Solution Treatment Research Articles

Comparison of Total Bacterial Count in Contact Lenses with Different Treatments of Contact Lens Solutions

The use of contact lenses continues to increase, raising attention to aspects of eye health because of their hygienic factors. The hygiene of contact lenses comes not only from the way they are treated but also from the soaking fluid. This study aimed to determine the total bacterial count on contact lenses with and without the use of immersion solutions. The research method used is a comparative descriptive research method that compares the two pairs of contact lenses with two different contact lens solutions. The total bacterial count was calculated using the total plate count (TPC) method. The number of bacterial colonies for contact lenses before being immersed in liquid A was found in dilution 10-2 with an amount of 4.4×103 CFU/mL, and after soaking, it was in dilution 10-1 with an amount of 8.5×102 CFU/mL. The number of bacterial colonies on contact lenses before being immersed in B liquid was found in 10-1 dilution with an amount of 1.3×103 CFU/mL, and after being soaked, the average colony was 3.9×104 CFU/mL. From these results, it can be seen that in contact lenses and liquid A, there is a decrease in the number of bacterial colonies, while on the other hand, in liquid B, there is an increase in the number of bacterial colonies. The causal factor is thought to originate from the composition of the solutions. However, do not rule out contamination from bottles and contact lens care. Therefore, this research can be used as a basis for hygiene education in contact lenses.

Orientation Influence on Tensile Strain Hardening in Forged Plates of AA2014 Aluminium Alloy

Strain hardening is an effective strengthening method for alloys that requires plastic deformation of the material during manufacturing. The strength will significantly increase due to the number of dislocations formed during plastic flow of material. This study examines the plastic flow activity of forged plates of an AA2014 aluminium alloy with tensile test conditions. The effects of solution treatment and artificial ageing on strain hardening characteristics and tensile behaviour were investigated using tensile testing and scanning electron microscopy. Hollomon plastic flow relationship was employed for solution treated and age hardening conditions by experimental engineering stress- engineering strain data of the aluminium alloy AA2014. In both solution-treated and age-hardened conditions, the alloy displays three distinct strain hardening rate levels. The highest rate of strain hardening occurs both in solution-treated and age hardening conditions in regions with lower strain. It is also noted that specimens experience higher and lower strain hardening rates in the forging direction (Longitudinal, L) and perpendicular to the forging direction (Transverse, T) respectively in both solution-treated and age hardening conditions. In order to bring out the degree of in-plane anisotropy, test are conducted in L, L+45° (45° to L direction) and T in the plane of forging. Lower and higher magnification SEM images of the alloy under study, clearly exhibited that the ductile dimple fracture associated with a lower shear fracture contributions.

The effect of anodization and subsequent treatments on corrosion resistance of aluminium

Aluminium samples were chemically prepared by following operations: degreasing, etching I, etching II, and brightening), prior to anodizing in sulfuric acid. Aluminium surface area was 0.2 dm2. The composition of used aluminium samples was determined by the energy dispersive X-ray spectroscopy. Chemically prepared aluminium samples were electrochemically anodized for 45 minutes in a solution of 190 gdm-3 H2SO4 at room temperature, at a current density of 1.7 Adm-2. In the anodizing process, the aluminium sample served as the anode, with lead cathodes. After anodizing, the aluminium samples underwent a colouring process in five pairs of solutions (systems), where each system consisted of two solutions of inorganic salts RxA + RxB (x = 1-5, numbers of solutions). Colouring of the anodized aluminium was carried out at room temperature by immersing the samples in each solution for 7 minutes (e.g., R1A + R1B, τ = 7 min + 7 min). Each used colouring system provides a different colour: green-yellow, brown, light-grey, blue, and orange-gold. After colouring, the samples were treated in a special solution to improve corrosion resistance and silication, resulting in a change in the obtained colour shade. All obtained colours were stable with very nice appearance, allowing such coloured aluminium to be used for decorative purposes. The corrosion resistance of the coloured anodized aluminium samples was investigated by determining the corrosion potential, corrosion current and polarization resistance using potentiodynamic polarization method, as well as by electrochemical impedance spectroscopy. A common feature of all tested samples is a significant improvement in the corrosion resistance of the anodized aluminium after colouring and subsequent treatment in the corrosion resistance improvement solution, particularly after the additional silane treatment.

Cryo-Rolled AA5052 Alloy: Insights into Mechanical Properties, Formability, and Microstructure

Industries operating in extreme conditions demand materials with exceptional strength, fatigue resistance, corrosion resistance, and formability. While AA5052 alloy is widely used in such industries due to its high fatigue strength and corrosion resistance, its strength frequently falls short of stringent standards. For AA5052 alloy, this study explores the combined use of solutionizing and cryo-rolling, followed by annealing, to improve strength. Although several alloys have been reported to undergo solution treatment before cryo-rolling, this study focuses on how post-processing via annealing can lessen the formability constraints usually connected to conventional cryo-rolling. The study sheds light on the ways that solutionizing, cryo-rolling, and annealing interact to affect the alloy’s mechanical characteristics. Microstructure analysis shows that solutionizing improves the grain structure by reducing dynamic recovery, promoting dislocation density, and facilitating precipitate formation. Sheets subjected to solutionizing + cryo-rolling and partially annealed at 250 °C produce optimal results. Interestingly, formability is decreased when cryo-rolling alone is used instead of cold rolling, whereas formability is successfully increased when solutionizing is used. Comparing solutionized + cryo-rolled sheets that are partially annealed at 250 °C to cold-rolled sheets that are annealed at the same temperature, the former show notable quantitative improvements: a notable 17% increase in ultimate strength, a 10% boost in yield strength, and a noteworthy 13% enhancement in microhardness. Formability has improved with the solutionized + cryo-rolled specimens by annealing. This proposed approach led to noticeable gains in formability, hardness, and strength, which would significantly improve material performance for industrial applications.

A Study on the Treatment of Sodium Sulfate Waste Solution by Constant Current Control Bipolar Membrane Electrodialysis

As environmental pollution has intensified, the importance of recycling spent lithium-ion batteries (LIBs) has significantly increased. Valuable metals contained in LIBs are typically recovered through processes such as leaching, precipitation, and solvent extraction. However, these recycling processes require large amounts of sulfuric acid and caustic soda, resulting in the generation of significant volumes of Na<sub>2</sub>SO<sub>4</sub> waste solution. In order to solve this problem, recent research has focused on using bipolar membrane electrodialysis (BMED) technology to split Na<sub>2</sub>SO<sub>4</sub> and simultaneously recover H<sub>2</sub>SO<sub>4</sub> and NaOH. This study investigated the process of recovering H<sub>2</sub>SO<sub>4</sub> and NaOH from Na<sub>2</sub>SO<sub>4</sub> solution using BMED in a threecompartment cell under constant current conditions. The study evaluated the effects of current density, initial Na<sub>2</sub>SO<sub>4</sub> concentration, and initial H<sub>2</sub>SO<sub>4</sub> and NaOH concentrations. Recovery of H<sub>2</sub>SO<sub>4</sub> and NaOH, current efficiency, energy consumption, and process time were analyzed to determine optimal conditions. Under optimal conditions (1.30 M Na<sub>2</sub>SO<sub>4</sub> solution at 360 A/m²), the recovery of H<sub>2</sub>SO<sub>4</sub> and NaOH were 77.35% and 75.18%, respectively. Energy consumption was 1.43 kWh/kg, with current efficiencies for the acid and base of 51.1% and 49.7%, respectively.

Surface Roughening Behavior and Mechanism in Aluminum Alloy Under Tensile Deformation.

Surface roughening (SR) has been found to occur in solid solution 2219 aluminum alloy under tensile deformation, which will deteriorate its surface quality. To make a precise study of the surface roughening (SR) behavior and mechanism, the surface morphology of annealed and solid solution 2219 aluminum alloy was compared and crystal plasticity finite element (CPFE) simulation was carried out in this study. Thereinto, representative volume element (RVE) models of polycrystals were established according to the initial grain morphology measured by electron backscatter diffraction (EBSD). The results show that the surface roughening degree of the solid solution specimen is worse than that of annealed specimen after uniaxial tension deformation. In comparison with the annealed specimen, the grains show a larger size after solid solution treatment, thus resulting in the coarse surface to a certain extent. Moreover, texture type and density also have a significant influence on surface roughness. The rotation of grains with an S and Copper orientation intensifies the surface roughening during tensile deformation. The deformation difficulty of Goss texture in the normal direction (ND) and tangential direction (TD) varies, thus contributing to the different surface morphology. The research results will provide guidance for the improvement of the surface quality of high-strength aluminum alloy aerospace components.

Mineral nutrition for Cannabis sativa in the vegetative stage using response surface analysis.

Cannabis cultivated for medical and adult use is a high-value horticultural crop in North America; however, we lack information on its optimal mineral nutrition due to previous legal restrictions. This study evaluated the mineral requirements of nitrogen (N), phosphorus (P), and potassium (K) for cannabis in the vegetative stage using response surface analysis. Plants were cultivated in a hydroponic system with various nutrient solution treatments (mg L-1) of N (132.7, 160, 200, 240, and 267.3), P (9.6, 30, 60, 90, and 110.5), and K (20.8, 60, 117.5, 175, and 214.2) according to a central composite design. Nutrient interactions (N × K, K × P, and N × P × K) had a significant effect on the vegetative growth of the cannabis plants. N × K interaction had a significant effect on leaf mass and stem mass. K × P interaction had a significant effect on dry root mass, leaf mass, stem mass, leaf area, specific leaf area, and chlorophyll a and b contents. N × P × K interaction had a significant effect on root mass, leaf mass, stem mass, stem diameter, leaf area, and chlorophyll a and b contents. The optimum concentrations of total nitrogen, P, K, calcium, and sulfur in the cannabis leaves were 0.54, 0.073, 0.27, 0.56, and 0.38 mg g-1, respectively. An increase in P and K concentrations decreased the magnesium concentration in the leaves, but it was unaffected by the increase in N concentration. The recommended primary macronutrients for cannabis plants in the vegetative stage based on the maximum desirability and nutrient use efficiencies were 160-200 mg L-1 N, 30 mg L-1 P, and 60 mg L-1 K. These findings can offer valuable insight and guidance to growers regarding the mineral requirements for cannabis during the vegetative stage.

Editorial

Homeopathy, once considered solely a well-established alternative or complementary healing discipline, has also become a focal point for a burgeoning branch of scientific exploration. Beyond its conventional healing practice, the foundations and mechanisms of potentized high dilutions are subject to scrutiny through an expanding body of scientific research. These investigations go far beyond clinical studies and include tissue and cellular models of different organisms and, more recently, ecology. In addition, in the last decades, the stated research has gone far beyond living beings since it extended to the physicochemical realm, studying the altered characteristics of fluids subjected to the homeopathic ultra-high dilution (UHD) process. Extensive scientific efforts have offered convincing evidence of the altered properties of fluids treated with the UHD methodology. These findings provide substantial support for the view that the efficacy of homeopathy is rooted in the emergent properties of polar solvents, water, in particular. More than that, the water properties we learn about from UHD solutions also occur in other treatments of water or aqueous solutions. This is why we can establish a new science of emergent properties of water. It is to substantiate and make new steps in developing this science that the November Conference in Ljubljana was dedicated to. This multi-faceted approach sheds light on the fundamental principles of the effectiveness of homeopathy as well as of many other non-chemical water treatments, opening up an entirely new horizon for the development of global health, ranging from individual living beings, including humans, through ecosystems to planet Earth as a whole. The XXXVII GIRI Meeting was held in November 9-12th, 2024 in Ljubljana, at the Town Hall, Slovenia, with the co-participation and shared organization of Bion Institute, Ljubljana, Slovenia, and World Water Lab consortium, an initiative to gather scientists interested to understand and advance the science of emergent properties of water. Research into water is different from the investigation of other substances because it so aptly reflects some as yet hidden principles and laws of nature. Many of them show to be utterly neglected or even banned from the standpoint of conventional (academic) sciences since they do not conform to their mechanistic and reductionist models. These profound features are investigated by water scientists working on all aspects of water properties, from physicochemical and biological aspects to the quantum electrodynamic field view. The initiative to gather these three institutions (GIRI – BION – WWL) allowed to discuss together and create a wide view of UHD effects on living systems. The program was organized in four Keynote talks, two round tables and 15 individual presentations selected from a careful peer-review process. One general seminar about the main topics studied in the context of the WWL activities closed the meeting. All talks focused the physicochemical aspects of UHDs, mainly the probable field effect, provoking a discussion about how good-quality basic research can improve the plausibility of clinical / agronomic use of UHD preparations, which seems to be an essential grounding for the evidence-based medicine clinical studies (including the veterinary ones) by improving its trial protocols, and for a high-tech sustainable resource of food production. Since both aspects are complementary, the need of high-level clinical studies on homeopathy and high dilutions is an urgent issue as well, as was also discussed. At the end of the conference, the Madeleine Bastide Prize was given to the best individual presentations, being the first place attributed to Prof. Fateme Mirzajani (Iran), the second place to Dr. Leonardo Faedo (Brazil - UK), and three mentions were given to Sandra Tribolo (France), Lorena Guimarães (Brazil), and Adriana Miranda (Brazil). We wish the readers an enjoyable read!

Hot Bending–Quenching Characteristics of Heat Treatable A6063 Aluminum Tubes

This study investigates the application of hot bending–quenching technology to heat-treatable A6063 aluminum tubes, focusing on the bending formability and mechanical properties after aging treatment under various heating conditions. High-frequency induction heating was used to uniformly heat aluminum tubes to the solution treatment temperature of 560 °C. The effect of wall thickness on bending formability was explored, revealing that thinner tubes (2 mm) experienced significant flattening defects, whereas thicker tubes (5 mm) exhibited superior formability with reduced shrinkage and wall thinning. Additionally, the pre-quenching temperature was found to influence the mechanical properties of the tube with a thickness of 5 mm. Tubes held at the solution temperature for 1 min 30 s or longer maintained higher temperatures during transfer, resulting in improved tensile strength and hardness after aging. The findings confirm the feasibility of applying hot bending–quenching technology to aluminum tubes, though careful control of temperature loss during continuous industrial processes is required to ensure optimal mechanical performance.

Microstructure and mechanical properties of Mg-Gd-Zn-Zr alloy after hot extrusion

The microstructural evolution and mechanical properties of the Mg-6Gd-1Zn-0.5Zr (wt.%) alloy during heat treatment and composite extrusion were studied in this work. The (Mg, Zn)3Gd phase and a small amount of 14H long-period stacking ordered (LPSO) phase formed in the cast alloy, and more lamellar 14H-LPSO phases formed in the alloy during homogenization treatment. The bimodal grain structure composed of coarse deformed microstructure and fine dynamic recrystallization (DRX) grains formed in the alloy after extrusion. The γ′ phase and β´ phase precipitated after the extrusion process and after the solution and aging treatment, respectively. The kinking of the lamellar 14H-LPSO phase occurred during the extrusion process. DRX grains formed in the alloy during extrusion process through continuous dynamic recrystallization (CDRX), particle stimulated nucleation (PSN), and kinking-assisted DRX. The yield strength, tensile strength and elongation of the extruded alloy were 227MPa, 320MPa, and 20.68%, respectively. The strength and elongation of the extruded alloy are enhanced by the strengthening effect from the bimodal structure, kinking of the LPSO phase, and LPSO phase. The tensile properties of the alloy decreased after the solution and aging treatment. The bimodal structure and kinking of the LPSO phase disappeared after the solution and aging treatment.

Treatment of liquid fertilizer solutions by electrohydraulic effect and assessment of increasing the efficiency of plant nutrition

Abstract The article discusses the issue of increasing the efficiency of plant nutrition by treating liquid organic and mineral fertilizers with an electro-hydraulic effect. The amount of nitrates in water is reduced to 1.1 mg/l due to electro-hydraulic treatment. This creates the possibility of feeding plants and at the same time eliminating E. coli bacteria in liquid fertilizers from 2.23 mg/l. up to 102.7%, i.e. 82.55% compared to the control in exchange for its neutralization, which can prevent it from passing through the plant into the human and animal body, resulting in human health being maintained. As a result of the research, a process for electrohydraulic processing of liquid fertilizers was established, where the following processing modes and parameters were established to ensure the degree of grinding of solid particles in the liquid, processing voltage: U = 24 kV, capacitor capacity: C = 0.8 μF., number of pulses: n=175 pulses, which turned out to be sufficient. Due to electro-hydraulic processing the rate of fertilizer uptake by plants has been improved over existing technology by optimizing the breakdown of coarse fertilizers into liquid solution through electro-hydraulic treatment of liquid fertilizer solutions. As a result, it was possible to increase the yield to 33 g for tomatoes and 37 g for cucumbers per 1 hectare owned by the farm using the method of electro-hydraulic treatment of liquid fertilizers.

A quasi-in-situ EBSD study on the effect of abnormal grain growth on mechanical properties of the friction-stir welds of 2219 aluminum alloy

Abnormal grain growth appears in the friction stir welds of 2219 aluminum alloy during solution treatment. In this study, the effect of abnormal grain growth on the mechanical properties of the friction-stir welds of 2219 aluminum alloy was investigated, combined with the quasi-in-situ EBSD experiment. The results show that the solution-treated welds with coarse grains have lower tensile strength and elongation than the base metal, but the fracture mode remains the same. According to the bulging testing results, the limiting dome height and ultimate bulging rate of the solution-treated tailor-welded blanks are 85% and 77% of the base metal, respectively. After T6 treatment, the mechanical properties of the weld with coarse grains, especially the elongation after fracture, further decrease compared to the base metal. The stress concentration caused by abnormal grains is the main reason for the decreased mechanical properties of the solution-treated weld. There are copper-poor zones along the grain boundaries because of the rapid precipitation at grain boundaries during T6 treatment. Therefore, abnormal grain growth makes intergranular cracks easier to initiate and propagate, which results in the decrease of elongation of the T6-treated weld.

Development and Characterization of an Environmentally Friendly Soy Protein-Modified Phenol–Formaldehyde Resin for Plywood Manufacturing

Most wood-based panels were currently prepared using aldehyde-based adhesives, making the development of natural, renewable, and eco-friendly biomass-based adhesives a prominent area of research. Herein, the phenolic resin was modified using a soybean protein isolate (SPI) treated with a NaOH/urea solution through a copolymerization method. The physicochemical properties, chemical structure, bonding properties, and thermal properties of the soybean protein-modified phenolic resin (SPF-U) were analyzed using Fourier transform infrared spectroscopy, thermogravimetric analysis, and formaldehyde emission tests. The results indicated that the molecular structure of the soy protein isolate degraded after NaOH/urea solution treatment, while the gel time was gradually shortened with increasing NaOH/urea solution-treated soy protein isolate (SPI-U) dosages. Although the thermal stability of the soy protein isolate was lower than that of the phenolic resin, the 20% SPF-U resin demonstrated better thermal stability than other modified resins. The PF modified with 30% SPI-U (SPF-U-3) exhibited the lowest curing peak temperature of 139.69 °C than that of the control PF resin. In addition, all modified PF resins exhibited formaldehyde emissions ranging from 0.18 to 0.38 mg/L when the SPI-U dosage varied between 20% and 50%, thereby meeting the E0 plywood grade standard (≤0.5 mg/L).

Effect of solution aging treatment on corrosion resistance and erosion resistance of laser metal deposition 17-4PHss

Slurry erosion and cavitation erosion are the primary causes of failure in pass flow components, and preventive maintenance can effectively extend their service life. In this paper, 17-4PH stainless steel was prepared using laser metal deposition (LMD) technology and aged to investigate the effect of solution treatment on its microstructural transformations. The microhardness, electrochemical corrosion behavior, slurry erosion resistance, and cavitation erosion behavior of the as-built and solution-treated, aged samples were analyzed, with traditional forged specimens used as controls. During heat treatment, the microstructure fully transformed to martensite, and NbC precipitated as a second phase. Solution treatment led to microstructural coarsening, while aging significantly refined the microstructure and produced partial reverted austenite. Microhardness analysis showed that the microhardness of the solution-treated and aged samples increased to 465.5 ± 8.6 HV0.2 due to the combined effects of finer and more uniformly distributed NbC precipitation and grain refinement. The solution aging samples exhibited the lowest corrosion current density and the highest corrosion potential, influenced by the presence of reverted austenite. Slurry erosion results indicated that the corrosive environment accelerated mass loss due to the synergistic effects of mechanical abrasion from gravel and brine corrosion. Meanwhile, the solution aging samples demonstrated superior resistance to slurry erosion, with mass losses in clear water and brine slurry of only 69 % and 63 % of those observed in the traditional forged samples. In the cavitation erosion experiment, the solution aging sample showed the lowest cumulative mass loss (3.54 ± 0.18 mg), and the work-hardening of the reverted austenite further enhanced the cavitation erosion resistance of the solution aging sample.

Microstructures and mechanical properties of a novel Al-5Mg-3Zn alloy with the combined additions Sc and Zr

The study investigated the impact of Sc and co-addition of Sc and Zr on the dispersoids, subsequent grain structures and aging precipitations, and the ultimate mechanical properties of Al-5Mg-3Zn-xSc-yZr (x + y = 0.2wt.%) alloys were studied. The results indicate that the co-addition of Sc and Zr produces the highest number density of dispersoids among the three alloys. The Al-5Mg-3Zn alloy mainly comprises fully recrystallized equiaxial grains (close to 100%) after solution treatment. In contrast, the recrystallization ratio of Al-5Mg-3Zn-0.1Sc-0.1Zr remarkably decreases to 9% owing to the presence of fine and dense Al3M dispersoids to impede the mobility of sub-grain boundaries. Adding the Sc element alone reduces the number density of the T-Mg32(Al, Zn)49 and enhances their size during the subsequent aging treatment, while the co-addition of Sc and Zr elements shows an opposite trend. The primary factor contributing to this result is that the microalloying of Sc and co-addition of Sc and Zr affects the diffusion of Mg and Zn solute atoms in Al-5Mg-3Zn alloys. Consequently, the peak-aged Al-5Mg-3Zn-0.1Sc-0.1Zr alloys exhibit a yield strength of 481MPa, an ultimate tensile strength of 547MPa, and an elongation of 12%, which is superior to the reported Al-5Mg-3Zn alloys. The good strength-ductility synergy can be attributed to the combination of a high number density of dispersions, grain refinement, and high-volume fraction nanoprecipitates.

Phosphoramidate functionalization of hybrid chitosan/SiO2 beads for efficient sorption of ruthenium and application on seawater as a case study

Ruthenium removal from complex solutions (highly saline effluents, seawater) is a critical challenge. Herein, the sorption capacity of chitosan/SiO2 composite beads (Ch-Si) for ruthenium nitrosyl is increased three-fold after phosphoramidate grafting (DPA-Ch-Si, 1.6 mmol Ru g−1) at pH 5. Uptake kinetics and sorption isotherms are compared at pH0: 3, 5 and 10; playing with the mode of agitation (mechanical, MA, vs. ultrasonic treatment, UT). The sorbent maintains good sorption capacities at pH 3 and 10. Uptake kinetics modeled by pseudo-first order rate equation is boosted by functionalization. For Ch-Si, sorption isotherms are modeled by the Langmuir or Sips equations (depending on the pH), while for DPA-Ch-Si the best fits depend on pH, temperature and mode of agitation. Ruthenium sorption is spontaneous and endothermic for the two sorbents. For DPA-Ch-Si, the sorption capacity increases from 1.62 to 1.70 mmol Ru g−1 to 2.23–2.32 mmol Ru g−1 (T increasing from 21 to 50 °C). Nitric acid solution (0.3 M) reveals highly efficient for back extraction; ruthenium is completely released in <15 min. The functionalized sorbent can be reused for a minimum of 10 cycles, with limited loss in performance. Phosphoramidation improves sorption selectivity for the treatment of equimolar multicomponent solutions (Na, Ca, Mg, Fe, Al, U, and Nd). The effect of pH on sorption selectivity is evaluated in simple multi-metal solutions and complex environment. In seawater, the selective recovery of ruthenium is favored at pH close to 10. These tests confirm the promising perspectives offered for ruthenium removal from complex environments. Physicochemical characterizations of the sorbent (and their modes of interaction with ruthenium nitrosyl) included SEM, BET, TGA, FTIR, XPS, and elemental analyses.

Effect of heat treatment on microstructure and mechanical properties of WE43 alloy fabricated by wire arc additive manufacturing

Heat treatment is an effective method to improve the mechanical properties of Wire Arc Additive Manufacturing (WAAM) WE43 alloy. This study investigates the effects of heat treatment on the microstructure and mechanical properties of the WE43 alloy processed by WAAM. The as-deposited samples exhibit a uniform equiaxed crystal structure, with grain size gradually increasing as the number of deposited layers grows. The as-deposited microstructure comprises eutectics and a small amount of cubic phases, and the phase content escalates as the amount of deposited layers increases, influenced by the cumulative effect of multiple thermal cycles. At lower solid solution temperatures (480 ℃ × 8h), most of the eutectic phase remains undissolved. During tensile testing, undissolved eutectics tend to cause stress concentrations, leading to cracks that result in sample fractures, negatively affecting the mechanical properties. At higher solid solution temperatures (520 ℃ × 8h), most of the eutectic dissolves, but abnormal grain coarsening (AGC) in the interlayer fine-grain region occurs, causing a significant reduction in the sample's mechanical properties. After solid solution treatment at 500 °C for 8hours, only a small amount of eutectics remains undissolved, and the AGC phenomenon is not observed, resulting in an optimal solid solution effect. Subsequently, after aging treatment at 225 °C for 18hours, dense nanoscale β′′ phases precipitated within the alloy grains, significantly improving the mechanical properties. The samples achieved optimal performance, with UTS, YS, and EL of 323±15.2MPa, 225±11.3MPa, and 8.4±1.1%, respectively.

Achieving an excellent combination of strength and ductility in metastable β titanium alloys via coupling isothermal ω phase and TRIP/TWIP effects

TRIP/TWIP metastable β titanium alloys demonstrate high strain hardening rates and excellent tensile ductility. However, the precipitation of nanometer-sized ω phase through microstructural control significantly improves strength but often results in a significant decrease in ductility. This research proposes a novel strategy by precipitating isothermal ω phase (ωiso) and integrating mechanical twinning/martensitic transformation to address these challenges. The single-phase β coarse-grained (CG) specimens of metastable Ti25Nb (at.%) alloy were subjected to solution treatment in the β phase region, followed by aging at 300 °C for 60 min to obtain CG60. The ωiso-reinforced CG60 specimen exhibited a 12 % uniform elongation (1 % higher than CG specimen) and a yield strength of 857 MPa (approximately 67 % higher than CG specimens). In the CG60 specimen, deformation mechanisms were mainly attributed to the TRIP, TWIP and dislocation slip, with TWIP being predominant. As aging time increased, ω phase (localized barriers) and improved β matrix stability progressively suppressed TRIP and TWIP effects, with TWIP being completely inhibited first. Transmission electron microscopy and computational findings suggest that a denser distribution of ωiso contributes more significantly to the strengthening of the alloy.

Investigation on surface properties of AZ31 magnesium alloy modified by micro-arc oxidation and cathodic deposition techniques

Cathodic deposition (CD) technology, as a surface treatment technology, is widely used to prepare surface protective layers of non-valve metals. However, due to the presence of a dense oxide film on the surface of valve metal, during the CD process, this dense oxide film will hinder the contact between ions in the electrolyte and the substrate surface, making CD deposition technology unsuitable for valve metal. In this paper, valve metal AZ31 Mg alloy was first treated by micro-arc oxidation (MAO) technology, and then CD treatment was performed using ethylene glycol organic solution as electrolyte. This method not only solves the problem that CD technology cannot be applied to valve metals and successfully prepares a coating with excellent friction and corrosion resistance, but also explores a new solution as a CD electrolyte. By comparing with the samples after CD treatment in deionized water solution and the samples after MAO, the results show that after CD treatment in deionized water solution, only the porosity (8.572 %) and coefficient of friction (COF) (0.403) of the coating were improved, but after CD treatment in ethylene glycol solution, the coating surface had the lowest porosity (4.263 %), the highest hardness (265.2 HV), and the smallest COF (0.362). Electrochemical tests further showed that the sample had the lowest corrosion current density (5.6099 × 10−10 A/cm2) after CD treatment in ethylene glycol electrolyte. The coating prepared by this method can be widely used in aerospace, medical equipment and other fields due to their excellent friction and corrosion resistance, and can increase the service life of Mg alloy parts. However, this method is currently more suitable for the processing of small parts. This study not only provides a valuable strategy for improving the performance of MAO coatings, but also provides a new direction for the application of CD technology on valve metals.

Microstructure and mechanical properties at elevated temperatures of as-built and heat-treated Inconel 718 produced through laser powder bed fusion processes

Purpose This study aims to better understand the influence of various post-treatments on the microstructure and mechanical properties of additively manufactured parts for critical applications. Design/methodology/approach In this study, Laser Powder Bed Fusion (LPBF) fabricated Inconel 718 (IN718) samples were subjected to various heat treatments, namely homogenization, solution heat treatment and double aging, to investigate their influence on the microstructure, mechanical properties and fracture mechanism at an elevated temperature of 650 °C. Homogenization treatment was performed at 1080 °C for durations ranging from 1–8 h. The solution treatment temperature varied from 980 °C to 1140 °C for 1 h, followed by double aging treatment. Findings At 650 °C, the as-built sample showed the minimum strength but demonstrated the maximum elongation to failure compared to the heat-treated samples. The strength of the IN718 superalloy increased by 20.26% to 34.81%, while ductility significantly reduced by 65.26% to 72.89% after various heat treatments compared to the as-built state. This change is attributed to the enhancement in grain boundary strength resulting from the pinning effect of the intergranular δ-phase. Originality/value The study observed that the variations in the fracture mechanism of LPBF fabricated IN718 depend on the duration and temperature of heat treatment. This research provides a thorough overview of the high-temperature mechanical properties of LPBF fabricated IN718 subjected to different homogenization times and solution treatment temperatures, correlating these effects to the corresponding changes in microstructure.