Search Results (6,731)

The 7000 series aluminum alloy represented by Al-Zn-Mg-Cu has good strength and toughness and is widely used in the aerospace field. However, its high Zn content results in poor corrosion resistance, limiting its application in other fields. In order to achieve the synergistic improvement of both strength and corrosion resistance, this study examines the response of strength, toughness and corrosion resistance of a high-strength aluminum alloy tail frame under aging conditions with external stresses of 135 MPa, 270 MPa and 450 MPa. The results show that with the increase in the external stress level, the strength of the alloy improves, while its corrosion resistance decreases. An optimal balance of strength, toughness and corrosion resistance is achieved at the conditions of 270 MPa-120–24 h. This phenomenon can be attributed to two main factors: first, lattice defects such as vacancy and dislocation are introduced into the stress aging process. The introduction of a vacancy makes it easier for neighboring solute atoms to migrate there. This makes the crystal precipitates more dispersed. Also, the number of precipitates in the matrix increases from 2650 to 3117, and the size is refined from 2.96 nm to 2.64 nm. At the same time, the dislocation entanglement within the crystal structure promotes the dislocation strengthening mechanism and promotes the solute atoms to have enough channels for migration. Since too many dislocations can cause the crystal to become brittle and thus reduce its strength, entangled dislocations hinder the movement of the dislocations, thereby increasing the strength of the alloy. Secondly, under the action of external force, the precipitated phase is discontinuous, which hinders the corrosion expansion at the grain boundary, thus improving the corrosion resistance of the alloy. At low-stress states, the binding force of vacancy is stronger, the precipitation free zone (PFZ) is significantly inhibited, and the intermittent distribution effect of intergranular precipitates is the most obvious. As a result, the self-corrosion current decreases from 1.508 × 10⁻⁴ A∙cm⁻² in the non-stress state to 1.999 × 10⁻⁵ A∙cm⁻², representing an order of magnitude improvement. Additionally, the maximum depth of intergranular corrosion is reduced from 274.9 μm in the non-stress state to 237.7 μm. Full article

The Ti-6Al-4V alloy is widely utilized in the aerospace industry for applications such as turbine blades, where it is valued for its mechanical strength at high temperatures, low specific gravity, and resistance to corrosion and oxidation. This alloy provides crucial protection against oxidation and thermal damage. A thermal barrier coating (TBC) typically consists of a metallic substrate, a bond coating (BC), a thermally grown oxide (TGO), and a topcoat ceramic (TC). This study aimed to investigate laser parameters for forming a TBC with a NiCrAlY bond coating and a zirconia ceramic topcoat, which contains 16.0% equimolar yttria and niobia. The coatings were initially deposited in powder form and then irradiated using a CO₂ laser. The parameters of laser power and beam scanning speed were evaluated using scanning electron microscopy and X-ray diffraction. The results indicated that the optimal laser scanning speed and power for achieving the best metallurgical bonding between the substrate/BC and the BC-TGO/TC layers were 70 mm/s at 100 W and 550 mm/s at 70 W, respectively. Laser-based layer formation has proven to be a promising technique for the application of TBC. Full article

The present study involved (TiB + TiC)/TC11 (Ti-6.5Al-3.5Mo-1.2Zr-0.3Si) + xFe titanium matrix composites (TMCs) reinforced by in situ TiB whiskers and TiC particles fabricated by hot isostatic pressing. Microstructure observation reveals a substantial distribution of in situ reinforcements, which form a network-reinforced structure at the prior particle boundaries of the TC11 matrix. The micro–nanoscale TiB whiskers and TiC particles within and surrounding this network serve as effective dislocation pinning. The enhancement of mechanical properties can be attributed to load-bearing strengthening, fine-grain strengthening, and dislocation strengthening. The hardness and compressive strengths were investigated through mechanical properties testing. The hardness increased by 19.4% (2 wt% B₄C-reinforced composites) compared with TC11 alloy. However, the addition of 2 wt% Fe at the same B₄C level (2 wt% B₄C + 2 wt% Fe-reinforced composites) resulted in a significant increase in hardness by 37.5% and 15.2% in compressive strengths of TMC and can be attributed to the solid solution strengthening effect and higher dislocation density provided by the addition of Fe. In addition, the optimal overall properties can be achieved by strictly regulating the addition ratio of 2 wt% Fe and 1 wt% B₄C, allowing for a compressive strength of 2301 MPa while still maintaining a compressive strain of 24.6%. Full article

The metastable β-Ti21S alloy exhibits a lower elastic modulus than Ti-6Al-4V ELI while maintaining high mechanical strength and ductility. To address stress shielding, this study explores the integration of lattice structures within prosthetics, which is made possible through additive manufacturing. Continuous adhesion between the implant and bone is essential; therefore, auxetic bow-tie structures with a negative Poisson’s ratio are proposed for regions under tensile stress, while Triply Periodic Minimal Surface (TPMS) structures with a positive Poisson’s ratio are recommended for areas under compressive stress. This research examines the manufacturability and quasi-static mechanical behaviour of two auxetic bow-tie (AUX 2.5 and AUX 3.5) and two TPMS structures (TPMS 2.5 and TPMS 1.5) in β-Ti21S alloy produced via laser powder bed fusion. Micro-CT reveals printability issues in TPMS 1.5, affecting pore size and reducing fatigue resistance compared to TPMS 2.5. AUX 3.5’s low stiffness matches cancellous bone but shows insufficient yield strength and fatigue resistance for femoral implants. Biological tests confirm non-toxicity and enhanced cell activity in β-Ti21S structures. The study concludes that the β-Ti21S alloy, especially with TPMS 2.5 structures, demonstrates promising mechanical and biological properties for femoral implants. However, challenges like poor printability in TPMS 1.5 are acknowledged and should be addressed in future research. Full article

The development of beta titanium alloys with biocompatible elements to replace Al and V is a subject of significant interest in the biomedical industry. This approach aims to enhance biocompatibility and mitigate potential cytotoxic effects associated with traditional alloying elements. In this work, Ti–xNb–ySi alloys were produced using powder metallurgy, with x of 35, 40, and 45 wt.%, and y of 0.10, 0.35, and 0.60% wt.%, using a $3^2$ experimental design. Milling was used to mix and disperse the powders, followed by cold pressing, sintering, and heat treatment. Nb was the main element used to stabilize the β phase, and Si was used to form Si precipitates, although Si also exhibits a β-stabilizing effect. It was found that an increase from 0.10 to 0.35 wt.% of Si improved relative density, with no benefits observed at 0.60 wt.% Si. Electron microscopy showed the presence of β phase grains, and grains with β + α intragranular structures and precipitates. Increasing Nb content resulted in a decrease in ultimate tensile strength while increasing Si content from 0.10% to 0.35 wt.% exhibited the opposite effect. Full article

Titanium potassium oxalate had been mixed into the electrolyte to improve the anti-corrosion property of the micro arc oxidation coating on the surface of the aluminium alloy. The surface and cross-section of the coating at different titanium potassium oxalate concentrations had been observed by scanning electron microscopy, showing that when the titanium potassium oxalate concentration was 10 g/L, the coating compactness was better. Additionally, the element content of the coating had been studied by the energy dispersive spectrometer, and results proved that the coating consisted of Al, O, Ti, Si, and P. The Ti increased with the increase in titanium potassium oxalate concentration. The X-ray diffractometer had been employed to analyze the crystalline structure of the coating. Then, it was found that after the micro arc oxidation, an alumina oxide coating was prepared on the surface of the aluminium alloy, and the Al₂O₃ and TiO₂ characteristic peak was observed. Furthermore, the electrochemical workstation was used to test the anti-corrosion of the coating. It was proved that when the titanium potassium oxalate concentration was 10 g/L, the open circuit voltage, corrosion current, corrosion potential, and impedance of the coating were improved, and the anti-corrosion property of the aluminium alloy had been strengthened. Full article

To achieve carbon neutrality, a reduction in car body weight is essential. Multi-material structures that use lightweight materials such as carbon fiber-reinforced polymers (CFRP) and aluminum (Al) alloy are used to replace parts of steel components. This multi-material method requires specific joining techniques for bonding dissimilar materials. Friction stir spot welding (FSSW) is one of the joining techniques used for joining dissimilar materials, enabling rapid and strong joints. FSSW for bonding A5052 Al alloy and carbon fiber-reinforced thermosetting resin (CFRTS) utilizing composite laminates with integrally molded thermoplastic resin in the outermost layer has been developed. However, joints using this method cause pyrolysis due to excessive frictional heating at the tool’s bottom, which may affect joint strength and promote corrosion in Al alloy. Therefore, this study developed new tools, a concave-shaped tool without a probe, a concave-shaped tool with a probe and a conventional FSSW tool, and investigated the influence of heat distribution and joint strength using the three new tools. The newly developed concave-shaped tool with a probe suppressed 7% of maximum heat input, decreased the pyrolysis area of epoxy resin by 47%, and increased joint strength by 4%. Finite element analysis also showed the suppression of heat input through the newly developed concave-shaped tool with a probe, achieved by reducing the contact area between the tool and Al alloy. Full article

Based on the idea of integrated computational materials Engineering (ICME), this research applies a digital integrated computing platform integrating ProCAST and MATLAB software. The effects of Fe and Zn contents on the microstructure and properties of die-casting Al–10Si–Mg alloy was investigated through numerical simulation and experimental characterization. The results show that with Fe and Zn contents of 1.30 and 0.25 wt.%, respectively, the grain size and porosity of the die-cast parts are the smallest, and the yield strength and tensile strength are 203 MPa and 313 MPa, respectively. Compared with the addition of 0.14 wt.% Fe and 0.01 wt.% Zn, the increase was 16% and 15.5%, respectively. When the Fe content is higher than 1.30 wt.%, the size of the β-Al₅FeSi phase in the alloy matrix increases. Moreover, as the Fe content increases, the morphology of the β-Al₅FeSi transforms from elongated to a needle-like shape, which increases brittleness and reduces elongation, tensile strength, and yield strength. When 0.25 wt.% Zn is added, the segregation phenomenon of eutectic Si in the Al–10Si–Mg alloy is inhibited and the tensile strength and yield strength are improved. However, with the increase in Zn content to 0.95 wt.%, there is the coarsening of eutectic Si, resulting in a decreased elongation and decreased mechanical properties. The optimization method of the integrated computing platform greatly simplifies the computing cycle and improves work efficiency. Full article

Al-Mg alloy wire modified by Sc and Zr additions was used to prepare a high-strength, non-heat-treated Al-Mg alloy component by wire arc additive manufacturing (WAAM) technology in the present work, and the microstructure, mechanical properties, fatigue resistance, as well as their anisotropies of the deposited Al-Mg-Sc-Zr alloy component were studied. The results show that the microstructure of the as-deposited alloy is composed of fine equiaxed grains with an average grain size of around 8 μm, and nanosized Al₃(Sc, Zr) particles (~5 nm) are also evident. The tensile properties and fatigue resistance of the deposited alloy showed significant anisotropy, and the performance of the traveling direction is always better than that of the deposition direction. The ultimate strength, yield strength, elongation, and critical fatigue life (cycles) of the as-deposited alloy along the traveling direction (0° direction) are 362 ± 7 MPa, 244 ± 3 MPa and 24.8 ± 0.3%, and 1.72 × 10⁵, respectively. The presence of weak bonding areas and high tensile (positive) residual stress between the deposition layers deteriorate the tensile properties and critical fatigue life of the sample along the deposition direction. Full article

High-entropy alloy (HEA) coatings have attracted wide scientific attention in academic research and industrial innovation. In the present paper, the NiCoCrAlY HEA coatings are successfully synthesized on the surface of M50 steel to improve the corrosion resistance and tribocorrosion resistance of M50 steel in salt-contaminated lubricating oil. The corrosion and tribocorrosion behaviors of M50 steel and NiCoCrAlY coatings are studied systemically under the same conditions. The experimental results show that NiCoCrAlY coatings have good, densified microstructures and improve effectively the corrosion resistance and tribocorrosion resistance of M50 steel because the protective passivation films and oxide films are formed on the surface of NiCoCrAlY coatings. NiCoCrAlY coatings have high corrosion potential, a low corrosion current density, and a corrosion rate that is comparable with M50 steel. The corrosion potential of M50 steel decreases and the corrosion current density increases with the increase in load due to wear-induced corrosion. The corrosion and tribocorrosion mechanisms of M50 steel and coatings are discussed in light of the experimental results. The wear mechanism of M50 steel is abrasive wear. It is accompanied by corrosion wear for M50 steel and oxidative wear for NiCoCrAlY coatings. Full article

The development of low-temperature piezoresistive materials provides compatibility with standard silicon-based MEMS fabrication processes. Additionally, it enables the use of such material in flexible substrates, thereby expanding the potential for various device applications. This work demonstrates, for the first time, the fabrication of a 200 nm polycrystalline silicon thin film through a metal-induced crystallization process mediated by an AlSiCu alloy at temperatures as low as 450 °C on top of silicon and polyimide (PI) substrates. The resulting polycrystalline film structure exhibits crystallites with a size of approximately 58 nm, forming polysilicon (poly-Si) grains with diameters between 1–3 µm for Si substrates and 3–7 µm for flexible PI substrates. The mechanical and electrical properties of the poly-Si were experimentally conducted using microfabricated test structures containing piezoresistors formed by poly-Si with different dimensions. The poly-Si material reveals a longitudinal gauge factor (GF) of 12.31 and a transversal GF of −4.90, evaluated using a four-point bending setup. Additionally, the material has a linear temperature coefficient of resistance (TCR) of −2471 ppm/°C. These results illustrate the potential of using this low-temperature film for pressure, force, or temperature sensors. The developed film also demonstrated sensitivity to light, indicating that the developed material can also be explored in photo-sensitive applications. Full article

This study investigates the effects of magnesium (Mg) content, silicon carbide (SiC) reinforcement, and aging temperature (AT) on the ultimate tensile strength (UTS) and Brinell hardness number (BHN) of eutectic Al-Si composites using a full factorial experimental approach. The analysis reveals that increasing Mg content from 0 wt% to 1.5 wt% significantly enhances UTS, likely due to solid solution strengthening and improved particle reinforcement. Similarly, a rise in SiC content up to 4 wt% leads to a notable increase in UTS, indicating effective matrix reinforcement. AT is crucial, with the highest UTS achieved at 100 °C; however, overaging at 200 °C results in reduced strength due to precipitate coarsening. Interaction plots demonstrate a synergistic effect between Mg and SiC, where higher levels of both contribute to a more substantial increase in UTS. The results also show that while both Mg and SiC improve UTS, their effects are optimized with appropriate aging conditions, although overaging diminishes these benefits. Analysis of variance (ANOVA) highlights that AT, Mg, and SiC each significantly impact UTS and BHN, with SiC having the greatest effect of 47.92% on hardness and AT having the greatest effect of 36.58% on the UTS. The interaction between SiC particles and AT is particularly influential on BHN. These findings emphasize the importance of carefully optimizing processing conditions to enhance the mechanical properties of eutectic Al-Si composites. Full article

Gallium oxide (Ga₂O₃) has gained considerable attention due to its wide bandgap, the availability of native substrates, and its excellent properties for solar-blind photodetectors, transparent electronics, and next-generation power devices. However, the expensive Ga₂O₃ native substrates have restricted its widespread adoption. To reduce costs and further the development of β-Ga₂O₃-based devices, there is a need for bandgap-tunable oxide films with high crystal quality for deep-ultraviolet (DUV) photodetectors and high-breakdown-field power devices. This study introduces a Thermal Interdiffusion Alloying method to address these requirements. It focuses on developing deep ultraviolet (DUV) photodetectors using β-Ga₂O₃ thin films on sapphire substrates by promoting the diffusion of aluminum (Al) atoms from the substrate into the film, resulting in the formation of aluminum gallium oxide (β-(Al_xGa_1−x)₂O₃). The aluminum content is controlled by adjusting the process temperature, allowing for tunable detection wavelengths and enhanced DUV sensing capabilities. Radio frequency (RF) sputtering optimizes the film’s quality by adjusting the sputtering power and the argon/oxygen (Ar/O₂) flow ratio. Material analysis indicates that this method expands the optical bandgap and shifts the response wavelength to 210 nm, significantly boosting the performance of the fabricated photodetectors. This research presents considerable potential for advancing DUV photodetectors across various disinfection applications. Full article

Copper matrix composites (Cu-MCs) have garnered significant attention due to their exceptional electrical, wear-resistant, and mechanical properties. Among them, Al₂O₃/Cu composites, reinforced with Al₂O₃, are a focal point in the field of high-strength, high-conductivity copper alloys, owing to their high strength, excellent electrical conductivity, and superior resistance to high-temperature softening. Cold deformation is an effective method for enhancing the mechanical properties of Al₂O₃/Cu composites. However, during cold deformation of large-cross-sectional Al₂O₃/Cu composites, the inhomogeneity in microstructure and properties induced by varying stress states cannot be overlooked. In this study, cold deformation of 1.12 wt% Al₂O₃/Cu large-cross-sectional composites was performed using a rolling process, coupled with finite element numerical simulations, to investigate the distribution characteristics of microstructure and properties during the rolling process. The results indicate that under cold deformation, the hardness of the material increases linearly from the surface layer to the core, while the change in electrical conductivity is minimal. The increase in hardness is closely related to variations in dislocation density and grain size, with dislocation density being the dominant strengthening mechanism. Quantitative analysis reveals that strain inhomogeneity during cold deformation is the primary cause of microstructural differences, leading to variations in mechanical properties at different positions. This study provides a theoretical basis for understanding the inhomogeneity of cold deformation in large-sized Al₂O₃/Cu composites and for controlling their microstructure–property relationships. Full article

Traditional defect recovery methods rely on high-temperature annealing, often exceeding 750 °C for FeCrAl. In this study, we introduce electron wind force (EWF)-assisted annealing as an alternative approach to mitigate irradiation-induced defects at significantly lower temperatures. FeCrAl samples irradiated with 5 MeV Zr²⁺ ions at a dose of 10¹⁴ cm⁻² were annealed using EWF at 250 °C for 60 s. We demonstrate a remarkable transformation in the irradiated microstructure, where significant increases in kernel average misorientation (KAM) and low-angle grain boundaries (LAGBs) typically indicate heightened defect density; the use of EWF annealing reversed these effects. X-ray diffraction (XRD) confirmed these findings, showing substantial reductions in full width at half maximum (FWHM) values and a realignment of peak positions toward their original states, indicative of stress and defect recovery. To compare the effectiveness of EWF, we also conducted traditional thermal annealing at 250 °C for 7 h, which proved less effective in defect recovery as evidenced by less pronounced improvements in XRD FWHM values. Full article