile test, the tensile strength of the single pass welding process is lower than that of the full welding process, and the fracture of the tensile parts is dimple structure, which is ductile fracture. Through analysis and comparative study, the full welding process is better than the single-pass welding process when welding 6061-T6 aluminum alloy sheet.

In Situ Heating Positron Annihilation Lifetime Spectroscopy Experiments on an Al–Mg Alloy

The binding between vacancies and Mg atoms in an aluminum solid solution is not fully understood but essential for understanding its role in age hardening of many Al alloys. After annealing and quenching, Mg prevents the loss of excess vacancies during natural ageing and forms complexes containing one, possibly two, vacancies, and various Mg atoms. By heating the alloy after natural ageing, these complexes are dissolved, i.e., natural ageing is reverted. This reversion process is studied by in situ positron annihilation lifetime spectroscopy utilizing the very high count rate at the accelerator driven facility ELBE. Positron spectra are continuously acquired during heating at rates between 3 and 50 K min−1. After correcting for the contributions of the oxidized surface and decomposing spectra into components, the process can be followed in detail and is found to take place in distinct stages: first, the number of vacancy–Mg complexes is reduced and then the liberated vacancies agglomerate into clusters that eventually dissolve at even higher temperatures.

Metallurgical aspects of the corrosion resistance of 7000 series aluminum alloys – a review

Abstract This article contains a review of selected studies conducted in the field of corrosion resistance of precipitation-hardenable 7000 series aluminum alloys. In particular, it discusses the effect of heat treatment and the role of thus formed microstructure on the corrosion behavior of these alloys. The article presents the three types of corrosion that occur most commonly in this group of materials in the context of their microstructure. It points to the importance of the chemical composition of a 7000 alloy, including the precipitates present in the microstructure, for the development of corrosion. The aluminum solid solution can act as an anode or cathode in relation to intermetallic particles. Such corrosion features may result in the destruction of the surfaces of elements made of the 7000 series aluminum alloy. It also raises the issue of the mechanism of corrosive destruction of the aluminum solid solution, which is connected with a crystallographic attack. In the case of this process, the nature of the micro-pits formed as a result of their local dissolution is related to the privileged dissolution of specific crystallographic planes and directions.

Magnetic monopole's role in hydrogen bubbles formation in rapidly solidified Al–Cu–Zn alloys

Hydrogen hydrides are formed when hydrogen is trapped in the aluminum solid solution of rapidly cooled Al–Cu–Zn alloys. The formation of these hydrides is of great interest because they have unique properties that make them useful in a variety of applications. One potential application is in the field of energy storage, where hydrogen hydrides could be used as a way to store hydrogen for use in fuel cells. Another potential application is in the field of catalysis, where these materials could be used to promote chemical reactions. Highlighting of magnetic monopoles in Al-30 wt%Cu-2wt.%Zn and stable skyrmions, at room temperature, in non-magnetic Al-50 wt%Cu-2wt.%Zn is also groundbreaking development in the field of materials science, as it suggests that there may be new ways to manipulate and control the properties of these materials. We observed a remarkable consequence of these phenomena: the transmutation of aluminum into silicon. This is a significant finding, as we believe we are the first to approach this process in this way. This could lead to breakthroughs in materials science and engineering, with potential applications in fields such as electronics, photonics, and nanotechnology.

Structure Evolution and Mechanical Properties of Sheet Al–2Cu–1.5Mn–1Mg–1Zn (wt.%) Alloy Designed for Al20Cu2Mn3 Disperoids

This work was focused on studying the possibility of increasing the strength of non-heat-treatable sheet alloy Al2Cu1.5Mn (wt.%) by the joint addition of 1% Mg and 1% Zn. The effect of these elements on the structure and mechanical properties of the new sheet Al2Cu1.5Mn alloy designed for Al20Cu2Mn3 dispersoids has been studied by calculations and experimental methods. The obtained data on the phase composition, microstructure, and physical and mechanical properties of the new alloy for different processing routes (including hot rolling, cold rolling, and annealing) have been compared with those for the ternary Mg- and Zn-free alloy. It has been shown that the formation of nanosized Al20Cu2Mn3 dispersoids (~7 vol.%) provides for the preservation of the non-recrystallized grain structure after annealing at up to 400 °C (3 h), while Mg and Zn have a positive effect on the strength due to the formation of alloyed aluminum solid solution. As a result, cold-rolled sheets of the Al2Cu1.5Mn1Mg1Zn model alloy showed a substantially higher strength performance after annealing at 400 °C in comparison with the ternary reference alloy. In particular, the UTS is ~360 vs. ~300 MPa, and the YS is 280 vs. 230 MPa. For the example of the Al2Cu1.5Mn1Mg1Zn model alloy, it has been shown that the system is promising for designing new heat-resistant alloys as a sustainable alternative to the 2xxx alloys. The new alloy has an advantage over the commercial alloys (particularly, 2219, 2024, 2014), not only in manufacturability but also in thermal stability. The sheet production cycle for the model alloy is much shorter because the stages of homogenization, solution treatment, and water quenching are excluded.

Structure and strength of Al-Mn-Cu-Zr-Cr-Fe ALTEC alloy after radial-shear rolling

The phase composition and structure of as-cast and deformed Al-1.53Cu-1.66Mn-0.38Zr-0.15Cr-0.15Fe (wt.%) were investigated. The radial shear rolling was used for the deformation of the alloy. The structure of as-cast alloy consists of aluminum solid solution, eutectic Al6(FeMn) and Al2Cu, as well as Al7Cr and Al20Cu2Mn3 dispersive particles. It is assumed that radial shear rolling results in the refinement and partial dissolution of Al20Cu2Mn3 dispersoids. Along with this, significant grain refinement was established after deformation. The average grain-subgrain size in the alloy after deformation is 1.6 μm. After deformation the alloy has the yield stress of 83 MPa and ultimate strength of 216 MPa. The elongation to failure of the deformed alloy is 25 %. Owing to the partial deformation induced dissolution of the aluminides and supersaturated solid solution formation, there is a potential for strengthening upon heat treatment of the alloy and improvement of its thermal resistance.

Mechanical properties and electrical conductivity of Al–Y–Sс–Er cold worked alloy

Aluminum alloys alloyed with rare earth and transition metal are promising materials for electric energy transportation due to their high properties of strength, thermal stability, and electrical conductivity. The features of strengthening, their mechanical properties and electrical conductivity of Al–0.2Y–0.2Sc–0.3Er alloy after cold rolling have been established. The alloy as a cast structure is presented by aluminum solid solution (Al) and dispersed eutectics with τ2 (Al75-76Er11-17Y7-14) phase upon complete dissolution of scandium in (Al), and a content of yttrium and erbium at the level of 0.2–0.3 % each. Cold rolling the ingot accelerates strengthening upon annealing at 270 and 300 °C, reducing the time of achieving peak hardness. The maximum strengthening due to precipitation of L12 dispersoid of Al3(Sc,Y,Er) phase with the average particle size up to 10 nm is achieved after 7 h of annealing at 300 °C after cold rolling. This shows the prevailing heterogeneous mechanism of nucleation due to defects accumulated during cold rolling which stimulates strengthening. The eutectic particles are located mainly along the boundaries, elongated in the rolling direction. Irrespective of the mode of sheet fabrication, the alloy demonstrates high thermal stability up to 400 °C. During annealing of the sheets to 450 °C, their non-recrystallized structure is retained. Ingot annealing at t = 300 °C in 7 h and cold rolling with subsequent annealing under the same conditions provide a high level of mechanical properties and electrical conductivity: σ0.2 = 194 MPa, σu = 210 MPa, δ = 12.1 % and IACS – 60,1 %. The alloy has demonstrated high yield stress up to 100 h of annealing at t = 300 °C.

Description of the New Eutectic Al-Ca-Cu System in the Aluminum Corner

The structure of the new ternary eutectic Al-Ca-Cu system considered as a replacement for the ternary eutectic system Al-Ce-Cu widely used for additive manufacturing has been studied using experimental techniques. The liquidus projection of the Al-Ca-Cu system in the aluminum corner has been suggested based on experiential studies of the microstructure and phase composition of model alloys. The suggested structure of the diagram has two quasi-binary sections: (Al)-Al27Ca3Cu7 and (Al)-Al8CaCu4 and three invariant eutectic transformations: L→(Al) + (Al,Cu)4Ca + Al27Ca3Cu7 (at 5.6 wt.% Ca, 4.5 wt.% Cu, 595 °C), L→(Al) + Al27Ca3Cu7 + Al8CaCu4 (at 2.2 wt.% Ca, 13.5 wt.% Cu, 594 °C) and L→(Al) + Al8CaCu4 + Al2Cu (at 0.5 wt.% Ca, 34 wt.% Cu, 544 °C). The limit solubility of copper in aluminum solid solution (Al) at 530 °C reaches ~5.1 wt.% in the ternary phase field (Al) + Al8CaCu4 + Al2Cu and drops to ~2.4 wt.% in the (Al) + Al8CaCu4 + Al27Ca3Cu7 ternary phase field. For the example of the model ternary hypoeutectic alloys with a predominant content of the eutectic (Al,Cu)4Ca phase, it has been shown that the system is promising for designing new eutectic-type alloys with a natural composite structure.

Surface strengthening phenomenon and mechanism of 6061 solid solution alloy after ultrasonic stress relief

The evolution of residual stress, microstructure and mechanical properties, and their correlations of supersaturated 6061 solid solution alloy were investigated after ultrasonic stress relief. It is found that following ultrasonic stress relief, the residual stress of 6061 solid solution aluminum alloy is gradually released with the hardness of the alloy rising first to a peak and then decreasing gradually to a stable value. After ultrasonic stress relief, the peak hardness of the alloy is capable of reaching 81.8 ± 1.95HV, which is about 45% higher than 56HV of the initial state. When the residual stress was released by about 80%, the hardness of the alloy came to a stable value of 63.75 ± 1.65HV. It is proved that the ultrasonic stress relief could not induce a precipitation of the strengthening phase in the supersaturated 6061 solid solution alloy. The hardening of the alloy was mainly caused by the evolution of dislocation during the residual stress relief process. The superposition of ultrasonic dynamic stress and the internal residual stress in the alloy first prompted the multiplication and entanglement of dislocation, and consequently increase the hardness of the alloy. With further relief of the residual stress, the dislocation multiplication rate slows down and the annihilation rate accelerates, and then the corresponding dislocation density and entanglement are obviously reduced, resulting in a decrease in the hardness of the alloy to a constant.

The effect of abrasive additives on the tribotechnical properties of lubricants for the wheel–rail system

The paper studies the polishing power of a tribochemically active abrasive material based on a solid solution of iron and aluminum oxides, as well as a solid solution of aluminum and iron oxides modified by zirconium oxide and yttrium oxide additives, and the tribotechnical properties of a lubricant doped with these abrasive materials. The modified Al2O3·Fe2O3·ZrO2·Y2O3 powders prove to have an essentially higher polishing power producing a considerably lower surface roughness than that of the unmodified Al2O3·Fe2O3 powder. By varying the content of the modifying oxides, one can change the tribochemical activity of the abrasive powder and select the best composition depending on the material to be polished. The addition of these abrasive powders is shown to have an essential effect on the tribotechnical properties of the lubricant for the wheel–rail contact. The laboratory testing of the lubricant compositions suggests their effective applicability to the wheel–rail contact.

Modifying Copper with Alumina during a Mechanically Stimulated Reaction

IR spectroscopy, electron microscopy, and X-ray diffraction analysis, including the application of synchrotron radiation, have been used to study the mechanochemical reduction of copper oxide with alumi-num at the stoichiometric ratio of the components and in the presence of an excess of oxide-forming metal and aluminum solid solution in copper as well. The possibility is shown of the mechanochemical reduction of copper oxide with aluminum and aluminum solid solution in copper, which is accompanied by the forma-tion of the Сu/Al2O3 composite structure. To modify copper with alumina, using an aluminum solid solution in copper is preferable.