Effect of solution treatment and aging on the mechanical properties of Al-Mg-Si-Mn-Sc-Zr alloys fabricated by additive manufacturing

Valorization of jeans waste into activated carbon through thiosulfate activation

This work reveals the precipitation behavior in an Mg-3Al-5Zn-3Ca alloy during isothermal aging (without prior solution treatment) and its effects on mechanical properties and thermal conductivity. Significant precipitation of micro-scale C15-Al 2 Ca Laves phase occurs within the grains only when the temperature reaches 350 °C. During the initial aging stage, the precipitation fraction, number density, and size increase with aging time, while the solute-enriched zones near the grain boundary Ca-containing second phases are gradually consumed by nearby precipitation. Peak aging is achieved after 20 h. Upon further aging to 60 h, the volume fraction and average size of the precipitates continue to increase, exhibiting a balanced combination of properties. Dissolution of the grain boundary phases and precipitates occurred after 100 h.

ABSTRACT Direct Metal Laser Sintering (DMLS) enables the fabrication of complex metallic components with excellent dimensional accuracy and tailored microstructures. This study investigates the effect of heat treatment and laser micro-engraving on the microstructure and biocompatibility of DMLS-processed Inconel 718 alloy. The fabricated specimens were subjected to solution treatment followed by double ageing to promote γ′ and γ″ precipitates. Optical microscopy and scanning electron microscopy revealed that heat treatment transformed the dendritic as-built microstructure into a homogeneous equiaxed structure. Laser micro-engraving produced well-defined surface textures, with the heat-treated alloy exhibiting higher surface roughness and enhanced surface activity. Biocompatibility was evaluated using an MTT assay with L929 fibroblast cells. After 72 h of exposure, the as-built alloy exhibited a cell viability of 79.9%, whereas the heat-treated alloy achieved 84.1%, corresponding to an improvement of approximately 5.3%. Microscopic observations further confirmed improved cell attachment and spreading on the heat-treated surface. The results indicate that heat treatment combined with laser micro-engraving enhances the biological performance of DMLS-processed Inconel 718 for potential biomedical applications.

ABSTRACT Nickel-based superalloys, particularly Inconel 718, are extensively employed in gas turbine blade applications owing to their excellent high-temperature strength and corrosion resistance. However, these alloys remain susceptible to degradation in aggressive marine environments. This study investigates the corrosion behaviour of laser-bed powder fusion processed Inconel 718 subjected to two post-processing heat treatment conditions: solution-treated (ST) and solution-aged (SA). Electrochemical performance was evaluated in 3.5 wt-% NaCl solution using potentiodynamic polarisation and electrochemical impedance spectroscopy. The results revealed that the SA condition exhibited inferior corrosion resistance than the ST condition. The corrosional potential shifted from approximately – 57 mV (ST) to – 129 mV (SA), while the corrosion current density increased from about 3 to 10 μA cm−2, indicating more than three times increase in corrosion after aging. EIS measurements further confirmed the reduced stability in the SA condition through low impedance response. Although passive film formation was observed in both conditions, the SA alloy exhibited a significantly higher density of corrosion pits. Scanning electron microscopy revealed needle-like δ-phase precipitates in the SA condition, which promoted micro-galvanic interactions and enhanced localised pitting corrosion. These findings highlight the critical influence of heat treatment-induced microstructural evolution on the corrosion behaviour of additively manufactured Inconel 718.

Selenium biofortification in soybean is one approach to addressing widespread selenium deficiency in human populations, yet the temporal dynamics of gene expression and antioxidant responses following selenium enrichment remain poorly characterized. Here, we examined the physiological and transcriptional responses of the HK88 soybean variety to selenium-enriched nutrient solution treatment, with seedlings sampled at 1, 24, and 48 h post-treatment. Total tissue selenium rose from 0.01 mg/kg at 1 h to 0.33 mg/kg at 48 h, with parallel increases in both inorganic and organic fractions, consistent with active biotransformation, though this interpretation remains to be confirmed experimentally. Antioxidant responses followed a distinct temporal pattern: superoxide dismutase (SOD) and peroxidase (POD) activities were initially lower in treated plants at 1 h relative to controls but were elevated at 24 and 48 h, while catalase (CAT) activity remained comparatively low across all time points. Malondialdehyde (MDA) levels were lower in selenium-treated plants at 1 h, suggesting early membrane stabilization, though this difference was no longer apparent by 48 h. RNA sequencing of 18 libraries identified 6,793 differentially expressed genes (DEGs) at 1 h, peaking at 13,196 (approximately 18% of the 72,513 annotated genes) at 24 h, then declining to 8,996 at 48 h. A Venn diagram analysis identified 565 DEGs shared across all three time points, comprising 196 consistently up-regulated and 369 consistently down-regulated genes. Up-regulated genes were enriched for nucleotide transmembrane transport functions, including ATP, ADP, and purine transport, with associated ABC transporter activity. Down-regulated genes were predominantly associated with primary carbon metabolism, including monosaccharide biosynthesis, gluconeogenesis, and the Calvin cycle. Gene Set Variation Analysis (GSVA) indicated positive enrichment scores for nucleotide transport pathways at 24 and 48 h in treated plants, contrasting with negative scores in controls. Mantel tests revealed significant associations between gene set activity profiles and measured physiological traits, particularly for gene sets related to molecular function and selenium accumulation. These findings suggest that selenium biofortification in HK88 is associated with a coordinated metabolic shift, in which primary carbon fixation is reduced while nucleotide transport capacity is enhanced, supporting antioxidant defense during selenium assimilation.

Salinity, which hampers wheat growth and development, is one of the major abiotic stresses. Plant-derived smoke (PDS) solution alleviates salt stress and promotes wheat growth and development; however, the underlying molecular mechanisms have not been completely clarified. In this study, nuclear proteomics was employed to reveal the promotive effect of PDS solution on salt-stressed wheat. Nuclear fractions were isolated from wheat roots, and their purity was confirmed via enrichment of histone H3 and reduction of cytosolic ascorbate peroxidase. Using this nuclear purification technique, label-free nano LC-MS/MS-based nuclear proteomics was performed to identify differentially abundant nuclear proteins in salt-stressed wheat with or without PDS solution treatment. Salt stress decreased histone H2A and DNA polymerase levels, whereas PDS solution treatment of salt-stressed wheat increased levels of histone variants (H2A, H2B, H3, and H4), DNA polymerase, and DNA topoisomerase II. In addition, the PDS solution increased the levels of pre-mRNA cleavage factor Im 25 kDa subunit and RNA helicase in salt-stressed wheat. Immunoblot analysis further validated the increase in histone deacetylase levels triggered by the PDS solution treatment in the salt-stressed wheat. These results suggest that PDS solution alters nuclear proteins in a way that contributes to chromatin remodeling and transcription during salt stress.

17-4PH stainless steel is widely used in hydraulic components exposed to cavitation, yet its cavitation erosion resistance (CER) depends strongly on both the manufacturing route and the applied post-processing. This study compares the CER of conventionally processed and DMLS-fabricated 17-4PH steel after solution treatment, precipitation hardening, and shot peening with glass, ceramic, and steel media. The novelty of the work lies in the systematic comparison of these post-processing routes across both manufacturing methods, supported by a structure-property analysis of hardness, surface morphology, phase composition, crystallite size, and microstrain-derived estimated stress magnitude. The DMLS material showed consistently higher CER than the conventional steel. The best performance was observed for the precipitation-hardened and ceramic-shot-peened DMLS specimen, which exhibited an erosion rate of 1.49µm h-1, compared with 4.71µm h-1 for the untreated conventional specimen, representing an improvement of approximately 216%. The superior cavitation performance of the DMLS material was associated with broader retention of the α/γ microstructure after post-processing, indicating that CER is governed not only by hardness, but also by phase constitution and the condition of the near-surface layer.

Restricted by the fragile and unstable intrinsic interface layer, the sodium metal anode (SMA) struggles to withstand volume expansion, dendrites growth, and excessive electrolyte consumption during cycling, which severely hinders the practical development of sodium metal batteries. Herein, a novel biphasic interface layer consisting of Na15Sn4 and NaI is in situ constructed on the SMA surface (Na15Sn4/NaI-Na) via a simple solution treatment strategy. NaI provides efficient ion transport channels and effectively suppresses the electron tunneling, while the sodiophilic Na15Sn4 promotes uniform Na nucleation and deposition. With their synergistic effect, the Na15Sn4/NaI biphasic interface layer significantly facilitates the Na+ diffusion kinetics and inhibits the uncontrolled dendrites growth. Besides, the high Young's modulus (13.5GPa) ensures the Na15Sn4/NaI-Na anode possesses sufficient mechanical strength to avoid stress damage during volume fluctuations. Consequently, the Na15Sn4/NaI-Na-based symmetric cells operate stably for nearly 1000h at 2.0mA cm-2 and 2.0 mAh cm-2 with a low overpotential of 9.5mV. Moreover, the full cells coupled with high-mass-loading Na3V2(PO4)3 cathode (15mg cm-2) retain a high specific capacity of 106.6 mAh g-1 after 150 cycles at 2.0 C. This work provides a scalable approach for developing robust and dendrite-free SMAs.

Overcoming the limitations of conventional solution treatment: synergistic property enhancement of high-alloyed Al-Zn-Mg-Cu alloys via Low-Temperature Pre-Treatment

This study investigates the effect of controlled precipitation hardening on the mechanical behavior of Al6061–fly ash metal matrix composites fabricated using stir casting and subjected to T6 heat treatment. The specimens underwent solution treatment at 510°C for 1 and 2 hours, followed by oil quenching and artificial aging at 120°C, 140°C, and 160°C for 2 hours. Tensile, Rockwell hardness, impact, and fatigue tests were used to assess the mechanical characteristics, in accordance with ASTM standards, and were supported by microstructural and SEM studies. The findings indicate that T6 treatment greatly improves strength and fatigue tolerance compared with the untreated state. The highest tensile strength and impact energy were achieved under the T6-A2 condition (510 °C for 2 h + aging at 120 °C for 2 h), whereas the longest fatigue life was obtained under the T6-B1 condition (510 °C for 1 h + aging at 140 °C for 2 h). This shows a good balance between strength and toughness, which is related to the formation of fine Mg2Si precipitates and enhanced interfacial bonding. Aging at 120°C resulted in the highest hardness at 510°C (2 hours). Over-aging reduced ductility and impact resistance because of precipitate coarsening. For durable aluminum–fly ash composites, these results show a distinct link between processing, microstructure, and material characteristics.

Derivation expansion of the general solubility equation (GSE).

A novel Fe-based alloy, designated as AMSD, was designed using a machine-learning-assisted high-throughput strategy, and it was successfully fabricated by laser powder bed fusion (LPBF) additive manufacturing without crack formation. This work systematically investigated the effects of post-process cooling rates on the microstructure and mechanical performance of the LPBF-fabricated AMSD alloy. After solution treatment at 1200 °C for 2 h, two cooling conditions, namely air cooling (AC) and water quenching (WQ), were applied, followed by aging at 500 °C for 24 h. It was found that the as-built (AB) alloy exhibited a typical cellular structure, epitaxial columnar grains, and a continuous intercellular segregation network. Post-processing eliminated the segregation network and promoted a more homogeneous microstructure with multiscale precipitates. Compared with AC condition, WQ preserved a finer and denser population of grain-boundary borides and achieved a superior strength–ductility balance, with a UTS of 1072 ± 15 MPa and an elongation of 18.2 ± 0.3% achieved. In contrast, the AC sample exhibited a higher UTS of 1436 ± 45 MPa but lower ductility. These results demonstrate that post-process cooling rates play a key role in regulating precipitate evolution and mechanical performance in LPBF Fe-based alloys.

This article presents a new combined post-processing concept to improve the quality of laser powder bed fusion (LPBF) of 17-4PH stainless steel (SS) cylindrical parts fabricated from N2-atomised LaserForm 17-4PH (B) powder. The concept is based on consecutive heat treatment procedures and diamond burnishing (DB) processes. A two-stage study was conducted. The first stage was an LPBF process experiment. The following combination of LPBF parameter values was selected after optimisation: a laser power of , laser scanning speed of v = 1200 mm/s, and layer thickness of . In the second stage, this combination was used to evaluate the effects of two heat treatment procedures (HT1 and HT2) and two DB processes (using burnishing forces of 100 N and 300 N) on the tensile properties and surface integrity of LPBF 17-4PH SS cylindrical samples. The HT2 procedure, including annealing , , solution treatment (, , cooling (), and ageing (, ) led to yield limit, tensile strength, and Vickers hardness values of , , and respectively. The concept presented takes advantage of the combination of the transformation, precipitation and strain-hardening effects. The combined effect was most pronounced in the samples subjected to the HT2 procedure and subsequent DB (300 N), for which a retained austenite fraction of 6.93%, surface microhardness of and the maximum values of the compressive axial and hoop RSs of and , respectively, were measured.

Cut roses (Rosa hybrida L.) are highly sensitive to postharvest conditions, often experiencing quality losses associated with declines in SPAD values (relative chlorophyll index), color instability, Botrytis cinerea incidence, and impaired bud opening. This study aimed to evaluate the effects of different storage atmospheres, including controlled atmosphere (CA; 10% CO2 + 3% O2 and 6% CO2 + 3% O2), normal atmosphere (NA), and modified atmosphere packaging (MAP; LDPE1 (low-permeability MAP): 25 µm, 8000 cc m−2 day−1 O2 permeability; LDPE2 (high-permeability MAP): 25 µm, 12,000 cc m−2 day−1 O2 permeability), on SPAD values, color parameters, disease incidence, and bud development in cut rose cultivars (Rosa hybrida L.) cvs. ‘Rhodos’ and ‘Athena’ harvested in May, June, August, and November. The experiment was conducted as a factorial completely randomized design with seven biological replicates per treatment, each consisting of a single flower. Treatments were applied in combination with 1-methylcyclopropene (1-MCP, 625 ppb) and a commercial postharvest hydrating solution (Chrysal RVB, 1 mL L−1) under storage conditions of 0.5 ± 0.5 °C and 80–85% relative humidity. The results indicated that CA conditions in combination with 1-MCP maintained higher SPAD values, improved color stability, and were associated with lower Botrytis incidence (p < 0.01). In addition, the low-permeability LDPE1-based MAP treatment minimized variations in hue angle (h°) and improved bud development scores, while the hydrating solution treatment promoted bud opening, particularly in cv. ‘Athena’, although its effect on disease suppression was limited. Overall, the combined application of controlled atmosphere storage and 1-MCP generally showed superior performance in maintaining postharvest quality, reducing disease incidence, and preserving the visual and physiological attributes of cut roses, with effects varying depending on cultivar and evaluated parameter.

Diabetic foot ulcers (DFUs) pose a significant global health threat. It is estimated that individuals with diabetes have a 15-34% lifetime risk of developing a foot ulcer. This clinical study evaluates the comparative effectiveness of Hyodine solution versus standard treatment protocols in promoting the healing of DFUs. This prospective, multicenter, single-blind randomized clinical trial enrolled 98 patients with type 1 and 2 diabetes who presented with grade 1-2 infected diabetic foot ulcers from participating diabetes clinics between June 2023 and January 2025. Patients were randomly divided into two groups by block randomization in a 4:1 ratio: a control group that received standard treatment and an intervention group (Hyodine) that received standard treatment plus an iodine solution. Wound cultures were obtained three times during the study: at baseline (before treatment initiation), week 2, and week 4. The collected data were analyzed using SPSS 20 software. In our study, 98 patients with diabetic foot ulcers participated. Intervention group (n = 49): received Hyodine treatment, and the control group (n = 49) received standard wound care, for four weeks. The average age of the participants was 60 ± 11.46 years. Among the participants, 30 patients (30.6%) were females, and 63.3% of the individuals had a history of diabetic foot ulcer. The colony counts significantly decreased by the end of the study compared to the beginning of the study (p<0.001) in the intervention group. The difference in wound area in the Hyodine group between the first and last visits was statistically significant (P < 0.05). These results align with growing evidence that hyaluronic acid-based treatments, such as Hyodine, enhance antimicrobial activity and accelerate wound healing in chronic diabetic foot ulcers. To reduce complications from diabetic foot ulcers, the implementation of advanced therapeutic interventions is critical for alleviating the burden on both patients and healthcare systems. IRCT20088094001199N8.

Rapid solidification by melt-spinning produces aluminum alloys with extremely refined microstructures but also introduces strong structural gradients across the ribbon thickness. In this work, the microstructural evolution of a rapidly solidified Al-Cu-Li-Mg-Sc-Zr alloy was investigated during model homogenization using in situ STEM heating experiments and correlated with bulk electrical-resistivity measurements. The as-cast ribbons exhibit two distinct solidification zones: a near-contact region consisting of columnar cells containing fine Cu-rich spherical precipitates, and a central region composed of larger eutectic cells enriched in Al2Cu and Al7Cu2Fe phases. Stepwise in situ STEM annealing between 200 °C and 500 °C reveals a sequence of transformations, including matrix depletion due to precipitation of strengthening phases, coarsening of primary phases, and formation of Al3(Sc,Zr) dispersoids. Above 500 °C, rapid dissolution of Cu-rich primary phases occurs, leaving only a limited number of stable grain-boundary particles of the Al7Cu2Fe phase, eliminating the original two-zone structure, and resulting in a fully homogenized ribbon. Ex situ annealing confirms that the resulting microstructure is uniform across the ribbon thickness and enables consistent precipitation strengthening during artificial aging. The proposed annealing treatment is based on numerical models for homogenization of eutectic systems. The final annealing step combines homogenization and solution treatment at 530 °C for periods close to 5 min—two orders of magnitude shorter than standard holding times. Microhardness measurements from both ribbon surfaces reveal an identical peak-aged hardness of 135 HV, validating the effectiveness of the short-time homogenization strategy for rapidly solidified Al-Cu-Li-Mg-based alloys.

This study focuses on China’s domestically developed K452 alloy. Using Si3N4 ceramic balls as the counterface material, the tribological properties of the K452 alloy were investigated after heat treatment over a wide temperature range (RT–800 °C), and the wear mechanisms were analyzed. The results show that the heat treatment process enhances the material hardness slightly by promoting the dissolution of the γ′-strengthening phase and the precipitation of the η phase. From RT to 600 °C, the wear rate of the K452 alloy remains at a relatively low level, on the order of 10−6 mm3·m−1·N−1. Compared with the as-cast condition, intermediate treatment exhibits a significant reduction in the wear rate. Compared with traditional processes, it reduces one step of heat treatment. This improvement is attributed to the precipitation of the uniformly fine η phase, along with the re-dissolution of the γ′-strengthening phase. When the testing temperature is raised to 800 °C, the tribological performance of the K452 alloy deteriorates significantly, with the wear rate increasing to the order of 10−5 mm3·m−1·N−1. Microstructural characterization confirms that the in situ formations of dense Cr2O3 and Al2O3 oxide films during friction are the primary mechanism for improved wear resistance from RT to 600 °C. But when the temperature rises to 800 °C, the dynamic equilibrium of the oxide layers is disrupted, leading to oxidative wear becoming the dominant mechanism.

This work examines the micromechanical deformation of GH4169 superalloy, focusing on how δ phase characteristics, including content (area fraction), morphology, and distribution, affect grain scale stress/strain partitioning. By combining microstructural characterization with crystal plasticity finite element modeling, we elucidate the mechanisms behind the unusual mechanical evolution after cold rolling (0–70%) and solution treatment. The results show that higher cold rolling reduction not only raises the area fraction of the δ phase from 0.27% to 4.56% but also alters its morphology and size. The coexisting spheroidal, short-rod-like, and needle-like particles evolve primarily via elongation along the long axis and dissolution along the short axis, resulting in overall coarsening. Concurrently, the distribution shifts from intragranular sites toward grain boundaries and triple junctions. These microstructural evolutions result in hard-soft grain strain partitioning, where strain localizes in hard grains but spreads extensively in soft grains. The significant strength degradation observed at 70% deformation is primarily due to excessive δ phase precipitation, which weakens solid-solution strengthening. Compared to morphology, the distribution of the δ phase exerts a more pronounced influence on slip activation and local stress evolution. Uniformly dispersed intragranular δ particles promote multi-slip activity and effectively regulate matrix stress distribution. • Multiparameter δ Phase Analysis: Breaks through traditional single parameter (volume fraction) limitations by integrating volume fraction, morphology, and distribution of δ phase to understand their coupled influence on GH4169's micromechanical deformation. • Quantitative Processing-Structure-Property Chain: Establishes a novel quantitative correlation chain: Cold Rolling Reduction → δ Phase Characteristics (Content/Morphology/Distribution) → Microscopic Strain Partitioning → Macroscopic Property Evolution, elucidating the processing-microstructure-performance mechanism. • Synergistic CPFEM Inversion & Visualization: Develops a crystal plasticity finite element (CPFEM) model that simultaneously inverts all three δ phase parameters (morphology, distribution, content) and achieves dynamic visualization of microscopic stress/strain fields, capturing the hard-soft grain strain partitioning effect. • Mechanism of Strength Degradation Uncovered: Deciphers the fundamental micromechanical cause (via strain/stress field analysis and strain partitioning) underlying the macroscopic strength degradation observed at high (70%) deformation levels.

Effect of forging temperature and subsequent heat treatment on the microstructure, strength anisotropy, and mechanical properties of the Ti-1300 alloy