Papers by Keyword: Aluminum

Abstract: Optimizing the mechanical properties of aluminum to titanium welds is crucial to establish applications for dissimilar lightweight structures in the aerospace industry. In this context, solid-state welding technologies have proven effective in terms of short joining cycles, allowing the combination of cost-effective production and structural weight optimization. However, metallurgical effects between aluminum and titanium in the joint interface are still not completely understood due to differences in physical as well as chemical characteristics. In this study, aluminum alloy 6013 was welded to Ti6Al4V by refill Friction Stir Spot Wel ding, including systematic variations of Mg and Si alloying element content in the used AA6013 sheets. In total five different Al alloys were welded to the titanium to investigate the influence of Mg and Si during processing. Apart from the material selection, the weld strength is mainly influenced by the intermetallic compound thickness at the interface, which in turn primarily depends on the exposed temperature cycle. Consequently, major interest during this study was given on the temperature evolution, interfacial features and the global mechanical properties.

Abstract: The impact of Si on Zn-induced liquid metal embrittlement (LME) in 3^rd generation advanced high strength steels (AHSS) during resistance spot welding has been widely studied, but the effect of Al is rather unknown. This study investigates the substitution of Al for Si by analyzing two steels with the fixed C and Mn-contents of 0.2 and 3 wt.-% respectively. Si and Al-contents are both set to 1.4 wt.-%. To minimize microstructural effects, all steels were quenched and tempered before electro-galvanizing. The effects of Si and Al were examined using hot tensile testing (600 – 900 °C, in 50 K steps) on a Gleeble 3800, resistance spot welding with prolonged welding times, thermodynamic calculations with Thermo-calc® and dilatometry. Results indicate that the use of either Si or Al increases the LME-susceptibility but substituting Al for Si significantly reduces Zn-induced LME-cracking. In hot tensile testing, higher testing temperatures generally increase the steel’s vulnerability to LME. But comparing both alloying elements to one another, Si causes a higher LME-susceptibility.

Abstract: The superplastic deformation behavior, microstructure evolution in the volume and on the FIB-milled surface of the samples of fine-grained AA5083-type alloy with an initial grain size of ~5 µm were investigated, and the role of deformation mechanisms was discussed for two superplastic deformation regimes (1) a strain rate of 1×10^-3 s^-1 and a temperature of 0.87T_i.m. and (2) a strain rate of 5×10^-3 s^-1 and a temperature of 0.97T_i.m.. The m values were ~0.45-0.55 and elongations to failure were ~300% and ~600% for the first and second regimes, respectively. According to the shifts of the marker grid lines after straining to e=0.41, GBS contributed ~33% and ~23% to the total strain in the low-temperature and high-temperature deformation, respectively. The dislocation-induced intragranular deformation provided ~30% for the low temperature regime and ~20 % for the high temperature regime, and remaining 30-50% of strain was localized in the striated zones formed at the across grain boundaries due to both GBS and diffusion creep deformation mechanisms. Considering the strain induced by grain elongation for the low and high temperature deformation regimes, it was concluded that diffusion creep contributed 23% and 34% of the total deformation, and the recalculated GBS contribution, including both FIB grid shifts and a portion of the strain localized in the striated regions, was 43% and 38%, respectively.

Abstract: In the production of layered steel-based composite materials by the liquid-phase method, an importance is attached to preserving the structural and physical-mechanical characteristics of the steel sheet serving as the middle layer. The temperature field in such a steel layer contacting with aluminum melt at a temperature of ~700°C in a roller-crystallizer is analyzed. A formula is obtained that can be used to determine the temperature distribution in the middle layer of steel at the initial stage of the technological process. A comparison of the theoretical results with experimental studies of the thermal modes of obtaining a layered steel–aluminum composite by the liquid-phase method is carried out.

Abstract: Aluminum-Air Batteries (AABs) are considered to be an attractive candidate as a energy storage technology due to their abundant raw material availability, high theoretical capacity, energy density, and safety. However, the development of these batteries is hindered by limited energy efficiency, primarily due to the high rate of self-corrosion of the aluminum anode in alkaline solutions, both under open-circuit conditions and during battery discharge. This research aims to enhance the performance of aluminum anodes in AABs by using commercials aluminum alloys as anodes and modifying their surfaces through the electrodeposition of zinc and manganese (Zn-Mn). The electrolyte used in this AAB is an alkaline solution consist of KOH 4M with 0,2M ZnO and 100mg/L CTAB as additive. The results show that electrodeposition was successfully conducted, leading to reduced corrosion rate as observed in linear polarization tests. Furthermore, electrodeposition contributed to increase battery cycle life, capacity discharge and energy discharge, as demonstrated by charge-discharge tests.

Abstract: This work presents the mechanical behavior of additive-manufactured AlSiMg alloy after severe plastic deformation (SPD). Equal Channel Angular Extrusion/Pressing (ECAE/P) is a well-known SPD method used for mechanical property improvement via grain refinement in metals. In this study, 8 pass ECAP at 250°C ECAP process is conducted on AlSi₁₀Mg which is manufactured by laser powder bed fusion (LPBF). Tensile tests were conducted at room temperature and at various strain rates to measure the strain rate sensitivity (SRS). With varying strain rate, there was appreciable change in the flow stress levels indicating that the severely deformed alloy exhibits negative SRS. Possible reasons for this mechanical response are explained based on the evolved microstructure to shed light on the parameters governing SRS in additive-manufactured alloys subjected to SPD.

Abstract: Friction is one of the key parameters in sheet metal forming. During forming process, the surface of aluminum sheet undergoes flattening and roughening, leading to changes in real area of contact and therefore friction between tool and workpiece. Predicting real area of contact based on the loading condition is fundamental to model friction in a forming process. For this purpose, we designed a setup to conduct the combined normal load – bulk strain experiments on two different aluminum grades. The real area of contact for each sample was measured and characterized using the surface height probability density distribution. The results show that strain can significantly affect the real area of contact in both A6016 and A5182 grades.

Abstract: In this study, low-thermal emissivity coatings were developed using aluminum leafing particles dispersed in an acrylic binder. The aluminum particles were modified through a ball milling process to enhance their leafing properties, with milling times ranging from 5 to 15 h. The effects of milling time on particle size, morphology, and leafing degree were examined using scanning electron microscopy (SEM) and laser diffraction analysis. Coatings with different particle volume concentrations (PVC) and thickener contents were prepared, and their thermal emissivity was evaluated. Results showed that milling time significantly affected the leafing behavior of the aluminum particles, with longer milling times leading to improved dispersion and lower emissivity values. The addition of a thickener enhanced particle distribution, but excessive concentrations resulted in void formation due to hindered solvent evaporation. The lowest thermal emissivity was achieved at a milling time of 15 hours and 10% PVC, providing valuable insights for the design of effective low-emissivity coatings for thermal management applications.

Abstract: Aluminum (Al) has emerged to become one of the potential anode materials candidates in metal-based batteries due to its abundant resource, inexpensive cost, good safeness and high theoretical energy density. However, thoughtful challenges have been barrier towards huge progress, including easy aluminum hydroxide formation, low practical voltage, and high corrosion rate. To approach those problems, this article proposes to enhance the electrochemical performance of anode side through electrodeposition of Zn-Mn on aluminum surface. The deposition of Zn-Mn consists of citrate and ethylenediaminetetraacetic acid (EDTA) as complexing agent to control the process rate. The effect of various deposition time, 0, 10, and 30 minutes, will be investigated by linear polarization, linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy measurements. The electrochemical measurement exhibits the deposition effect, minimized the impedance of Al surface and improved the electrochemical reactions. Moreover, the appearance of Zn-Mn layer has prolonged the discharge performance with battery analyzer measurements. Therefore, energy density increased from 1270.52 to 3327.68 mWh g^-1Al and the specific capacity enhances from 2779.908 to 7291.651 mAh g^-1. All the measurements applied 3.5% sodium chloride (NaCl). These results pose the electrical performance enhancement from the anode side, but the development of other sides is also necessary.

Abstract: Adhesive bonding is often found for engineering construction technology applications in industries such as aeronautics, automotive, electronics, and aerospace. Single lap joint type connections can be applied to dissimilar materials so that they can reduce the weight of construction. The objective of this study to determine the effects of adding natural latex adhesive to aluminum-cocofiber composites single lap joints. The research material uses two types of adherend, namely aluminum and cocofiber-reinforced composite with an Unsaturated Polyester matrix (UPRs) type Yukalac BQTN with a MEXPO catalyst. Adhesive bonding material uses epoxy resin and the addition of natural latex. The connection is carried out using a single lap joint adhesive bonding method between two different adherend materials. The adhesive material in the single lap joint is 0.2 mm thick using variations in the addition of natural latex adhesive to epoxy with variations of 5%NK: 95%EP, 15%NK: 85%EP, 25%NK: 75%EP, and 35%NK: 65%E.P. The adherend surface treatment was given by roughing the surface with sandpapering grid #150. The single lap joints shear test refers to ASTM D-1002. The test results indicated that the shear strength increases with the addition of 5% natural latex to the epoxy. The roughness treatment applied to the surface provides an irregular effect, thus increasing the bond between the adhesive and the adherend. In addition, it also improves the mechanical interlocking of the single lap joint. The failure modes after the shear stregth test that occur based on macro observations are cohesive, stock-break, thin layer cohesive, and fiber pull-out.