Influence of Heat Treatment on Microstructure, Mechanical Properties, and Damping Behavior of 2024 Aluminum Matrix Composites Reinforced by Carbon Nanoparticles.

Nanocarbon 2024 aluminum composites with 0.5 vol. % and 1 vol. % of graphene nanoplatelets and 1 vol. % and 2 vol. % of activated nanocarbon were manufactured through induction casting. The effect of the reinforcements and heat treatment on the performance of the composites was examined. Analysis of the microstructure of the composites before heat treatment suggested the homogeneous dispersion of reinforcements and the absence of secondary carbide or oxide phases. The presence of carbon nanoparticles had a significant impact on the microstructural characteristics of the matrix. This behavior was further enhanced after the heat treatment. The mechanical and damping properties were evaluated with the uniaxial compression test, micro Vickers hardness test, and dynamic mechanical analysis. The yield strength and ultimate strength were improved up to 28% (1 vol. % of graphene nanoplatelets) and 45% (0.5 vol. % of graphene nanoplatelets), respectively, compared to the as-cast 2024 aluminum. Similarly, compared to the heat-treated 2024 aluminum, the composites increased up to 56% (0.5 vol. % of graphene nanoplatelets) and 57% (0.5 vol. % of graphene nanoplatelets) in yield strength and ultimate strength, respectively. Likewise, the hardness of the samples was up to 33% (1 vol. % of graphene nanoplatelets) higher than that of the as-cast 2024 aluminum, and up to 31% (2 vol. % of activated nanocarbon) with respect to the heat-treated 2024 aluminum. The damping properties of the nanocarbon-aluminum composites were determined at variable temperatures and strain amplitudes. The results indicate that damping properties improved for the composites without heat treatment. As a result, it is demonstrated that using small volume fractions of nanocarbon allotropes enhanced the mechanical properties for both with- and without-heat treatment with a limited loss of plastic deformation before failure for the 2024 aluminum matrix.

Quantitative proteomic analysis for characterization of protein components related to dough quality and celiac disease in wheat flour, dough, and heat-treated dough.

High-sensitivity 4D label-free proteomic technology was used to identify protein components related to gluten quality and celiac disease (CD) in strong-gluten wheat cultivar KX 3302 and medium-gluten wheat cultivar BN 207. The highly expressed storage protein components in KX3302 were high-molecular-weight-glutenin-subunits (HMW-GSs), α-gliadin, and globulin, whereas those in BN207 were γ-gliadin, low-molecular-weight-glutenin-subunits (LMW-GSs) and avenin-like proteins. In addition, BN207 had more upregulated metabolic proteins than KX3302. The abundance of storage proteins increased during dough formation. After heat treatment, the upregulated proteins accounted for 57.53 % of the total proteins, but the downregulated storage proteins accounted for 79.34 % of the total storage proteins. In cultivar KX3302, CD proteins mainly included α-gliadin and HMW-GSs, whereas in BN207, they were mainly γ-gliadin and LMW-GSs. Thermal treatment significantly reduces the expression levels of CD-related proteins. These findings provide a new perspective on reducing the content of CD-related proteins in wheat products.

Intracellular pyruvate as one of the major bioactive substances of lactic acid bacteria isolated from kimchi.

The present study aimed to identify the metabolites associated with the physiological activity of kimchi-derived lactic acid bacteria (LAB). A clear difference was observed between the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging rates when the pyruvate content was high (273.5 ng/µL; radical removal speed 6.50% per min) and the rates when the pyruvate content had decreased (131.9 ng/µL; radical removal speed 3.63% per min). Additionally, the characteristics of LAB antioxidant activity (increase in ABTS radical scavenging activity with reaction time, low level of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity) were similar to those of pyruvate-derived activity. Hydrogen peroxide content (WiKim0124, 2.08 → 0.26; WiKim0121, 0.99 → 0.47; WiKim39, 1.93 → 0.24) and lactate dehydrogenase activity (WiKim0124, 1.53 → 0.00; WiKim0121, 0.73 → 0.01; WiKim39, 1.72 → 0.02) decreased more in heat-killed LAB than in non-heat-killed LAB. Accordingly, this resulted in increased pyruvate content and the inhibitory activity of lipid peroxide production increased by 2-3 times. Our findings indicate that pyruvate is one of the major metabolites regulating LAB physiological activity. PRACTICAL APPLICATION: The safety of utilizing live probiotics remains a topic of debate. To mitigate associated risks, there is a growing interest in non-viable microorganisms or microbial cell extracts for use as probiotics. Various methods can be employed for probiotic inactivation. Heat treatment typically emerges as the preferred choice for inactivating probiotic strains in many instances. The present study shows the distinctions between inactivating lactic acid bacteria (LAB) through heat treatment and non-heat treatment. It may serve as a valuable reference for selecting an appropriate inactivation method for LAB in industrial processes.

Effect of microwave combined with ethanol pretreatment on the quality of potato CO2 explosion puffing drying.

To enhance the drying quality of potato slices, this investigation employed a microwave heating (MH) combined with ethanol osmotic dehydration (EOD) pretreatment strategy to improve the quality of explosion puffing drying (EPD). This paper systematically investigated the effects of different pretreatment methods (no treatment, HAD, MH, EOD, MH+EOD) on the quality and physicochemical properties of potato slices subjected to CO2-EPD. The results showed that after MH and EOD pretreatments, the internal pores of the potato slices exhibited a uniform porous structure. The MH+EOD+CO2-EPD treatment demonstrated superior expansion, crispness, hardness, and color, with higher retention rates of vitamin C and protein. The measurements were an expansion ratio of 2.15, hardness of 1290.01 g, crispness of 745.94 g, ΔE of 6.54, protein content of 1.99 g/100 g, and VC content of 17.33 mg/100 g. Additionally, the study explored the effects of microwave power, microwave drying time, ethanol concentration, and ethanol soaking time on the expansion ratio, hardness, crispness, protein content, VC content, and color. MH+EOD+CO2-EPD is an environmentally sustainable and efficient solution with potential for widespread industrial application to enhance processing quality and economic benefits.

Impact of heat treatment on the flavor stability of Longjing green tea beverages: Metabolomic insights and sensory correlations.

The flavor stability of tea beverages during storage has long been a concern. The study aimed to explore the flavor stability of Longjing green tea beverage using accelerated heat treatment trials, addressing the shortage of lengthy storage trials. Sensory evaluations revealed changes in bitterness, umami, overall harmonization, astringency, and ripeness as treatment duration increased. Accompanied by a decrease in L-values, ΔE and an increase in a and b-values. Seventeen non-volatile metabolites and three volatile metabolites were identified differential among samples by metabolomics, with subsequent correlation analysis indicating associations between sensory attributes and specific metabolites. Umami was linked to epigallocatechin 3,5-digallate and alpha-D-glucopyranose, astringency was correlated with ellagic acid and 1-ethyl-1H-pyrrole. Ripeness showed associations with ellagic acid, 6,7-dihydroxycoumarin, heptanal, and benzaldehyde, and overall harmonization was linked to 6,7-dihydroxycoumarin, ß-myrcene, α-terpineol, and heptanal. A series of verification tests confirmed the feasibility of accelerated heat treatment trials to replace traditional storage trials. These results offer valuable insights into unraveling the complex relationship between sensory and chemical profiles of green tea beverages.

Modulating rice digestibility: Mechanisms of ultrasound, oleic acid and moist-heat treatments influence structural, physicochemical and digestive properties.

The research compared the combined effect of ultrasound (160 W, 2 min), oleic acid (15%, 11 h), and moist-heat treatment (HMT, 25% moisture content, 110 °C, 2 h) with their individual treatment on rice grains. The results showed that ultrasound treatment created pores and cracks in the rice grains, facilitating an easier penetration for oleic acid to develop amylose-oleic acid complex during HMT. Compared to native raw rice (NR), both single and combined treatments significantly altered the morphology, reduced swelling power and solubility, enhanced hydrophilicity, thus changing the moisture distribution, thermal and pasting characteristics. Notably, the combined treatment of three techniques significantly increased the relative crystallinity, accompanied by the highest digestive resistance, and the content of resistant starch was increased from 20.53% in NR to 31.75%, much higher than the other treatments. These findings provide potential for the manufacturers to rationally and flexibly employ this low digestible rice in health food products.

Impact of heat and high-moisture pH treatments on starch digestibility, phenolic composition, and cell bioactivity in sorghum (Sorghum bicolor L. Moench) flour.

Sorghum (Sorghum bicolor L. Moench), characterized by substantial genetic diversity, encompasses some lines rich in health-promoting polyphenols. Laboratory studies have demonstrated anticancer properties of sorghum phenolics; however, their presence may impact nutritional factors, such as digestible starch. The objective of this study was to determine the effects of pH and high-moisture heating on starch digestibility, phenolic profile, and anticancer activity in sorghum. High Phenolic sorghum flour line SC84 was combined with buffer solutions (pH 3, 4, 5, 7, and 8) and heated for 0, 10, 30, 60, or 120 min. Starch digestibility was assessed using the K-DSTRS kit from Megazyme. Changes in phenolic composition were analyzed using total phenolic content (TPC) and condensed tannin content (CTC) assays coupled with reversed phase high performance liquid chromatography (RP-HPLC) analysis. Anticancer potential against human colorectal cancer cells (HCT116 and SW480) was determined though cell viability assay. Results indicated a significant increase in total starch digestibility of sample after heating. Heating samples for 10 min did not significantly reduce TPC of samples. However, CTC was significantly reduced with heating time, while pH exhibited no significant effect on CTC. The measured 3-deoxyanthocyanidins experienced a significant decrease (p < 0.0001), while certain flavonoids increased significantly (p < 0.05) after heating for 30 min or longer. Notably, the 10 min heating duration minimally affected anticancer activity, whereas longer heat times diminished extract efficacy against human colorectal cancer cells. Alkaline pH levels significantly decreased anticancer activity, regardless of heating time. Importantly, heating sorghum for 10 min improved starch digestibility with minimal compromise to potential health benefits. These findings suggest promising implications for the development of high-phenolic sorghum products, and provide valuable insights to guide forthcoming animal and clinical studies. The demonstrated impact of wet-heating on increased starch digestibility, coupled with the preservation of phenolic content and bioactivity, underscores the potential of incorporating high-phenolic sorghum lines in future functional food formulations.

Beverage of Brazil Nut and Bocaiuva Almond Enriched with Minerals: Technological Quality and Nutritional Effect in Male Wistar Rats.

The objective of this work was to evaluate the properties of beverages formulated with Brazil nuts (Bertholletia excelsa Bonpl) and bocaiuva almonds (Acrocomia aculeata (Jacq.) Lodd. Ex Mart.). Five beverages were developed with Brazil nut, bocaiuva almond, and water (m/m/v), as follows: (i) NB, nut:water, 1:10; (ii) AB, almond:water, 1:10; (iii) NAB1, 1:0.1:10, nut:almond:water; (iv) NAB5, nut:almond:water, 1:0.5:10; and (v) NAB10, nut:almond:water, 1:1:10. The physicochemical, chemical, technological, and microbiological parameters were evaluated. After heat treatment (HT) and enrichment with minerals, the beverages that demonstrated stability in these characteristics were tested in a biological assay. The physical and biochemical parameters of male Wistar rats were evaluated after administering beverages for 28 days. HT decreased the total phenolic content and the antioxidant activity; however, it guaranteed microbiological safety. Mineral supplementation changed the colors and increased the pH values of the beverages. After the beverages were administered, the Wistar rats in the (i) NB group showed decreases in retroperitoneal adipose tissue, total cholesterol, and triglycerides; (ii) those in the AB group exhibited decreased triglycerides contents; and (iii) those in the NAB10-group presented decreased liver weights. The beverages evaluated in this study demonstrate a protective effect against risk factors such as fat accumulation in the liver, retroperitoneal adipose tissue, and hypercholesterolemia.

Extraction of egg yolk lipids via salt-induced synergistic heat treatment: Fabrication, characterization and flavor analysis.

In this study, the oxidation of egg yolk lipids (EYL) by salt-induced heat and non-heat treatments was investigated for quality and flavor. The correlation between physicochemical properties, lipid oxidation and antioxidant activity was modeled using partial least squares discriminant analysis (PLS-DA). The results indicated that the prolonged salt-induced synergistic heat treatment produced the highest level of lipid oxidation, antioxidant activity and oil exudation, along with the lowest level of polyunsaturated fatty acid content. In addition, higher contents of pyrazines and fewer acid species were detected, which was not the case with the salt-free heat treatment. In total, 14 identical volatile organic compounds (VOCs) were produced, yet their overall flavor profiles determined by the electronic nose would remain dramatically distinguished. Therefore, heat treatment was particularly critical for lipid oxidation and the generation of aromatic compounds, implying that heat-treated EYL induced by salt is a flavor component with good antioxidant potential.

Streamlined on-column refolding and purification of nanobodies from inclusion bodies expressed as fusion proteins.

This study introduces an efficient on-column refolding and purification method for preparing nanobodies (Nbs) expressed as inclusion bodies and fusion proteins. The HisTrapTM FF system was successfully employed for the purification of the fusion protein FN1-ΔI-CM-2D5. The intein ΔI-CM cleavage activity was activated at 42 °C, followed by incubation for 4 h. Leveraging the remarkable thermal stability of Nbs, 2D5 was further purified through heat treatment at 80 °C for 1h. This method yielded up to 107.2 mg of pure 2D5 with a purity of 99.2 % from just 1L of bacterial culture grown in a shaker flask. Furthermore, this approach successfully restored native secondary structure and affinity of 2D5. Additionally, the platform was effectively applied to the refolding and purification of a polystyrene-binding nanobody (B2), which exhibited limited expression in the periplasmic and cytoplasmic spaces of E. coli. This endeavor resulted in the isolation of 53.2 mg of pure B2 Nb with a purity exceeding 99.5 % from the same volume of bacterial culture. Significantly, this approach restored the native secondary structure of the Nbs, highlighting its potential for addressing challenges associated with expressing complex Nbs in E. coli. Overall, this innovative platform provides a scientifically rigorous and reproducible method for the efficient preparation of Nbs, offering a valuable tool for antibody research and development.

Increasing the Strength and Impact Toughness of Carbon Steel Using a Nanosized Eutectoid Resulting from Time-Controlled Quenching.

High-carbon steels are normally used as tool materials. The use of such steels for construction is limited due to their increased brittleness and poor weldability. However, it appears that high-carbon steels possess certain hidden reserves for enhanced plasticity and strength if properly heat-treated. An unconventional heat treatment was applied to carbon eutectoid steel (0.8 wt.% C) in order to increase its strength and impact toughness simultaneously. Samples for tensile and impact testing were held at 800 °C for different time ranges from 3 min to 9 min with subsequent cooling in oil. It was established that for each type of sample, an optimal holding time exists that is responsible for increased strength and high impact toughness. The hardness and microhardness levels of the surface and under-surface regions of the samples reached 390 HV after optimal heat treatment. An X-ray revealed a shift of the (211)α-peak to the lower 2-theta angles after heat treatment with the optimal holding time; this indicates an increase in carbon content in alpha solid solutions of approximately 0.12 wt.%. Thus, a nanostructured mixture of low-carbon martensite and thin cementite plates is formed in the under-surface region of carbon eutectoid steel after heat treatment, with a controlled holding time at the austenitizing temperature.

Influence of Post-Weld Heat Treatment on Mechanical Properties and Microstructure of Plasma Arc-Welded 316 Stainless Steel.

This study investigates the effects of post-weld heat treatment (PWHT) on the microstructures and mechanical properties of plasma arc-welded 316 stainless steel. The experimental parameters included the solid solution temperatures of 650 °C and 1050 °C, solid solution durations of 1 h and 4 h, and quenching media of water and air. The mechanical properties were evaluated using Vickers hardness testing, tensile testing, scanning electron microscopy (SEM), and optical microscopy (OM). The highest ultimate tensile strength (UTS) of 693.93 MPa and Vickers hardness of 196.4 in the welded zone were achieved by heat-treating at 650 °C for one hour, quenching in water, and aging at 500 °C for 24 h. Heat-treating at 650 °C for one hour, followed by quenching in water and aging at 500 °C for 24 h results in larger dendritic δ grains and contains more σ phase compared to the other conditions, resulting in increased strength and hardness. Additionally, it shows wider and shallower dimple structures, which account for its reduced impact toughness.

Modulation of Interlayer Nanochannels via the Moderate Heat Treatment of Graphene Oxide Membranes.

In response to the phenomenon of interlayer transport channel swelling caused by the hydration of oxygen-containing functional groups on the GO membrane surface, a moderate heat treatment method was employed to controllably reduce the graphene oxide (GO) membrane and prepare a reduced GO composite nanofiltration membrane (mixed cellulose membrane (MCE)/ethylenediamine (EDA)/reduced GO-X (RGO-X)). The associations of different heat treatment temperatures with the hydrophilicity, interlayer structure, permeability and dye/salt rejection properties of GO membranes were systematically explored. The results indicated that the oxygen-containing groups of the GO membrane were partially eliminated after heat treatment, and the hydrophilicity was weakened. This effectively weakened the hydration between the GO membrane and the water molecules and inhibited the swelling of the oxidized graphene membrane. In the dye desalination test, the MCE/EDA/RGO membrane exhibited an ultra-high rejection rate of over 97% for methylene blue (MB) dye molecules. In addition, heat treatment increased the structural defects of the GO membrane and promoted the fast passage of water molecules via the membrane. In pure water flux testing, the water flux of the membrane remained above 46.58 Lm-2h-1bar-1, while the salt rejection rate was relatively low.

Effect of dry- and moist-heat treatment processes on the structure, solubility, and in vitro digestion of macadamia protein isolate.

This study aimed to enhance the solubility and digestibility of macadamia protein isolate (MPI) for potential utilization in the food industry. The impact of dry- and moist-heat treatments at various temperatures (80, 90, and 100°C) and durations (15 and 30 min) on macadamia protein's microstructure, solubility, molecular weight, secondary and tertiary structure, thermal stability, and digestibility were investigated and evaluated. The heating degree was found to cause roughening of the MPI surface. The solubility of MPI after dry-heat treatment for 15 min at 100°C reached 290.96 ± 2.80% relative to that of untreated protein. Following heat treatment, the bands of protein macromolecules disappeared, while MPI was stretched by vibrations of free and hydrogen-bonded hydroxyl groups. Additionally, an increase in thermal stability was observed. After heat treatment, hydrophobic groups inside the protein are exposed. Heat treatment significantly improved the in vitro digestibility of MPI, reaching twice that of untreated protein. The results also demonstrated that dry- and moist-heat treatments have distinct impacts on MPI, while heating temperature and duration affect the degree of modification. With a decreased ordered structure and increased random coil content, the dry-heat treatment significantly enhanced the in vitro digestibility of MPI. The digestibility of MPI after dry-heat treatment for 30 min at 90°C increased by 77.82 ± 2.80% compared to untreated protein. Consequently, compared to moist-heat treatment, dry-heat treatment was more effective in modifying macadamia protein. Dry-heat treatment of 30 min at 90°C was determined as the optimal condition. PRACTICAL APPLICATION: Heat treatment enhances MPI characteristics, potentially advancing macadamia-derived food production, including plant-based beverages and protein supplements.

Optimization of machining parameters for turning operation of heat-treated Ti-6Al-3Mo-2Nb-2Sn-2Zr-1.5Cr alloy by Taguchi method.

TC21 alloy is a high-strength titanium alloy that has been gaining attention in various industries for its excellent combination of strength, toughness, and corrosion resistance. Given that this alloy is hard to cut material, therefore this study aims to optimize the process parameters of Turing this alloy under different conditions (i.e. as-received alloy, and heat-treated alloy). The L9 Taguchi approach-base orthogonal array is used to determine the optimum cutting parameters and the least number of experimental trials required. The achievement of this target, three different cutting parameters are used in the experimental work; each cutting parameter has three levels. The cutting speeds are chosen as 120, 100, and 80 m/min. The feed rates' values are 0.15, 0.1, and 0.05, mm/rev, and the depth of cut values are 0.6, 0.4, and 0.2 mm. After applying three steps of heat treatment (First step: is heating the sample to 920 °C for 1 h then decreasing to 820 °C also for 1 h, second step: cooling the sample to room temperature by water quenching (WQ), the third step: holding the sample at 600 °C for 4 h (Aging process)). The results revealed that the triple heat treatment led to the change in the microstructure from (α + ß) to (α + ß) with secondary α platelets (αs) formed in residual ß matrix leading to a decreased surface roughness by 56.25% and tool wear by 24.18%. The two most critical factors that affect the tool insert wear and surface roughness are the death of cut and cutting speed, which contribute 46.6% and 46.7% of the total, respectively. Feed rate, on the other hand, has the least importance, contributing 20.2% and 31.9% respectively.

Protective Effects of Laminaria japonica Polysaccharide Composite Microcapsules on the Survival of Lactobacillus plantarum during Simulated Gastrointestinal Digestion and Heat Treatment.

To improve probiotics' survivability during gastrointestinal digestion and heat treatment, Lactobacillus plantarum was microencapsulated by spray-drying using Laminaria japonica polysaccharide/sodium caseinate/gelatin (LJP/SC/GE) composites. Thermogravimetry and differential scanning calorimetry results revealed that the denaturation of LJP/SC/GE microcapsules requires higher thermal energy than that of SC/GE microcapsules, and the addition of LJP may improve thermal stability. Zeta potential measurements indicated that, at low pH of the gastric fluid, the negatively charged LJP attracted the positively charged SC/GE, helping to maintain an intact microstructure without disintegration. The encapsulation efficiency of L. plantarum-loaded LJP/SC/GE microcapsules reached about 93.4%, and the survival rate was 46.9% in simulated gastric fluid (SGF) for 2 h and 96.0% in simulated intestinal fluid (SIF) for 2 h. In vitro release experiments showed that the LJP/SC/GE microcapsules could protect the viability of L. plantarum in SGF and release probiotics slowly in SIF. The cell survival of LJP/SC/GE microcapsules was significantly improved during the heat treatment compared to SC/GE microcapsules and free cells. LJP/SC/GE microcapsules can increase the survival of L. plantarum by maintaining the lactate dehydrogenase and Na+-K+-ATPase activity. Overall, this study demonstrates the great potential of LJP/SC/GE microcapsules to protect and deliver probiotics in food and pharmaceutical systems.

Effect of Continuous Casting and Heat Treatment Parameters on the Microstructure and Mechanical Properties of Recycled EN AW-2007 Alloy.

The growing use of aluminum and its compounds has increased the volume of aluminum waste. To mitigate environmental impacts and cut down on manufacturing expenses, extensive investigations have recently been undertaken to recycle aluminum compounds. This paper outlines the outcomes of a study on fabricating standard EN AW-2007 alloy using industrial and secondary scrap through continuous casting. The resultant recycled bars were analyzed for their chemical makeup and examined for microstructural features in both the cast and T4 states, undergoing mechanical property evaluations. The study identified several phases in the cast form through LM, SEM + EDS, and XRD techniques: Al7Cu2Fe, θ-Al2Cu, ß-Mg2Si, Q-Al4Cu2Mg8Si7, and α-Al15(FeMn)3 (SiCu)2, along with Pb particles. Most primary intermetallic precipitates such as θ-Al2Cu, ß-Mg2Si, and Q-Al4Cu2Mg8Si7 dissolved into the α-Al solid solution during the solution heat treatment. In the subsequent natural aging process, the θ-Al2Cu phase predominantly emerged as a finely dispersed hardening phase. The peak hardness achieved in the EN AW-2007 alloy was 124.8 HB, following a solution heat treatment at 500 °C and aging at 25 °C for 80 h. The static tensile test assessed the mechanical and ductility properties of the EN AW-2007 alloy in both the cast and T4 heat-treated states. Superior strength parameters were achieved after solution heat treatment at 500 °C for 6 h, followed by water quenching and natural aging at 25 °C/9 h, with a tensile strength of 435.0 MPa, a yield strength of 240.5 MPa, and an appreciable elongation of 18.1% at break. The findings demonstrate the feasibility of producing defect-free EN AW-2007 alloy ingots with excellent mechanical properties from recycled scrap using the continuous casting technique.

Effects of Cr Addition on the Microstructure and Mechanical Properties of an Al-Si-Cu-Mg Alloy.

The effects of chromium (Cr) addition ranging 0.1-0.3 wt.% on the microstructure and mechanical properties of Al-7Si-4Cu-0.25Mg (wt.%) alloy have been investigated. The cast Cr-free alloy consisted of α-Al, eutectic Si, Q-Al5Mg8Cu2Si6 and θ-Al2Cu phases. Doping of Cr resulted in the appearance of a polyhedron-shaped α-Al13Cr4Si4 phase with a cubic structure. The Al13Cr4Si4 particles were found to embed with Al2Cu blocks and bring about size reduction for the Al2Cu blocks. The area fraction of Al13Cr4Si4 monotonously increased with Cr content. After T6 treatment, the Al2Cu blocks almost fully dissolved and transformed to θ'-Al2Cu precipitates in the Cr-containing alloys. TEM observation revealed relatively large-sized θ' precipitates attached to Al13Cr4Si4 dispersoids. The Cr-containing alloys showed impressive mechanical properties, with the peak strength up to 452 MPa at room temperature. The ductility exhibited an increasing trend with Cr content, but the strength dropped dramatically when the Cr content reached 0.3 wt.%. It is suggested that the strength contribution from the Al13Cr4Si4 phase is limited, especially at an elevated temperature.

Microstructural Evolution of Quaternary AlCoCrNi High-Entropy Alloys during Heat Treatment.

This study examines the microstructural evolution and mechanical properties of quaternary AlCoCrNi high-entropy alloys after heat treatment at 873 K for 72 and 192 h. The changes in nanostructure and phase transformation based on the heat treatment duration were as follows: B2 dendrite + BCC interdendrite and sigma phases after 72 h; B2 dendrite and interdendritic sigma phases + BCC after 192 h. After annealing, the morphology of the dendritic region shifted from spherical to needle-like, and the interdendritic region transformed from a spinodal-like to a plate-like morphology. Additionally, a phase transformation was observed in the dendritic regions of the annealed alloys at the nano-scale. The presence of the sigma phase in AlCoCrNi high-entropy alloys significantly improved the yield strength to around 1172 MPa; nevertheless, it decreased the compressive strain rapidly to 0.62%.

The Integration of ANN and FEA and Its Application to Property Prediction of Dual-Performance Turbine Disks.

Regulating the microstructure of powder metallurgy (P/M) nickel-based superalloys to achieve superior mechanical properties through heat treatment is a prevalent method in turbine disk design. However, in the case of dual-performance turbine disks, the complexity and non-uniformity of the heat treatment process present substantial challenges. The prediction of yield strength is typically derived from the analysis of microstructures under various heat treatment regimes. This method is time-consuming, expensive, and the accuracy often depends on the precision of microstructural characterization. This study successfully employed a coupled method of Artificial Neural Network (ANN) and finite element analysis (FEA) to reveal the relationship between the heat treatment process and yield strength. The coupled method accurately predicted the location specified and temperature-dependent yield strength based on the heat treatment parameters such as holding temperatures and cooling rates. The root mean square error (RMSE) and mean absolute percentage deviation (MAPD) for the training set are 50.37 and 3.77, respectively, while, for the testing set, they are 50.13 and 3.71, respectively. Furthermore, an integrated model of FEA and ANN is established using a Abaqus user subroutine. The integrated model can predict the yield strength based on temperature calculation results and automatically update material properties of the FEA model during the loading process simulation. This allows for an accurate calculation of the stress-strain state of the turbine disk during actual working conditions, aiding in locating areas of stress concentration, plastic deformation, and other critical regions, and provides a novel reliable reference for the rapid design of the turbine disk.