Commercial Aluminum Research Articles

Influence of the intermediate oxidation layer on the characteristics of lead zirconate titanate thin films with aluminium substrate

This paper presents a flexible piezoelectric device that has been realized by depositing lead zirconate titanate (PZT) thin films by chemical solution deposition (CSD) on a commercial aluminum foil as a substrate. The thermal treatment required for the crystallization of the PZT thin films leads to the oxidation of the substrate and a parasitic intermediate layer of alumina (Al2O3) is formed between the substrate and the first PZT layer. The comparison with and without the use of a conductive ruthenium dioxide (RuO2) interlayer, which can shunt the insulating alumina layer, showed the influence of the latter on the different characteristics of the material. The thickness of the alumina layer on the surface of the aluminum substrate after deposition of the PZT film (≈ 39 nm) was determined by calculation and confirmed by transmission electron microscopy (TEM). Dielectric characterization of the sample without considering this layer gives the permittivity of the Al2O3/PZT bilayer and not the active material alone (PZT). A relative permittivity value of 313 is measured against 558 for the single PZT layer if the alumina layer is taken into account, which means a decrease of 44%. The piezoelectric characterization is also influenced by the alumina layer, the piezoelectric coefficient is 14 pC/N while it is 26 pC/N when this layer is taken into account. This study evidences and quantitatively evaluates the influence of the oxidation layer (Al2O3) on the dielectric and piezoelectric characteristics and mechanical energy harvesting performances.

A rapid and effective method for alloy materials design via sample data transfer machine learning

One of the challenges in material design is to rapidly develop new materials or improve the performance of materials by utilizing the data and knowledge of existing materials. Here, a rapid and effective method of alloy material design via data transfer learning is proposed to efficiently design new alloys using existing data. A new type of aluminum alloy (E2 alloy) with ultra strength and high toughness previously developed by the authors is used as an example. An optimal three-stage solution-aging treatment process (T66R) was efficiently designed transferring 1053 pieces of process-property relationship data of existing AA7xxx commercial aluminum alloys. It realizes the substantial improvement of strength and plasticity of E2 alloy simultaneously, which is of great significance for lightweight of high-end equipment. Meanwhile, the microstructure analysis clarifies the mechanism of alloy performance improvement. This study shows that transferring the existing alloy data is an effective method to design new alloys.

The Progress and Comprehensive Analysis of Supercapacitors for Alternating Current Line Filtering: A Review

AbstractTo address the potential application of supercapacitors (SCs) in the field of alternating current filtering, this review summarizes the working mechanism toward ultrafast response, the progress of SCs in electrode materials, electrolytes (aqueous, organic electrolyte, and ionic liquids), current collectors, as well as device configuration. The performance of SCs is compared comprehensively with that of the commercial aluminum electrolyte capacitor (AEC) from the viewpoint of operating temperature, voltage, response time, impedance phase angle, and capacitance. Especially, there exists a big gap between AECs and SCs in terms of the operating temperature and operating voltage. And we give insights into future research focus for high‐frequency SCs, in terms of mechanism, structural design, and application management.

Modelling Age Hardening of Aluminium Alloys with Consideration of GP Zones or Clusters

The work reported here follows the theme of our previous research presented at the ICAA16 and ICAA17 conferences, where material models have been developed to predict the microstructure evolution and precipitation hardening of aluminium alloys during cooling and ageing. The models have two important features: one is the consideration of quenched-in vacancies and their effect on precipitation kinetics, which was discussed in past conferences; the other is the formation of GP zones or clusters and their transition to other hardening phases during ageing, which is the focus of this paper. GP zones or clusters are known to serve as precursor phases for various hardening phases. Depending on the ageing temperature being above or below the solvus temperature of the precursor phase, precipitates can either form on their own from the matrix (heterogeneous or HET type) or form on existing GP zones or clusters (homogeneous or HOM type). In the latter case, GP zones or clusters are allowed to form first from the matrix, which will later transform to their metastable counterparts. Both HET and HOM types of precipitates are considered in the current strengthening model for predicting age hardening curves for aluminium alloys. The age hardening model has been validated over a wide range of commercial aluminium alloys and demonstrated good agreement with experimental data in the form of age hardening curve and T5/T6 peak position and strength.

Cladding and Natural Aging of Aluminium Alloy 2024 for Aircraft Application

Aluminium alloy 2024 is widely used in the manufacturing of aircraft components such as skin panels for the wing. Generally, the aluminium alloy 2024 is delivered as cold work condition i.e., 2024 T3. However, the aluminium alloy 2024 T3 does not meet the standard for aircraft wing skin. Therefore, further treatments such as cladding and heat treatment are carried out to improve its quality. Cladding was introduced to the 2024 T3 alloy at 495 °C using commercial purity aluminium. Subsequently, T42 heat treatment was introduced to the 2024 T3 alloy at 500 °C for 40 minutes, then followed by quenching and natural aging for 96 hours, yielding 2024 T42 aluminium alloy with cladding (T42 Clad). 2024 T42 aluminium alloy without cladding (T42 Bare) was also obtained by T42 heat treatment of 2024 T3. The effect of cladding and natural aging on mechanical properties is investigated by tensile test and hardness test. Conductivity meter was used to determine the electrical conductivity. Intergranular corrosion test and stress corrosion crack test were performed to investigate the effect of cladding and natural aging on corrosion resistance. Results indicate that the solution treatment and natural aging improve corrosion resistance, mechanical properties, but reduce electrical conductivity values. Cladding gives higher electrical conductivity value and elongation. Both natural aging and cladding treatment provide appropriate aluminium alloy for aircraft wing skins.

Failure mechanism during incremental sheet forming of a commercial purity aluminum alloy

Incremental sheet forming (ISF) is known for many advantages over conventional forming, such as part flexibility, low tooling cost and higher formability. Previously various studies have explored the failure mechanism experimentally and numerically. However, limited studies have been performed on the micro-mechanics of failure during ISF process. This study involves failure mechanism during incremental sheet forming of a commercial purity aluminum alloy (AA1050). During experiments, failure (fracture) was observed in truncated cone specimens by increasing the wall angle from 71° to 72°. The mechanism behind failure was explored with detailed microstructural characterization and finite element (FE) simulations. Various samples were taken from the successfully formed and failed cones for microstructural analysis. The electron backscatter diffraction (EBSD) based microtexture measurements associate this failure with more grain fragmentation and necking or localized deformation in the failed cone. Further, the X-ray diffraction (XRD) based residual stress measurements indicate high positive (tensile) hydrostatic stresses (∼157 MPa) on the outer surface of the failed (fractured) cones. Finite element analysis (FEA) with Gurson-Tvergaard-Needleman (GTN) damage model was used for fracture prediction. The FEA results also support the residual hydrostatic stress evolution in the cones, albeit at a slightly different wall angle. Based on microstructural and finite element analysis it is concluded that deformation becomes inhomogeneous when the failure occurs during ISF process.

Microstructure, mechanical properties and fatigue behaviour of a new high-strength aluminium alloy AA 6086

This study presents the comprehensive experimental investigation of the microstructure, mechanical and fatigue properties of a new high-strength aluminium alloy AA 6086, which was developed from a commercial aluminium alloy AA 6082. The new alloy possesses a higher content of Si, and, it also contains Cu and Zr. The alloy was characterised in the as-cast condition after homogenisation, extrusion, and T6 heat treatment. Light microscopy, scanning and transmission electron microscopy with energy dispersive spectrometry were used to analyse the microstructure and the fractography of broken specimens. The quasi-static and fatigue tests were performed on the MTS Landmark 100 kN servo-hydraulic test machine, controlled with a mechanical extensometer with a 25 mm gauge length. The quasi-static strength of the analysed aluminium alloy AA 6086 was found to be significantly higher if compared to some other AA 6xxx alloys, while the ductility was kept almost the same. The experimental results of the comprehensive fatigue tests in a Low Cycle Fatigue (LCF) and High Cycle Fatigue (HCF) regime showed a good fatigue resistance, and represent a good basis for engineering design applications of the newly developed aluminium alloy AA 6086.

Radon detector development using a PIN photodiode

An active device for radon detection in air has been developed in the frame of a project carried out by the Physics Department of the University of Torino with the aim to create a monitoring network of radon concentration in the University workplaces.
 The device uses a commercial planar photodiode, sensitive to alpha particles, and a dedicated electronic chain integrated in an approx. 30 mm by 50 mm printed circuit board (PCB), designed in order to minimize the power consumption. The device can be used not only as alpha particles counter (using the digital output) but also for alpha spectroscopy, connecting the analog signal output from the shaper amplifier to a Multichannel Analyzer (MCA).
 In this paper, the first prototype of the detector will be presented with the preliminary experimental results.
 The spectroscopic performances of the device were tested, integrating the sensor in a commercial aluminum box and acquiring the alpha particle spectrum from a calibration source and from rock samples used as radon sources.
 The radon sensitivity of the detector, in terms of (Counts per hour)/(Bq m−3), was assessed by the comparison with a calibrated commercial radon detector (RAD7 Durridge Inc.).
 In conclusion, the final prototype will be presented. It is characterized by a new 3d printed plastic case in black PA12 for light shielding, covered by a conductive paint in order to minimize the electromagnetic noise.

Heterogeneous Fenton- and photo-Fenton-like catalytic degradation of emerging pollutants using Fe2O3/TiO2/pillared clays synthesized from aluminum industrial wastes

The presence of emerging pollutants (EPs) in water is a major environmental concern. This study evaluates for the first time the removal of three EPs, namely triclosan (TCS), 2,6-dichlorophenol (2,6-DCP), and bisphenol A (BPA), 90 μmol/dm3, from water through both Fenton- and photo-Fenton-like reactions using montmorillonite (Mt) and aluminum interlayered pillared clays (Al-PILC) as catalytic supports. The catalysts (Fe2O3/TiO2/Mt and Fe2O3/TiO2/Al-PILC) were evaluated in single-component solutions and in an equimolar mixture. Two Al-PILC were synthesized from a hazardous waste, namely aluminum saline slag, using either the acid (Al-PILCAE) or the alkaline (Al-PILCBE) aluminum extract as precursors. The third Al-PILC was obtained by the conventional method using a commercial aluminum salt (Al-PILCCM). Catalytic supports were impregnated at 10 and 20 wt% titanium. Iron loadings from 1 to 20 wt% were tested for Mt, while only 20 wt% iron was tested for Al-PILC. All catalysts were characterized using several techniques and the results confirmed the formation of TiO2 and Fe2O3. Almost 100 % of TCS and 2,6-DCP were removed by both Fenton-like (240 and 420 min, respectively) and photo-Fenton-like reactions (30 and 90–120 min, respectively) using the Al-PILC based catalyst. The maximum removal for BPA was 80.14 ± 1.93 % after 120 min under photo-Fenton-like conditions using Al-PILCBE. The catalysts synthesized using the four catalytic supports showed good results for the removal of TCS by both processes, while for 2,6-DCP and BPA the best results were obtained using Al-PILCAE and Al-PILCBE as catalytic supports. Finally, a degradation pathway was suggested for every pollutant based on the by-products identified during the reactions by HPLC-MS. The results revealed that the materials used in this work are suitable catalysts for removing emerging pollutants from water by both Fenton- and photo-Fenton-like reactions.

Dissimilar diffusion bonding of bulk metallic glass: Amorphous/crystalline atomic-scale interaction

Dissimilar diffusion welding of a copper-based bulk metallic glass (BMG) with a stoichiometry of Cu 50 Zr 43 Al 7 and commercial pure aluminum was performed at evaluated different temperatures (below and higher than the glass transition temperature ~ 440 °C) and holding times (up to one hour). The main goal was to successfully bond these dissimilar materials without crystallizing the BMG part to avoid deteriorating properties. Optimum joining conditions were attained at a temperature of 430 °C (<T g ) and dwell time of 60 min. The diffusion-assisted atomic-scale interactions between the amorphous and crystalline structures were studied using electron microscopy. To this end, the interaction zone at the BMG/Al dissimilar interface was extracted and analyzed by focused ion beam/transmission electron microscopy (FIB/TEM) followed by elemental analysis and high resolution-transmission electron microscopy (HR-TEM) to reveal the nature of the diffused layer and orientation relationships within the structure. Based on microscopy observations, the formation of an interaction layer with a thickness in the range of 1–2 μm was observed, confirmed by diffusion of oxygen to this region. High-resolution atomic-scale observations supposed a gradient transition from crystallinity toward the amorphous state undergoing the formation of some semi-crystalline nano-scale layers. The activation energy for the thermally-assisted diffusion bonding process was estimated at ~486.7 kJ/mol, related to the substitutional diffusion of oxygen through the copper matrix after decomposition of the stable alumina oxide layer on the surface. Accordingly, an increased indentation hardness across the dissimilar interface was observed and attributed to the distribution of elements into the reaction layer and the formation of new phases. • Atomic-scale diffusion bonding of Cu-based BMG to Al was studied by FIB-TEM analysis. • Elemental inter-diffusion in amorphous-crystalline materials interaction characterized. • Decomposition of oxide surface layer and formation of a semi-crystalline phase at the interface associated bonding. • A gradual atomic structure transition from amorphous to crystallinity was revealed across the interface. • The activation energy of the bonding process was estimated at ~486.7 kJ/mol, nearby to substitutional diffusion of oxygen.

The influence of carbide reinforcement on the properties of sintered aluminium alloy matrix composites

Based on the commercial aluminium alloy powder blend (Alumix 431D) metal matrix composites reinforced with particles of SiC as well as TiC were produced by conventional powder metallurgy technology and the effect of the type and amounts of reinforced particles on the selected properties and microstructure of sintered composites were investigated. In particular, the densification behaviour, the wear resistance and the corrosion resistance in 3.5% NaCl solution were identified. It was stated that both the type and the weight fraction of carbide used as particulate reinforcement have a great impact on the properties of aluminium alloy matrix composites. It was shown that the introduction of titanium carbide has a more favourable effect on the properties of sintered Alumix 431D matrix composites in comparison to silicon carbide and the optimum content of TiC in composite is 4 wt. % due to the highest hardness, wear resistance (wear rate of 2.86510-3 mm3/m) and simultaneously the best corrosion resistance (corrosion rate of 0.005 mm/year).

Investigation of commercial aluminum alloys as anode materials for alkaline aluminum–air batteries

Employed as anode materials for aqueous alkaline Al–air batteries, commercial aluminum alloys realized energy conversion and resource sustainability.

Microstructure and corrosion resistance of commercial purity aluminum sheet manufactured by continuous casting direct rolling after ultrasonic melt pre-treatment

During the new continuous casting direct rolling (CCDR) process for manufacturing commercially pure aluminum sheet for foils, casting defects tend to arise as the raw material with huge mass flow rapidly solidifies under a high cooling rate, which generates negative effects on the formability of aluminum sheets and the performance of final foil products. Therefore, melt pre-treatment during continuous casting is very essential to improve the quality of the billet. In this study, multi-source ultrasonic field was employed to pretreat an Al melt during the continuous casting stage in a Hazelett CCDR strip production line. The Ti content distribution in the melt, the microstructure and corrosion behaviors of the rolled sheet with and without ultrasonic melt pre-treatment (UMPT) were investigated. The microstructure of the rolled sheet was refined due to the increased Ti content and uniformly distributed Al3Ti particles under UMPT. In addition, the morphology of the Fe-containing secondary phase was modified from an aggregated to a scattered structure, with reduced continuity. As a result, under the combined effects of the refined α-Al grains and secondary phase, the corrosion resistance of the rolled sheet was improved. The underlying mechanisms for the modifications of the microstructure and corrosion resistance after UMPT are also interpreted, which gives theoretical guidance on the practical applications of the ultrasound-assisted continuous casting in industrial production.

Hydrostatic twist extrusion (HTE) for processing relatively long ultrafine grained samples

In this study, hydrostatic twist extrusion (HTE) has been introduced for processing relatively long ultrafine grained (UFG) bulk samples. By using high-pressure fluid surrounded the sample, surface contact between die and sample was eliminated. The high-pressure fluid causes high hydrostatic pressure, which leads to improvement of material properties and increased the aspect ratio of the sample (length/diameter). The HTE process was applied to commercial pure aluminum samples at room temperature, and then microstructure and mechanical properties were examined. The results demonstrate that after HTE process, the grain size was reduced from 54 µm to ∼800 nm, and microhardness was increased from 29.2 HV to 37.7 HV. Also, yield and ultimate strength were noticeably increased from 78 MPa and 103 MPa to 166 MPa and 175 MPa, respectively. This process seems to be very promising and interesting for the future industrial application.

Effect of HPT straining and further natural aging on the structure and hardness of aluminum alloy 1965 with nanosized TM aluminides

Pre-quenched samples cut from a homogenized ingot of commercial aluminum alloy 1965 with a grain size of about 21 µm were compressed at 6 GPa and then strained by torsion up to 10 revolutions at room temperature. TEM, SEM and XRD analyses showed that the strengthening / softening of the alloy during further natural aging up to 500 hrs was controlled by simultaneous decomposition of the aluminum solid solution and recovery of its deformation structure. It was found that the two-level nanostructuring of the alloy (precipitates and matrix) is accompanied by more than twofold strengthening up to a hardness of about 250 HV. The main contribution was made by dislocation and structural hardening due to the formation of a highly work-hardened structure of the nanofragmented type. During subsequent aging, the change in hardness was controlled by both the preliminary strain and the aging time. A continuous increase in strength with strain and aging time was found in the samples after pressing and torsion up to 1 revolution. In other conditions, strengthening was preceded by softening, the magnitude and duration of which were also proportional to the strain. The nature of the alloy behavior and the role of nanosized aluminides of transition metals are discussed in details.

Evaluation of Crocin as green corrosion inhibitor for aluminum in NaCl solution

The role of Crocin, which is a natural organic substance from the Greek plant Crocus sativus, is investigated as a green corrosion inhibitor for the AA 1050 commercial aluminum alloy in 0.01 M sodium chloride solution. Its action was assessed by Linear and Tafel Polarization, as well as by mass loss measurements and confirmed by observation and analysis of the surface morphology of the specimens by Scanning Electron Microscopy. Corrosion inhibition efficiency of Crocin improves with concentration and at 1.25 mM was estimated in the range of 90-95%, which indicates the formation of an adsorbed layer that isolates and protects the surface. Experimental results showed that Crocin acts as a mixed-type inhibitor with predominantly anodic effectiveness, also retarding pitting corrosion process. The inhibitive action of Crocin was explained by theoretical calculations employing density functional theory, semiempirical PM6 and molecular mechanics methodologies, showing good agreement with experimental results. The reactivity of Crocin is attributed to chemisorption on the Al2O3 surface through its vicinal hydroxyls of the sugar moiety. This process is assisted by the π-conjugated system of the polyene chain together with the extended electron delocalization over the oxygen atoms of the esterified carboxyl groups, as well as by the intense electrostatic potential regions located on the sugar moiety of the Crocin molecule.

Solid State Joining of a Cold Rolled Zr-Based Bulk Metallic Glass to a Wrought Aluminum Alloy by Power Ultrasonics.

Ultrasonic metal welding (UMW) enables joining in the solid state at relative low temperatures with short cycle times. This technique is of particular interest for joining metallic glasses to each other or to other materials, because crystallization of the amorphous structure can be prevented due to the low thermal loading and the rapidity of the process. In this work, UMW is applied to join one 1 mm thick sheet of a commercial wrought aluminum alloy (AA5754) and one 0.4 mm thick strip of a commercial Zr-based bulk metallic glass (AMZ4). The introduced heat of the welding process is detected with thermocouples and thermal imaging. To investigate the strength of the joint and the influence on the microstructure, mechanical tensile tests are carried out in combination with scanning electron microscopy and differential scanning calorimetry. The results show that ultrasonic metal welding is a suitable technique to join amorphous bulk metallic glasses to crystalline aluminum alloys. The metallic glass component retains its amorphous structure in the joint, and the joint strength is higher than the strength of the Al sheet. These findings will help to develop future applications of BMG-based multi-material components, including medical tools.

Aqueous hybrid electrochemical capacitors with ultra-high energy density approaching for thousand-volts alternating current line filtering

Filtering capacitors with wide operating voltage range are essential for smoothing ripples in line-powered system, which are still unsatisfactory due to low energy density and limited working voltage scopes. Herein, we report an aqueous hybrid electrochemical capacitor with areal specific energy density of 1.29 mF V2 cm−2 at 120 Hz, greater than common aqueous ones. Interestingly, it can be easily integrated at scale to show excellent flexibility, controllable and stable filtering performance, in which an integrated device (e.g., seven units in series) exhibits fluctuation of 96 mV, 10 times smaller than an aluminum electrolytic capacitor with similar capacitance. A record-high 1,000 V can also be achieved after integrating 670 units, exceeding those reported so far, and about 1.5 times of commercial bulk aluminum electrolytic capacitors (~700 V). This work opens up a new insight for promising applications in multiple electricity transmission systems that requiring high smoothness under harsh voltage.

Surface characteristics of AC PEO coatings fabricated on commercial Al alloys

The effect of alloying elements on coating characteristics was explored in the current work, which involved the fabrication of ceramic oxide coatings on commercial aluminium alloys (AA2024, AA6061, and AA7075) using the plasma electrolytic oxidation (PEO) process. The PEO coatings were fabricated by an AC power source with an exchange current density of about 300 mA/cm2. Field emission scanning microscopy (FESEM) was used to examine the surface, cross-sectional morphology, and alloying elements distribution. X-ray diffraction was used to investigate the phase composition. All PEO coatings were primarily composed of γ-Al2O3 and α-Al2O3 phases. As compared to PEO treated AA6061, PEO treated AA7075, and PEO treated AA2024 suppress the formation of α-Al2O3, resulting in a relatively higher fraction of γ-Al2O3, attributed to the alloying elements residing in the coatings. Because of its dense inner layer and high thickness (51 ± 1 μm), as well as its higher contact angle (114 ± 2°). PEO coated AA6061 sample exhibited superior corrosion resistance with lower icorr = 8.91(±0.24) E-6 mA/cm2 and impedance (Ω-cm2) to the order of 107 in 3.5 wt% aqueous NaCl corrosive medium. The PEO-coated AA6061 sample evinced greater hardness, scratch and wear resistance than the other samples, ascribed to its relatively higher α-Al2O3 phase, lower residual alloying elements, and thick and dense inner layer.

Energy consumption, wear and corrosion of PEO coatings on preanodized Al alloy: the influence of current and frequency

The influence of current and frequency on energy consumption of plasma electrolytic oxidation (PEO) of a commercial aluminium alloy pre-treated by conventional anodizing in sulphuric acid has been investigated. The combination of a 20-μm thick precursor anodic porous film, high current (500 mA cm−2) and frequency (400 Hz) during PEO enables up to 76% energy savings compared to direct PEO treatment (50 Hz). The time needed to achieve a uniform coating thickness was also reduced from 3350 s to 750 s, for PEO_50 and A + PEO_400, respectively. The wear and corrosion performance of the optimised coatings (400 Hz) were also improved despite the lower thickness of the coatings. Such improvement was mainly attributed to the microstructural refinement associated with high frequency processing and early transaction to the “soft-sparking” regime. The modification of the frequency has a stronger influence on the corrosion response than the presence of the anodic precursor. The best corrosion response was obtained for PEO_400 followed closely by A + PEO_400.