Search Results (4,244)

Alloys and metals exhibit high sensitivity to corrosion and aggressive environments. Hence, the development of protective treatments through accessible methods with a high degree of protection has become a necessity. This paper presents a method for treating the hydrophilic surface of aluminum alloys using two types of unsaturated fatty acids, thereby increasing the degree of hydrophobicity and protecting the material. The samples were cleaned by a chemical process, followed by immersion in oleic acid (C₁₈H₃₄O₂, 18:1 cis-9) and elaidic acid (C₁₈H₃₄O₂, 18:1 trans-9), and they were then treated at a temperature of 80 °C. Morphological and microstructural analyses were conducted using OM, FE-SEM, EDX, and FTIR to understand the influence of unsaturated monocarboxylic fatty acids on the alloy surfaces. The wettability capacity of the alloys was investigated by measuring the contact angle (CA). The results revealed that the cleaning step and modification treatment with fatty acids are essential steps for increasing the hydrophobic character of the surface. This study can be applied to various types of metallic substrates to enhance their corrosion resistance and long-term chemical stability in aggressive environments, making it adaptable for use in different industrial fields. Full article

Fin analysis is crucial to improve the rate of heat transfer. The main objective of this research is to investigate various fin designs in order to enhance the heat transfer efficiency of cooling fins through modifications in the geometry of the cylinder fins. The investigation of thermal analysis of the cylinder through variation in material, geometry, number, and size of the fins is carried out. Different materials are considered to design the fins, including cast iron, aluminum alloy 6061, and copper. The design of the engine, featuring various fins, is modeled with CATIA, and analysis is performed with ANSYS 2023 R2. The findings indicate that for the modified design-2, the total heat flux is more for aluminum alloy 6061 compared to the other two materials. Additionally, the use of aluminum alloy 6061 results in lower weight, making it a better choice compared to cast iron and copper. Full article

In resistance spot welding (RSW), the total electrical resistance (dynamic resistance) as the sum of bulk and contact resistance is a key variable. Both of these respective resistances influence the welding result, but the exact ratio to the total resistance of a real existing sheet is not known. Due to the high scatter in the RSW of aluminum alloys compared to steel, it is of interest to be able to explicitly determine the individual resistance components in order to gain a better understanding of the relationship between the initial state and the lower reproducibility of aluminum welding in the future. So far, only the total resistance and the bulk resistance could be determined experimentally. Due to the different sample shapes, it was not possible to consistently determine the contact resistance from the measurements. In order to realize this, a method was developed that contains the following innovations with the aid of simulation: determination of the absolute bulk resistance at room temperature (RT), determination of the absolute contact resistance at RT and determination of the ratio of bulk and contact resistance. This method makes it possible to compare the resistances of the bulk material and the surface in the initial state quantitatively. This now allows the comparison of batches regarding the surface resistance, especially for welding processes. For the aluminum sheets (EN AW-5182-O, EN AW-6014-T4) investigated, the method showed that the contact resistance dominates and the bulk resistance is less than 20%. These data can also be used to make predictions about the weldability of the alloy using artificial intelligence (AI). If experimental data are available, the method can also be applied to higher temperatures. Full article

TiAl alloy offers advantages including low density, high specific strength and stiffness, and excellent high-temperature creep resistance. It is widely used in the aerospace, automotive, and chemical sectors, as well as in other fields. However, at temperatures of 800 °C and above, it forms a porous oxide film predominantly composed of TiO₂, which fails to provide adequate protection. Applying high-temperature protective coatings is therefore essential. Oxides demonstrating protective efficacy at elevated temperatures include Al₂O₃, Cr₂O₃, and SiO₂. The Pilling–Bedworth Ratio (PBR)—defined as the ratio of the volume of the oxide formed to the volume of the metal consumed—serves as a critical criterion for assessing oxide film integrity. A PBR value greater than 1 but less than 2 indicates superior film integrity and enhanced oxidation resistance. Among common oxides, Al₂O₃ exhibits a PBR value within this optimal range (1−2), rendering aluminum-based compound coatings the most extensively utilized. Aluminum coatings can be applied via methods such as pack cementation, thermal spraying, and hot-dip aluminizing. Pack cementation, being the simplest to operate, is widely employed. In this study, a powder mixture with the composition Al:Al₂O₃:NH₄Cl:CeO₂ = 30:66:3:1 was used to aluminize γ-TiAl intermetallic compound specimens via pack cementation at 600 °C for 5 h. Subsequent isothermal oxidation at 900 °C for 20 h yielded an oxidation kinetic curve adhering to the parabolic rate law. This treatment significantly enhanced the high-temperature oxidation resistance of the γ-TiAl intermetallic compound, thereby broadening its potential application scenarios. Full article

Al-Mg-Si (6XXX) series aluminum alloys are widely applied in aerospace and transportation industries. However, exploring how varying compositions affect alloy properties and deformation mechanisms is often time-consuming and labor-intensive due to the complexity of the multicomponent composition space and the diversity of processing and heat treatments. This study, inspired by the Materials Genome Initiative, employs high-throughput experimentation—specifically the kinetic diffusion multiple (KDM) method—to systematically investigate how the pop-in effect, indentation size effect (ISE), and creep behavior vary with the composition of Al-Mg-Si alloys at room temperature. To this end, a 6016/Al-3Si/Al-1.2Mg/Al KDM material was designed and fabricated. After diffusion annealing at 530 °C for 72 h, two junction areas were formed with compositional and microstructural gradients extending over more than one thousand micrometers. Subsequent solution treatment (530 °C for 30 min) and artificial aging (185 °C for 20 min) were applied to simulate industrial processing conditions. Comprehensive characterization using electron probe microanalysis (EPMA), nanoindentation with continuous stiffness measurement (CSM), and nanoindentation creep tests across these gradient regions revealed key insights. The results show that increasing Mg and Si content progressively suppresses the pop-in effect. When the alloy composition exceeds 1.0 wt.%, the pop-in events are nearly eliminated due to strong interactions between solute atoms and mobile dislocations. In addition, adjustments in the ISE enabled rapid evaluation of the strengthening contributions from Mg and Si in the microscale compositional array, demonstrating that the optimum strengthening occurs when the Mg-to-Si atomic ratio is approximately 1 under a fixed total alloy content. Furthermore, analysis of the creep stress exponent and activation volume indicated that dislocation motion is the dominant creep mechanism. Overall, this enhanced KDM method proves to be an effective conceptual tool for accelerating the study of composition–deformation relationships in Al-Mg-Si alloys. Full article

The dispersion behavior of ceramic particles in aluminum alloys during rapid solidification critically affects the resulting microstructure and mechanical performance. In this study, we investigated the nucleation and growth of Al₃(Sc,Zr) on TiB₂ surfaces in a 2TiB₂/Al–8Ni–0.6Sc–0.1Zr alloy, fabricated via wedge-shaped copper mold casting and laser surface remelting. Thermodynamic calculations were employed to optimize alloy composition, ensuring sufficient nucleation driving force under rapid solidification conditions. The results show that the formation of Al₃(Sc,Zr)/TiB₂ composite interfaces is highly dependent on cooling rate and plays a pivotal role in promoting uniform TiB₂ dispersion. At an optimal cooling rate (~1200 °C/s), Al₃(Sc,Zr) nucleates heterogeneously on TiB₂, forming core–shell structures and enhancing particle engulfment into the α-Al matrix. Orientation relationship analysis reveals a preferred (111)α-Al//(0001)TiB₂ alignment in Sc/Zr-containing samples. A classical nucleation model quantitatively explains the observed trends and reveals the critical cooling-rate window for composite interface formation. This work provides a mechanistic foundation for designing high-performance aluminum-based composites with uniformly dispersed reinforcements for additive manufacturing applications. Full article

Secondary hypereutectic Al-Si alloys are attractive for sustainable manufacturing, yet their application is often limited by low strength and electrical conductivity due to impurity-induced microstructural defects. Achieving a balance between mechanical and conductive performance remains a significant challenge. In this work, nickel-coated carbon nanotubes (Ni-CNTs) were introduced into secondary Al-20Si alloys to tailor the microstructure and enhance properties through interfacial engineering. Composites containing 0 to 0.4 wt.% Ni-CNTs were fabricated by conventional casting and systematically characterized. The addition of 0.1 wt.% Ni-CNTs resulted in the best combination of properties, with a tensile strength of 170.13 MPa and electrical conductivity of 27.60% IACS. These improvements stem from refined α-Al dendrites, uniform eutectic Si distribution, and strong interfacial bonding. Strengthening was achieved through grain refinement, Orowan looping, dislocation generation from thermal mismatch, and the formation of reinforcing interfacial phases such as AlNi₃C₀.₉ and Al₄SiC₄. At higher Ni-CNT contents, property degradation occurred due to agglomeration and phase coarsening. This study presents an effective and scalable strategy for achieving strength–conductivity synergy in secondary aluminum alloys via nanoscale interfacial design, offering guidance for the development of multifunctional lightweight materials. Full article

Image processing has been widely adopted as an effective technology for analyzing weld forming quality which is greatly affected by the welding process parameters. In this paper, an L₂₅(5³) orthogonal experiment is designed to investigate the effects of welding process parameters on the weld forming quality in laser welding of aluminum alloy. The weld characteristics including the weld width (WW), weld penetration (PD), weld area (WA) and weld porosity (WP) under the conditions of the different welding process parameters consisting of the laser power (LP), welding speed (WS) and defocus distance (DD) are extracted from the laser welding experiment based on image processing. The effectiveness of the weld characteristics extraction method is verified by comparing the extracted results with the measured results. It is found that the WW, PD and WA are all significantly influenced by the LP among the three welding process parameters while the influences of the three process parameters on the WP are insignificant. The DD has a significant influence on the PD and the WS has a significant influence on the WA. The corresponding significance of influence is lower than the significance of influence of LP. The analysis results are conducive to the optimization of laser welding process parameters and improvement of welding quality. Full article

Cr/Ti bilayer coatings were deposited on 7050 aluminum alloy via magnetron sputtering at substrate temperatures of room temperature (RT), 150 °C, and 300 °C to investigate temperature effects on microstructure, hardness, and corrosion resistance. All coatings exhibited Cr(110) and Ti(002) phases. Temperature significantly modulated corrosion resistance by altering pore density, grain boundary density, and passivation film composition. Increasing temperature from RT to 150 °C raised corrosion rates primarily due to increased pore density. Further increasing to 300 °C reduced corrosion rates mainly through decreased grain boundary density, while passivation film composition changes altered electrochemical reaction kinetics. Substrate-coating interface defect density primarily influenced hardness with minimal effect on corrosion. Consequently, the RT-deposited coating, despite lower hardness, demonstrated optimal corrosion resistance: polarization resistance (7.17 × 10⁴ Ω·cm²), charge transfer resistance (12,400 Ω·cm²), and corrosion current density (2.47 × 10⁻⁷ A/cm²), the latter being two orders of magnitude lower than the substrate. Full article

Understanding the limitations of cold-formed aluminum alloys in practice applications is essential, particularly due to the risk of substructural changes and a reduction in strength when exposed to elevated temperatures. In this study, the thermal stability of the ultra-fine-grained (UFG) structure formed by equal channel angular pressing (ECAP) at room temperature and the mechanical properties of the AlSi7MgCu0.5 alloy were investigated. Prior to ECAP, the plasticity of the as-cast alloy was enhanced by a heat treatment consisting of solution annealing, quenching, and artificial aging to achieve an overaged state. Four repetitive passes via ECAP route A resulted in the homogenization of eutectic Si particles within the α-solid solution, the formation of ultra-fine grains and/or subgrains with high dislocation density, and a significant improvement in alloy strength due to strain hardening. The main objective of this work was to assess the microstructural and mechanical stability of the alloy after post-ECAP annealing in the temperature range of 373–573 K. The UFG microstructure was found to be thermally stable up to 523 K, above which notable grain and/or subgrain coarsening occurred as a result of discontinuous recrystallization of the solid solution. Mechanical properties remained stable up to 423 K; above this temperature, a considerable decrease in strength and a simultaneous increase in ductility were observed. Synchrotron radiation X-ray diffraction (XRD) was employed to analyze the phase composition and crystallographic characteristics, while transmission electron microscopy (TEM) was used to investigate substructural evolution. Mechanical properties were evaluated through tensile testing, impact toughness testing, and hardness measurements. Full article

Al-xSi-35Ge (x = 4, 6, 8, 10, 12, wt.%) filler metals were prepared to vacuum braze 6061 aluminum alloy. The wettability of filler metals was studied. A thermodynamics model of the Al-Si-Ge ternary alloy was established to analyze the mechanism and impact of Si in the microstructure of the brazed joint. The findings indicated that Si addition had a slight effect on the melting point of Al-xSi-35Ge filler metals. Great molten temperature region of fillers was responsible for the loss of Ge during the wetting process, making residual filler metal difficult to melt. The microstructure of the joint was characterized by a multilayer structure that was primarily composed of three zones: two transition regions (Zone I) and a filler residual region (Zone II). There was liquidation of filler metal for Al-Si-35Ge filler metals during brazing, resulting in holes and cracks in joints. Increasing the Si content in fillers could alleviate the liquidation of filler metal, owing to diminishing difference of chemical potential of Ge (μ_Ge) in fillers and 6061 substrates, hindering the diffusion of Ge from filler metal to substrates. Full article

Aluminum matrix composites provide an ideal solution for lightweight brake disks, but conventional casting processes are prone to crack initiation due to inhomogeneous reinforcement dispersion, gas porosity, and inadequate toughness. To break the conventional trade-off between high wear resistance and low toughness of brake disks, this study fabricated a bimetallic structure of SiC_p/Al–Fe–V–Si aluminum matrix composite and cast ZL101 alloy using friction stir lap welding (FSLW). Then, the microstructural evolution, mechanical properties, and tribological behavior of the FSLW joints were studied by XRD, SEM, TEM, tensile testing, and tribological tests. The results showed that the FSLW process homogenized the distribution of SiC particle reinforcements in the SiC_p/Al–Fe–V–Si composites. The Al₁₂(Fe,V)₃Si heat-resistant phase was not decomposed or coarsened, and the mechanical properties were maintained. The FSLW process refined the grains of the ZL101 aluminum alloy through recrystallization and fragmented eutectic silicon, improving elongation to 22%. A metallurgical bond formed at the joint interface. Tensile fracture occurred within the ZL101 matrix, demonstrating that the interfacial bond strength exceeded the alloy’s load-bearing capacity. In addition, the composites exhibited significantly enhanced wear resistance after FSLW, with their wear rate reduced by approximately 40% compared to the as-received materials, which was attributed to the homogenized SiC particle distribution and the activation of an oxidative wear mechanism. Full article

We simulate the dispersoid distribution within the Al matrix grains of an aluminum 6082 alloy by combining finite difference cell modeling with mean-field precipitation simulations. The results demonstrate that the initial as-cast microstructure and the heating rate during the ramp-up to the isothermal homogenization temperature are the most important factors governing the dispersoid particle distribution. The simulation results are validated by Electron Probe Microanalysis (EPMA) and Optical Microscopy on experimental run products. The results indicate that dispersoids can only achieve uniform distribution throughout the grain when the heating rate to the homogenization temperature is sufficiently slow. Full article

The development of technology has driven a rising need for high-accuracy and high-efficiency manufacturing of low-volume products. Incremental forming technology, characterized by die-free flexibility and low production costs, can effectively replace stamping processes for manufacturing customized small-batch products. However, high-performance aluminum alloys generally exhibit poor room-temperature plasticity but excellent high-temperature plasticity, necessitating the integration of thermal-assisted methods for manufacturing such products. However, the temperature of the forming region will excessively rise without temperature control, which will affect the forming performance of the material in hot incremental sheet forming of AA2024-T4 aluminum alloy. This study focuses on AA2024-T4 aluminum alloy and proposes a uniform temperature control method for the electric hot tube-assisted incremental sheet forming process, incorporating an adaptive fuzzy PID algorithm. The temperature difference of the forming region is lower than 6% under the various temperatures. On this basis, the forming limit angle and the microstructure state of the material are analyzed, and the grain feature of the material exhibits significantly refined grains and the uniform fine grain distribution under 180 °C with the temperature control of the adaptive fuzzy PID algorithm. Full article

This study investigates the friction stir joining of AA6082-T6 aluminum alloy and Noryl GFN2 polymer in a buttstrap configuration, targeting the development of lightweight cylindrical-shaped structures where the polymer provides thermal, chemical, and electrical insulation, while the aluminum ensures mechanical integrity. A parametric analysis was carried out to assess the ability to produce friction stir buttstrap composite panels in a single processing step and assess the resulting tensile and flexural behavior. To that end, travel and rotating speeds ranging from 2150 to 2250 rpm, and 100 to 140 mm/min, respectively, were employed while keeping plunge depth and the tilt angle constant. A total of nine composite joints were successfully produced and subsequently subjected to both tensile and four-point bending tests. The tensile and flexural strength results ranged from 80 to 139 MPa, and 39 to 47 MPa, respectively. Moreover, the microstructural examination revealed that all joints exhibited a defect within the joining region and its size and shape had a significant effect on tensile strength, whereas the flexural strength was less affected with more uniform results. The joining region was also characterized by a decrease in hardness, particularly in the pin-affected region on the aluminum end of the joint, exhibiting a W-shaped pattern. Contrarily, on the polymeric end of the joining region, no significant change in hardness was observed. Full article