Search Results (479)

7xxx series aluminum alloys are critical structural materials in aerospace applications, but their susceptibility to hydrogen embrittlement (HE) poses significant challenges to service safety and durability. The effects of Si, Er, and Zr microalloying, combined with optimized heat treatments on the HE resistance of Al–Zn–Mg–Cu alloys, were systematically investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and mechanical testing. Three alloys—1# (AlZnMgCuZr), 2# (AlZnMgCuErZr), and 3# (AlZnMgCuSiErZr)—were subjected to single-stage or two-stage homogenization, followed by solution treatments at 470 °C/2 h and 540 °C/1 h, and peak aging at 125 °C. The hydrogen charging experiment was conducted by first applying a modified acrylic resin coating to protect the gripping sections of the specimen, followed by a tensile test. Results demonstrate that alloy 3# with Si addition exhibited the lowest RA_loss, followed by the 2# alloy, which effectively improved the alloys’ hydrogen embrittlement behavior. Compared with the solution in 470 °C/2 h, the 540 °C/1 h solution treatment enabled complete dissolution of Mg₂Si phases, promoting homogeneous precipitation and peak hardness comparable to alloy 2#. Two-stage homogenization significantly enhanced the number density and refinement of L₁₂-structured Al₃(Er,Zr) nanoprecipitates. Silicon further accelerated the precipitation kinetics, leading to more Al₃(Er,Zr) nanoprecipitates, finely dispersed T′/η′ phases, and lath-shaped GPB-II zones. The GPB-II zones effectively trapped hydrogen, thereby improving HE resistance. This work provides a viable strategy for enhancing the reliability of high-strength aluminum alloys in hydrogen-containing environments. Full article

Rare-earth aluminum alloy materials exhibit excellent strength, plasticity, and toughness at room temperature, making them easily meet the lightweight requirements of structural components, and high-temperature plastic forming is widely applied. Accordingly, the present study is dedicated to investigating the rheological characteristics of rare-earth aluminum alloys subjected to tensile deformation at elevated temperatures. High-temperature tensile tests were implemented across a temperature interval of 623 to 723 K and a strain rate spectrum ranging from 0.01 to 1.0 s⁻¹. Experimental outcomes reveal that the flow stress exhibits a downward trend with the elevation in deformation temperature as well as the reduction in strain rate. It is also confirmed that flow stress correlates closely with the evolution of strain, which further motivates the construction of a modified Arrhenius constitutive equation integrated with strain compensation. Nevertheless, it is noted that the predictive precision of the strain-compensated Arrhenius constitutive model declines remarkably once the applied strain exceeds the scope covered by the experiments. Through error analysis, it was revealed that the material parameters of the Arrhenius-type constitutive model are influenced by strain, strain rate, and deformation temperature. On this basis, an optimized Arrhenius constitutive model was proposed in the current research. The parameter fitting was accomplished by comparing the calculated stresses from the model with experimental data, which involved strain compensation and a comprehensive consideration of the effects of temperature and strain rate. The resulting model is capable of precisely describing the material’s flow behavior within the experimental strain range and effectively predicting it beyond that range. Full article

Antibacterial thin-film coatings are of increasing interest for enhancing hygiene in controlled environments such as commercial greenhouses. Phytopathogens including Pseudomonas syringae, and human pathogens such as Escherichia coli, Micrococcus luteus, and Staphylococcus aureus, frequently contaminate greenhouse environments. The present study aimed to develop and evaluate multifunctional magnetron-sputtered glass coatings with strong antimicrobial performance, deposited by physical vapor deposition to achieve precise control of film composition and uniform coverage of large substrates (≥0.25 m²), ensuring industrial-scale applicability. Thin films were fabricated by magnetron sputtering using multi-alloy targets composed of Cu, Sn, Zn, Al, Ni, Fe, Ti, Mn, Nb, or Co. Fourteen distinct coating compositions were characterized using high-resolution transmission electron microscopy, scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Antibacterial performance was evaluated against the following strains: E. coli (PCM 2560), M. luteus (PCM 525), S. aureus (PCM 2602), and P. syringae pv. tomato (IOR2146). Coatings prepared from 90%Cu-10%Sn, 90%Cu-10%Zn, and 80%Cu-20%Ti targets exhibited one of the highest antibacterial efficiencies. These coatings also showed strong mechanical durability and corrosion resistance. Our results indicate that coatings obtained from Cu-based multi-alloy targets by magnetron sputtering are promising candidates for use as durable, antimicrobial inner glass surfaces in future greenhouse applications. Full article

Aluminum–based brazing alloys have been developed for joining 7072 high–strength aluminum alloys. However, challenges related to their high melting points and joint softening still require further exploration. This study employs a combination of first–principles calculations and experimental techniques to examine the microstructure and mechanical properties of 7072 aluminum alloy joints brazed with (Ni, Y)–modified Al–Si–Cu–Zn filler alloys. Through the virtual crystal approximation (VCA) method, it was observed that the Al–10Si–10Cu–5Zn–xNi–yY (x = 0, 1.0, 2.0, 3.0, y = 0.2, 0.4, 0.6) filler alloy exhibits excellent mechanical stability, combining both high strength and reasonable ductility. Seven brazed joint samples with varying Ni and Y contents were fabricated using melting brazing and analyzed. The findings showed that Ni reduces the liquidus temperature of the filler, narrowing the melting range. This facilitates the conversion of the brittle Al₂Cu phase into a more ductile Al₂(Cu,Ni) phase, thus enhancing joint strength. Y acts as a heterogeneous nucleation site, promoting local undercooling, increasing the nucleation rate, and refining the microstructure. When the Ni content was 2.0 wt.% and the Y content was 0.4 wt.%, the tensile strength of the brazed joint reached a peak value of 295.1 MPa. Computational predictions align with the experimental results, confirming that first–principles calculations are a reliable method for predicting the properties of aluminum alloy brazing materials. Full article

Existing experiments have shown that in Al-Zn-Mg-Cu alloys, solute Cu, when substituting for Al atoms, can enter the interior of ${\eta }^{\prime }$ precipitate, changing its composition significantly, but the mechanical properties of the ${\eta }^{\prime }$ compound containing dissolved Cu has not yet been explored. In this study, we conducted a theoretical prediction to investigate the effect of dissolved Cu on the mechanical properties of the ${\eta }^{\prime }$ compound (Al₄Mg₂Zn₃). The results indicate that Cu, substituted for Al, tends to reduce the volume, increase the hardness, and raise the Debye temperature of the ${\eta }^{\prime }$ crystal. Although dissolved Cu weakly increases the brittleness of the crystal, the ${\eta }^{\prime }$ still retains its ductile nature. Additionally, we simulated the surface structure of the (0001) surface and discovered that there are five distinct surface terminations, namely Al1, Al2, Mg1, Mg2, and Zn. Exact calculations reveal that the surface energies of different terminations are influenced not only by the electronic structure of the surface atoms but also by the distance between the surface layer and the sub-surface layer of the corresponding surface supercell. Full article

Extrusion of AlZnMgCu alloys is associated with a very high plastic resistance of the materials at forming temperatures and significant friction resistance, particularly at the contact surface between the ingots and the container. In technological practice, this translates into high maximum extrusion forces, often close to the capacity of hydraulic presses, and the occurrence of surface cracking of extruded profiles, resulting in a reduction in metal exit speed (production process efficiency). The accuracy of mathematical material models describing changes in the plastic stress of a material as a function of deformation, depending on the forming temperature and deformation speed, plays a very important role in the numerical modelling of extrusion processes using the finite element method (FEM). Therefore, three mathematical material models of the tested aluminium alloy were analysed in this study. In order to use the results of plastometric tests determined on the Gleeble device, they were approximated with varying degrees of accuracy using the Hnsel–Spittel equation and then implemented into the material database of the QForm-Extrusion^® programme. A series of numerical FEM calculations were performed for the extrusion of Ø50 × 3 mm tubes made of 7075 aluminium alloy using chamber dies for two different billet heating temperatures, 480 °C and 510 °C, and for three different material models. The metal flow was analysed in terms of geometric stability and dimensional deviations in the wall thickness of the extruded tube and its surface quality, as well as the maximum force in the extrusion process. Experimental studies of the industrial extrusion process of the tubes, using a press with a maximum force of 28 MN and a container diameter of 7 inches, confirmed the significant impact of the accuracy of the material model used on the results of the FEM numerical calculations. It was found that the developed material model of aluminium alloy 7075 number 1 allows for the most accurate representation of the actual conditions of deformation and quality of extruded tubes. Moreover, the material data obtained on the Gleeble simulator made it possible to determine the limit temperature of the extruded alloy, above which the material loses its cohesion and cracks appear on the surface of the extruded profiles. Full article

CuZn39Pb3 leaded brass is one of the most widely used alloys in machining, with a 100% machinability index. However, there has been a lack of research on the effects of coldworking on surface integrity (SI) and operating behaviour of CuZn39Pb3 components. This study addresses this knowledge gap by examining the effects of three optimised combined processes on surface roughness, a key SI characteristic. Specifically, samples were subjected to a turning process followed by diamond burnishing (DB); this combined process was performed under three conditions: conventional flood lubrication (F), dry (D), and dry and cool-assisted (D+C) conditions. Cool-assisted conditions were achieved using a special device with a cold air nozzle operating on the vortex tube principle. The D and D+C conditions represent environmentally sustainable alternatives because they eliminate the use of cutting fluids, thereby reducing their adverse effects on both the environment and human health. The resulting surfaces obtained after each of the three optimised combined processes (F, D, and D+C) exhibited mirror-like finishes with minimum average roughness Ra values of 0.054, 0.079, and 0.082 μm, respectively. In addition, the F- and D+C-processes resulted in surface profiles with negative skewness and kurtosis values greater than three. Since roughness shape parameters are known to influence the operating behaviour of machined components, these processes are suitable for improving wear resistance in boundary lubrication regimes. Full article

To address the technical challenge of balancing formability and strength in automotive aluminum alloys, this study examined an Al-4.35Mg-3.6Zn-0.2Cu alloy subjected to a combined heat-treatment schedule consisting of a two-step solution treatment (470 °C for 24 h followed by 460 °C for 30 min) and a subsequent two-step aging process (T4P: 80 °C for 12 h, followed by BH: 180 °C for 30 min). Microstructural evolution was characterized using transmission electron microscopy, and uniaxial tensile tests were performed in accordance with the GB/T 228.1-2021 standard at a strain rate of 0.2 mm/min. In the T4P condition, the matrix contained both GPI zones (~0.9 nm) and GPII zones (~1.2 nm), with no detectable T-phase precipitation. The presence of GPII zones enhanced ductility by promoting dynamic recovery after dislocation shearing, resulting in a yield strength (YS) of 178 MPa, an ultimate tensile strength (UTS) of 310 MPa, and an elongation (El) of 9%. After BH treatment, the GPII zones transformed into semi-coherent T′-Mg₃₂(AlZnCu)₄₉ precipitates (~2.4 nm), which strengthened the alloy through their semi-coherent interfaces. The retained GPII zones mitigated the loss of ductility, and the final mechanical properties reached a YS of 275 MPa, a UTS of 340 MPa, and an El of 8.5%, corresponding to a BH response of 97 MPa. Strengthening-mechanism calculations indicated that GP zones contributed approximately 120 MPa to the yield strength in the T4P state, whereas T′ precipitates contributed about 169.64 MPa after BH treatment. The calculated values agreed well with the experimental results, with a deviation of less than 3%. This study clarifies the precipitation sequence in the alloy—supersaturated solid solution → GPI zones → GPII zones → T′ phase—and establishes the relationship between microstructure and strength–ductility behavior. The findings provide theoretical guidance for the design and optimization of high-strength, high-formability aluminum alloys for automotive outer-panel applications. Full article

The repair of large segmental bone defects remains a major clinical challenge. Traditional bone repair materials often suffer from mismatched degradation rates, insufficient mechanical strength, or limited bioactivity. Biodegradable zinc alloys have emerged as potential alternatives due to their suitable degradation rate and good biocompatibility, though their bioactivity requires further enhancement. In this study, a zinc phosphate (ZnP) coating was applied on the surface of zinc–copper (Zn–Cu) alloy via a phosphate chemical conversion method, and the corrosion resistance, wear resistance, and osteogenic properties of the coating were systematically evaluated. Results showed that the ZnP coating prepared at pH = 2.5 exhibited a dense structure and high crystallinity, reducing the corrosion rate to 0.010 μm/year and increasing the ultimate tensile strength to 117.03 ± 0.78 MPa, significantly improving the wear and corrosion resistance of the alloy. In vivo experiments demonstrated that the material markedly promoted new bone formation and osseointegration. Micro-computed tomography (Micro-CT) revealed that key indicators such as bone volume fraction (approximately 50.26%) and trabecular number (approximately 161.31/mm³) were superior to those of the β-tricalcium phosphate (β-TCP) group and the control group. Histological analysis confirmed its excellent osteogenic activity and mineralization capacity. Biosafety assessments indicated no systemic toxic reactions. The ZnP-coated Zn-1Cu alloy showed promising application in treatment of bone defect. Full article

This research focuses on the investigation of microstructure, deformation, and superplastic behavior in wide range of strain rates of novel crossover Al-Zn-Mg-Cu alloy with Y/Er. The precipitation and superplastic behavior of the Al-Zn-Mg-Cu-Zr-Cr-Ti with Er/Y and Fe/Si impurities alloys have been studied. The microstructure of the alloys with nano-sized precipitates and micron-sized particles allows obtaining a micrograin stable microstructure. The spherical D0₂₃-Al₃(Er,Zr) precipitates with a diameter of about 20 nm and rod-like crystalline and qusicrystalline E (Al₁₈Mg₃Cr₂) precipitates with a thickness of about 20 nm and length of about 150–200 nm were identified by transmission electron microscopy. The superplastic deformation behaviors were investigated under different temperatures of 460–520 °C and different strain rates of 3 × 10⁻⁴ to 3 × 10⁻³ s⁻¹. The microstructure observation shows that uniform and equiaxed grains can be obtained by dynamic recrystallization before superplastic deformation. The alloy with Y exhibits inferior superplastic properties, while the alloy with Er has an elongation of more than 350% at a rate of 1 × 10⁻³ s⁻¹ and a temperature of 510 °C. Full article

By tuning the extrusion parameters, the corrosion performances of as-extruded Mg-0.5Zn(-0.2X) alloys (X: Ca/Sr/Ag/In/Cu, denoted as Z05, Z0502-Ca, Z0502-Sr, Z0502-Ag, Z0502-In and Z0502-Cu, respectively) with similar grain sizes were investigated and compared with their as-cast counterparts. The formed Fe-Si precipitates after hot processing significantly accelerate the corrosion rates of Z05, Z0502-Ag and Z0502-In, whereas the driving force from the Fe-encapsulated MgCaSi(Fe) and MgSrSi(Fe) precipitates are not as strong in Z0502-Ca and Z0502-Sr. Impacts from Fe impurity in Z0502-Cu are masked in the fast corrosion due to the noble Mg2Cu intermetallics. Fe precipitation during hot processing is critical for micro-alloyed systems, as the changes in intermetallic/impurity distributions impact the corrosion performances profoundly. The enthalpy of formation and the potential difference are the key factors that influence the distribution of precipitate during hot processing. Full article

The addition of reinforcement particles can considerably improve the mechanical properties of 7xxx series aluminum alloy. In this work, the effects of TiB₂ reinforcement particles on the microstructure, mechanical properties, strengthening mechanisms, and aging precipitation of TiB₂/Al-Zn-Mg-Cu composites were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile testing machine. The results indicate that when the TiB₂ content is 1 wt.%, the composite achieves a tensile strength of 831 MPa while maintaining an elongation of 6.7%, meeting the research objectives of this experiment. When the aging heat treatment temperature is set at 120 °C, the peak aging time is shortened to 20 h. The interfacial phase composed of solute elements preferentially nucleates near the TiB₂ particles during the cooling process. With the increase in TiB₂ content, clustering in localized regions slows down the diffusion rate of interfacial phases into the matrix, thereby increasing the required duration of the solution treatment. Excellent interfacial relationships exist between TiB₂ particles and both the aluminum matrix and the MgZn₂ phase. It is also found that with the increase in TiB₂ content, the aging-hardness response of TiB₂/Al-Zn-Mg-Cu composites is accelerated and the work hardening rate is reduced. In addition, a multi-component strengthening model for the yield strength of the composite was established based on various strengthening mechanisms, including second-phase strengthening, dislocation strengthening, age-precipitation strengthening, and fine-grain strengthening. The results indicate that age-precipitation strengthening and dislocation strengthening are the most significant contributors to strength in the composite. Full article

The mechanical deterioration of Mg alloys during degradation significantly impairs their service performance as biomaterial implants. In the present study, the degradation behavior of a Mg-6Zn-0.5Cu alloy was systematically examined through electrochemical measurements and immersion tests, while the mechanical integrity was assessed via tensile tests under different immersion periods. The results revealed a severe loss in mechanical properties was disproportionate to the corrosion rate. After 7 days’ immersion, the ultimate tensile strength (UTS) and elongation to failure (EL) decreased by 34.4% and 60.1%, respectively, while the corrosion rate was 0.11 mm/y based on the weight loss. This severe mechanical deterioration was primarily caused by pronounced localized corrosion, which induced aggravated local stress concentration at corrosion sites, promoting microcracks initiation and leading to premature fracture of the alloy. Full article

The creation of novel, effective materials with specific properties is necessary to advance technology. To do this, objective regularities between the material’s composition, structure, and properties must be found. A comparative analysis of glass-forming regions, arranged according to the systematic substitution of one element by its analog within a periodic system subgroup, provides a useful framework for discussing trends in glass formation in semiconductor alloys. In this review, the information on the glass formation in the chalcogenide systems GeSe₂–As₂Se₃–MeCh, where Me = Cu, Ag, Zn, Cd, Sn, Pb; Ch = Se, Te, was subjected to a thorough comparative analysis to establish objective patterns in the change in the glass-forming ability in these systems. The effect of MeCh on the formation of glass in the binary system GeSe₂–As₂Se₃ was traced. Full article

Liquid metal embrittlement (LME) occurs when a normally ductile alloy undergoes brittle fracture in contact with a liquid metal. The mechanisms behind LME remain unclear, and most of the models rely on post mortem analyses. In this work, we overcome this limitation by performing in situ scanning electron microscopy (SEM) notched micro-bending tests on α-brasses exposed to the gallium–indium eutectic (EGaIn) at room temperature, enabling real-time correlation between load–displacement curves and crack evolution during LME. In the Cu-30%Zn alloy, LME was observed only after prior plastic deformation and ductile crack growth, confirming that liquid metal did not influence early plasticity. A two-step experiment further showed that a pre-existing crack in contact with EGaIn, under continued loading, was sufficient to trigger brittle fracture. The Cu-20%Zn alloy displayed alternating ductile and brittle events, with brittle cracks propagating horizontally before arresting in undeformed zones, leading to stepped load–displacement curves. By contrast, pure Cu and Cu-15%Zn showed only ductile fracture despite continuous contact with EGaIn. These results demonstrate that LME in the Cu-Zn/EGaIn system acts during crack propagation rather than initiation. The present in situ SEM methodology provides direct evidence of fracture mechanisms and a framework for future experimental modeling comparisons. Full article