Increasing Aluminum Content Research Articles

Experimental study on compression mechanical properties of functionally graded shape memory alloys

Functionally graded shape memory alloy (FG-SMA) hold considerable promise for diverse applications in aerospace and micro electro mechanical system (MEMS) fields, owing to their elevated ceramic hardness and distinctive phase transition characteristics. To investigate the mechanical properties and phase transition behaviors of FG-SMA, an FG-SMA specimen was fabricated for the first time using the spark plasma sintering and ball-mill mixing method. Subsequently, microstructure, phase transformation, hardness, compression fracture and shape memory effect testing experiments were carried out. The results revealed a microstructure of the FG-SMA without noticeable pores in the alumina content range of 0.1% to 0.6%. Alumina particles were effectively integrated into the NiTi matrix, enhancing the FG-SMA’s compressive strength. Varied alumina gradients in the FG-SMA cross-section led to distinct phase transitions. The addition of alumina increased the hardness of the NiTi matrix, resulting in higher fracture stress and strain in the FG-SMA. The elastic recovery strain of FG-SMA augmented with increasing alumina content, although the recoverable strain associated with the shape memory effect gradually decreased. This study provides valuable insights for the preparation, optimization, and practical applications of FG-SMAs. At the same time, the research in this article can lay an experimental foundation for the application of FG-SMA in the field of aerospace and MEMS.

Optimization of AlGaAs barrier for InGaAs quantum wells emitting in the near infrared

The results of a study aimed at optimizing the optical properties of InGaAs quantum well structures by employing different barrier designs are presented. Single rectangular InGaAs quantum wells with approximately 21% indium and AlGaAs barriers, with different Al content 12, 20 and 30%, were theoretically modelled using the nextnano3 software to calculate band edges and levels in the quantum wells. A series of samples were grown using molecular beam epitaxy to clarify the influence of the Al fraction in the AlGaAs barriers on the optical properties of the quantum structures. Atomic force microscopy measurements were used to evaluate the surface roughness of the grown structures, while photoluminescence investigations provided insight into the optical quality and carrier confinement effects. The investigations revealed that the introduction of AlGaAs barriers resulted in an increased carrier confinement inside of the quantum well, but consequently resulted in the degradation of the InGaAs quantum well quality with the increase of aluminium content in the barrier. It was determined that a barrier with 12% of Al can be used to balance these effects, by providing a sufficient confinement, while retaining a satisfactory crystalline quality of the quantum structures.

Exposure Test of Various Zinc-Coated Steel Sheets and Corrosion Resistance Evaluation of Zinc-Based Corrosion Products in Japan

Hot-dip zinc-coated steel sheets are widely used because of their high corrosion resistance, long-lasting effects, and low cost. In addition, aluminum and magnesium have been added to hot-dip zinc-coated steel sheets to improve corrosion resistance, and their use is expanding to supported stand of photovoltaic modules and gratings for infrastructure facilities. However, the corrosion resistance of each plated steel sheet has not been evaluated and only a few studies have compared them. Therefore, 10-year exposure tests were performed at six locations in Japan and the corrosion weight loss of each plated steel sheet was measured and compared with those of other plated steel sheets. In addition, the polarization curves of unexposed plated steel sheets and those exposed for five years were measured by linear sweep voltammetry (LSV), and the changes in corrosion resistance due to the corrosion products were verified.Exposure sites were selected based on airborne salinity, the presence or absence of highways (in industrial areas), and the presence or absence of volcanoes. Exposure began in April 2013; specimens were collected 1, 2, 3, 5, and 10 years later. The exposed specimens were hot-dip zinc-coated (Zn), hot-dip zinc-5% aluminum alloy-coated (5% AlZn), hot-dip 55% aluminum-zinc alloy-coated (55% AlZn), and hot-dip zinc-aluminum-magnesium alloy-coated steel sheets (ZnAlMg). The collected specimens were observed externally, photographed, and their corrosion weight losses and electrochemical properties measured. The corrosion weight loss was measured by immersing the collected specimen in a chromic acid-based rust-removal solution to remove the corrosion products, and subsequently comparing the weight of the specimen before and after the removal of the corrosion products. However, when the corrosion products of carbon steel as the matrix (red rust) were obtained over the entire area of the specimens, the plating layer was regarded as almost dissolved, and the corrosion weight loss was not measured. For electrochemical measurements, LSV of the collected specimens was performed in a 0.1 M Na2SO4 solution. For this measurement, an O-ring with a diameter of 1 cm was used to expose only the part of the specimen in contact with the solution.The corrosion weight loss in the various specimens increased with increasing airborne salinity; However, the corrosion weight loss at the exposure site where the volcano was located was the largest. Corrosion weight loss is assumed to be affected more by volcanoes than by airborne salinity. In addition, almost no effect of the presence or absence of highways was present (in industrial areas). The corrosion weight loss increased in the order of Zn, 55% AlZn, 5% AlZn, and ZnAlMg at several exposure sites, but increased in the order of Zn, 5% AlZn, ZnAlMg, and 55% AlZn at the volcanic exposure site. Therefore, the specimens at the exposure sites with and without volcanoes were compared where the average annual airborne salinity was 1 mg dm-2 day-1 or more. The results of LSV of these specimens in 0.1 M Na2SO4 solution are shown in Fig. 1. These results indicate that the corrosion products created at the volcanic exposure site inhibited the dissolution of the plating layer. In addition, aluminum is required to obtain an inhibitory effect on the dissolution of the plating layer owing to corrosion products, and this inhibitory effect improves with increasing aluminum content in the plating layer. Figure 1

Diffusion Behavior and Kinetics for the Vapor Phase Infiltration of Trimethylaluminum in Poly(ethylene oxide): An In Situ Quartz Crystal Microgravimetry Study.

Vapor phase infiltration (VPI) facilitates the incorporation of inorganic components into organic polymers, emerging as an effective technique for fabricating organic-inorganic hybrid materials. However, the complexity of diffusion behavior during the VPI process presents challenges in studying diffusion kinetics, particularly for highly reactive precursor-polymer systems such as trimethylaluminum (TMA) and poly(ethylene oxide) (PEO). In this study, we investigate the VPI process of TMA in PEO using in situ quartz crystal microgravimetry (QCM), which enables measurement of diffusion behavior and kinetics with high precision due to its high temporal resolution. Our results indicate that the VPI process consists of two main regions: a rapid diffusion process, corresponding to the initial penetration of the precursor into the film, followed by a slower relaxation process, attributed to the ongoing chemical reaction. The equivalent diffusion coefficient (De) was estimated to be on the order of 10-9 cm2/s and decreased with increasing aluminum content. Using energy application as a proof-of-concept, when optimized, VPI-modified PEO films were successfully utilized as solid polymer electrolytes (SPEs) for lithium metal batteries (LMBs), showcasing superior performance in mitigating lithium dendrite growth. This study offers valuable insights into the VPI process for PEO-TMA systems and provides guidance for optimizing VPI conditions to enhance the performance of advanced materials.

Influence of alumina on the performance of Ag/ZnO based catalysts for carbon dioxide hydrogenation

We study silver-zinc oxide type catalysts with and without the addition of alumina and perform structural analysis and activity tests for the hydrogenation of carbon dioxide. Adding alumina has a dispersing effect on the zinc oxide without structurally altering the silver phase. An alumina-surface enriched ZnO/Al2O3 phase is observed with an increased surface reducibility. Ag/ZnO has a high selectivity towards carbon monoxide (63 ± 12 %) and methane (24 ± 3 %) and low selectivity towards methanol (13 ± 0.5 %). Operando infrared (SSITKA-FTIR) and mass spectrometric product detection indicate methane formation via an adsorbed carbon monoxide (COads) intermediate. The selectivity changes gradually with increasing alumina content, up to 80 ± 3 % toward methanol, and 20 ± 4 % carbon monoxide without methane detection, combined with a tripling of the space time yield to 0.65 ± 0.02mmolMeOH*gcat-1*h−1 at 250 °C and 30bar. Kinetic analysis suggests that the selectivity change originates from hindering the CO-pathway, while the formate pathway leading to methanol remains active.

Impact of Al3+ substitution on structural, Raman, transport electromagnetic properties of LiFe2O4 nanoparticles

Nanocrystalline Li0.5AlxFe2.5-xO4(x = 0.0 to 0.8 in steps, x = 0.2) compounds were prepared using the sol-gel auto-combustion technique. X-ray diffraction (XRD) analysis confirmed the single-phase cubic spinel structure, which showed that the lattice constant changed significantly, especially in the x = 0.6 sample, where it decreased clearly. The crystallite size decreased with increasing Aluminium content, reaching a small value of about 5 nm for the composition x = 0.8 sample. Raman peaks of pure LiFe2O4 were determined in both phases (alpha and beta), while smaller peaks at 198 and 236 cm−1 that related to the alpha phase were distinguished. All peaks diminished in intensity after Al3+ ions were doped to LiFe2O4 except for the peak at 700, where it became predominantly. The bandgap of the samples was deduced and analyzed from Tauc's plot according to UV–Vis spectra. The change in the electronic structure of the Li-Al ferrites, at which the size of the ferrite becomes close to the de Broglie wavelength, results in a band gap for the Al replaced by LiFe2O4 with different electronic configurations. The variation of the fundamental part of the dielectric constant (ε′), loss tangent (tan δ), and AC conductivity with frequency has been discussed with composition. The increase in Al3+ ion content affected the coercive force, as it decreased, while the saturation magnetism increased when adding Aluminium (x = 0.2) and then began to decline gradually.

Influence of Low-Energy High-Current Electron Beam Exposure on the Phase Composition and Corrosion Resistance of the AM60 Magnesium Alloy

The surface of an AM60 (Al – 5.5, Zn – 0.2, Cu – 0.009, Fe – 0.005, Si – 0.1; Ni – 0.002, Mn – 0.3 wt.%, Mg – the rest) magnesium alloy was exposed to a low-energy high-current electron beam. After the irradiation, the content of the β-phase (Mg17Al12) decreases and the aluminum content increases in the alloy surface layer. After the exposure to the electron beam, the corrosion resistance of the alloy in a 1-molar NaCl solution increases significantly compared to the initial state. The physical reason for the increase in the alloy corrosion resistance after exposure to the electron beam is the higher corrosion resistance of the oxide film formed on the alloy surface due to the increased aluminum content.

Impact of MgO-ZnO substitution on nucleation of aluminosilicate glasses

The nucleation mechanisms is of technically interest and important in glass-ceramics production. Here we investigate the nucleation behaviors of NiO-doped MgO-Al2O3-SiO2 and ZnO-Al2O3-SiO2 glasses. It is found that crystallization tends to takes place on the surface and the interior of glasses for the former and the latter, respectively. The origin of different nucleation behavior is studied by comparing aluminum coordination, configurational entropy and rheological properties of the glasses. The substitution of MgO by ZnO leads to increase of tetrahedral aluminum concentration, and decrease of configurational entropy above glass transition temperature, in particular, the latter is closely related to volume nucleation. In addition, the qualitative comparison of thermodynamic and kinetic barriers of steady-state nucleation rate of two glasses indicates that ZnO-bearing aluminosilicate glass possesses higher diffusivity and lower critical nucleus size, which favoring volume nucleation.

LLDPE/TiO2 composites with high UV aging resistance and mechanical properties by controlling the alumina coating on TiO2

AbstractFor preparing high performance LLDPE film, the photocatalytic activity and the UV absorption capacity of TiO2 were regulated by the alumina coating content on the surface of TiO2. Alumina‐coated TiO2 was prepared by the chemical liquid deposition method, and characterized by element analysis, TGA, FTIR, and morphology observation. The alumina coating layer had been proven to covalently bind to the surface of TiO2 through AlOTi bonds, which formed a continuous and dense coating layer, followed by forming a loose flocculent coating layer with the increase of alumina content. The alumina coating layer could significantly reduce the formation of carbonyl group on the LLDPE chains, and enhance UV aging resistance of LLDPE by inhibiting the photocatalytic activity of TiO2. Moreover, the dispersion of alumina‐coated TiO2 in the LLDPE matrix was improved. Thus, the transmittance of LLDPE/alumina‐coated TiO2 composites was reduced and the whiteness was improved. Importantly, the continuous and dense alumina coating layer was enough to inhibit the photocatalysis effect of TiO2 on LLDPE. The further increase of alumina coating content reduced the UV absorption capacity of alumina‐coated TiO2 and its compatibility with the LLDPE matrix. Therefore, the best alumina coating content on the surface of TiO2 was 1.46 wt% for preparing high performance LLDPE/TiO2 composites.Highlights Alumina‐coated TiO2 with controllable coating thickness was successfully synthesized. LLDPE/alumina‐coated TiO2 has excellent UV aging resistance and mechanical properties. The photocatalytic activity and UV absorption capacity of TiO2 could be regulated. 1.46 wt% of alumina coating is the best content for high performance LLDPE/TiO2 composites.

An advanced ceramifiable organic-inorganic hybrid polysiloxane coating with superior moisture-resistant property

A ceramifiable organic-inorganic hybrid polysiloxane, prepared via a straightforward solution blending method, was successfully coated on the surface of silicon dioxide ceramic via a scrapping method. A uniform and dense lithium aluminum borosilicon (LABS) vitrified layer in situ formed on the surface of silicon dioxide ceramics was successfully prepared through liquid phase filling method to fulfill the moisture resistance requirements under high temperature cycle conditions. Effects of aluminum content on the microstructure change process and moisture resistance properties of the ceramifiable organic-inorganic hybrid polysiloxane have been systematically researched. With the increase of aluminum content, the ceramic yield of the hybrid polysiloxane and the heat loss capacity of LABS glass-ceramics increase. The crack-free and high temperature fluid vitrified layer endows the LABS glass-ceramic with excellent thermal shock resistance cycle ability, self-healing ability and moisture resistance. Results showed that the LABS vitrified coating with an aluminum-boron ratio of 1:2 presents the most appealing thermal shock cycle resistance and crack self-healing ability after 20 thermal cycles, as well as a water absorption rate of 0.3814 %. By refining the application of modified polysiloxane moisture-resistant coatings in high-temperature circulation environments, this work shed lights on the importance of in situ growth LABS vitrified coating in accelerating surface reconstruction and improving moisture resistance, incenting additional innovative breakthroughs in the LAS-based glass-ceramic materials design and fabrication within the aviation field.

Structural, optical and dielectric properties of (AZT) aluminum doped zinc titanate nano-composites

Aluminum-doped Zinc Titanate (AZT) AlxZn1-xTiO3 ( for x= 0.20,0.40,0.60,0.80) nanoparticles are synthesized through low temperature hydrothermal method and their physical properties such as structure, surface, energy gap and dielectric characteristics were investigated using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), UV-visible spectroscopy and impedance analysis. XRD analysis indicated structural transformation of tetragonal phase for samples of x = 0.20 to 0.60 and some secondary phases for x=0.80. It was found that lattice constants of the sample decrease with increasing aluminium content. The morphology of nano-composites, as evidenced by FESEM and TEM imaging, displayed the formation of nano-spheres and nano-rods. The impedance and dielectric modulus analysis for the current samples revealed their dielectric behaviour, microstructure and conduction procedure. However negative dielectric property was seen in nano-composite with x=0.60. All samples with x ranging between 0.2 to 0.8 displayed high ac-electrical conductivity at 1 MHz frequency. These samples are well suitable for charge storage capacitors and as perfect absorbers.

Characterization of Al-Substituted Ni-Zn Ferrites by XRD and FTIR Techniques

Ni0.5Zn0.5AlxFe2-xO4 (x = 0.00 to 0.50 in increments of 0.05) was prepared by the auto combustion sol-gel method, and the resulting nanopowder was subjected to calcination at three temperatures: 400, 600, and 800 °C. The structure of ferrite was characterized by XRD, and it was found that all the prepared Ni-Zn samples possess a single-phase cubic spinel structure, corresponding to the Fd-3m space group. The crystal lattice constant, a(Å), was calculated based on the resulting XRD patterns and it was found within the range of 8.312 to 8.386 Å, as the value of a(Å) decreases with increasing Al content, and increases with increasing temperature when the aluminum content (x) is constant. The Scherrer equation was used to calculate the crystalline size (D), with all samples in the range of 14.64 to 39.75 nm, and the crystalline size increases with increasing calcination temperature at a constant concentration, and increases with increasing aluminum content when the calcination temperature is constant. It was also found that the theoretical density, ρx, decreases with increasing aluminum content, and increases with increasing calcination temperature. The lengths of ionic jumps were calculated and it was found that the lengths of ionic jumps decrease with increasing Al content at a constant temperature. As FTIR spectroscopy analyzes showed the formation of Al-Ni-Zn Ferrite with a spinel structure, the increase in bond lengths in all samples leading to a decrease in the absorption frequency. The infrared absorption peaks become stronger and clearer, indicating an increase in the crystallinity of the samples, as the calcination temperature increases.

The Effect of Concentration of Aluminum on Structural, Optical, and Electrical Properties of Aluminum‐doped ZnO Nanostructures Electrochemically Deposited on Polyimide

AbstractAluminum‐doped ZnO (AZO) were successfully prepared on polyimide (PI) film using electrochemical deposition. Field emission scanning electron microscopy (FESEM) analysis revealed that as the aluminum concentration increased, the morphology of AZO nanostructures changed from pellets to nanorods. X‐ray photoelectron spectrometry (XPS) was employed to study the chemical states of undoped and Al‐doped ZnO on a polyimide substrate. The X‐ray diffraction (XRD) patterns of the PI/AZO nanostructures showed a polycrystalline wurtzite structure with a crystallographic orientation along the (002) plane. The XRD analysis also indicated that the average crystallite size decreased from 50.5 nm to 31.0 nm with increasing aluminum concentration (from 0.05 mM to 10 mM). Transmittance analysis revealed that with increasing aluminum concentration, the average optical transmittance in the visible region decreased from 90 % to 75 %. The aluminum concentration has a significant effect on the electrical properties of the samples, as shown by current‐voltage (I–V) and Hall measurements. Among the samples, the AZO/PI film prepared with 5 mM aluminum concentration exhibited the minimum electrical resistivity (4.14×10−2 Ω.cm), the highest carrier density (1.10×1021 cm−3) and the Hall mobility (5.40 cm2 V−1 s−1). We also discuss the possible mechanisms underlying these results compared to undoped ZnO films. This study contributes to the potential applications in flexible electronics and optoelectronics by demonstrating the tunability of AZO nanostructures on a flexible polyimide substrate through controlled aluminum doping.

The influence of aluminum content on thermal properties of copper-aluminum alloys: a first-principles calculation

Abstract Copper-aluminum alloy, also called aluminum bronze, is a type of host material for abradable sealing coatings. The amount of aluminum content obviously affects the properties of the coating. This research uses the density functional theory to calculate the properties of an aluminum bronze with different aluminum content. The copper-aluminum alloy model uses the model of special quasirandom structures (SQS). The elastic constant, melting point, constant pressure specific heat capacity, and thermal expansion coefficient of the copper-aluminum alloys were calculated using the quasi-harmonic approximation (QHA) method. The copper-aluminum alloys with three different nominal components were prepared using vacuum induction melting. The melting point, thermal expansion coefficient, and specific heat capacity of the copper-aluminum alloys were characterized through experiments. The results showed that the melting point of the copper-aluminum alloys decreased with an increase in aluminum content. Additionally, the coefficient of thermal expansion of the copper-aluminum alloy increased with the increase in aluminum content. Furthermore, the specific heat capacity of the copper-aluminum alloy initially increased and then reached a turning point when the β’ phase was generated. The experimental values conform well to the calculated values.

Factors affecting the expansion ratio and flow consistency of expandable foam grout for subsurface improvement

Highly porous cementitious materials have been utilized in various geotechnical applications, such as filling subsurface cavities, backfilling, and enhancing loose layers. In particular, expandable foam grout (EFG) has significant potential for cavity filling owing to its unique characteristics such as volume expansion and high flowability. Various EFG samples were prepared by mixing water, cement, aluminum powder, bentonite, and an accelerator at various ratios. Cementitious materials with various mixing ratios have different volume expansion and flowability, and each ingredient causes different impacts on their properties. This study investigated the effects of aluminum and bentonite contents on volume expansion and flowability. Expansion ratios and flow consistencies were estimated from expansion and flow tests. The results show that the expansion ratios increased with increasing aluminum content regardless of the water-cement ratio while slightly decreased with increasing bentonite content within a given range of ingredient contents. Moreover, the flow consistency increased with increasing water-cement ratio and decreasing aluminum and bentonite contents. The properties were evaluated using EFG mixtures containing relatively high bentonite contents to observe the effects of bentonite on a wide range of cementitious materials with varying bentonite contents. The expansion ratios and flow consistencies of the EFG mixtures containing relatively high bentonite contents decreased steeply with increasing bentonite content. Finally, the ingredient effects on volume expansion and flowability were discussed to design the mixture depending on its purpose.

Effect of annealing on the corrosion-fatigue strength and hot salt corrosion resistance of fine-grained titanium near-α alloy Ti-5Al-2V obtained using Rotary Swaging

The corrosion-fatigue strength in 3 % aqueous NaCl solution and the resistance against hot salt corrosion (HSC) of the fine-grained near-α alloy Ti-5Al-2V (Russian analogue of Grade 9 titanium alloy with increased aluminium content) have been studied. The properties of the Ti-5Al-2V alloy in the coarse-grained state, in the fine-grained state after cold Rotary Swaging (RS), in the partly recrystallized state and in the fully recrystallized state have been investigated. The mechanical properties of the alloy were characterised using compression tests and microhardness measurements. The effects of RS, the annealing temperature, the time on the characteristics of corrosion destruction of the surface and the composition of the products of the HSC were studied. RS was shown to increase the depth of the intergranular corrosion defects, whereas recrystallization annealing promoted an increase in the corrosion resistance of the Ti-5Al-2V titanium alloy. The parameters of the Basquin equation for the corrosion-fatigue curves for the near-α Ti-5Al-2V alloy in the coarse-grained state, in the severely strained state and after recrystallization annealing were determined for the first time. An effect of non-monotonous dependencies of the slopes of the corrosion-fatigue curves for the strained near-α Ti-5Al-2V alloy on the recrystallization annealing temperature has been observed.

Density and surface tension of liquid Al, V and their binary alloys measured by electromagnetic levitation

Both density and surface tension were systematically investigated over a wide temperature and compositional range for the liquid Al–V alloy system. The thermophysical properties were measured in an electromagnetic levitation device. A linear decrease in surface tension and density with increasing temperature was observed for every alloy composition investigated. Additionally, a decrease in density and surface tension was observed for increasing aluminum content among the different probed samples. This decrease is, a strong deviation from an ideal mixing behavior which was experienced for both properties. Different models, including variants of the well-established Butler model, were employed to better describe the compositional dependence of density and surface tension in the liquid Al–V system. The advantages and disadvantages were discussed for each model describing the measured thermophysical property data. Strong similarities were observed when comparing the mixing behavior and segregation effects of the investigated Al–V system with already established works for the liquid Al–Ti system. The results suggest that both vanadium and titanium show similar mixing behavior when alloyed with aluminum.

Effect of content on microstructure, oil painting pigment, and tensile properties of laminar composites

In this research, the Cu/Al-Al2O3 laminar composites were manufactured by pressureless infiltration casting and roll bonding processes. The effect of alumina content on microstructure, tensile properties and oil painting pigment was studied. The SEM images showed that the whiskers were aligned along rolling direction. By increasing the alumina content, the interfaces between Cu and Al-Al2O3 became wavier. The increase of whiskers improved the yield and ultimate strengths while reduced the elongation. Also, the fracture surfaces of composites indicated smaller dimples in composites with high whiskers’ content. Deeper dimples appeared near whisker cluster due to the debonding between Al and Al2O3. By increasing alumina content, the composites also experienced more oil painting penetration as a result of porosities near whiskers.

Modeling the impacts of extreme climate scenarios on soil acidity (pH and exchangeable aluminum) in Abbay River Basin, Ethiopia

The Abbay River Basin faces the looming threat of extreme climate events, including prolonged droughts and erratic rainfall patterns, which can significantly affect soil health and fertility. This study aimed to explore the influence of extreme climate conditions on soil pH and exchangeable aluminum, aiming to promote sustainable agricultural practices in Ethiopia. The Africa Soil Information Service (ASIS) provided datasets on soil pH and exchangeable aluminum. The European Copernicus Climate Change Data Store was used to download historical and future datasets of extreme climatic indices from 1980 to 2010 and 2015–2050, respectively. The Coupled Model Intercomparison Project Phase 6 model ensemble was used to predict future climate impacts under three shared socioeconomic scenarios: SSP1-2.6, SSP2-4.3, and SSP5-8.5. Data extraction, quality control, and clustering were conducted before analysis, and the model was validated for its accuracy and reliability in predicting soil parameter changes. An artificial neural network model was utilized to predict the effects of extreme climate indices on soil pH and exchangeable aluminum concentrations. The model was designed to accurately and reliably predict changes in soil parameters. This study compared the changes in soil pH and aluminum concentrations using paired t tests. The model's diagnostic results indicated a significant impact of extreme climate scenarios on soil pH and exchangeable aluminum. Extreme climate factors such as heavy precipitation and cooler night time temperatures significantly contribute to soil acidification and an increase in aluminum concentration. Under the SSP1-2.6 and SSP2-4.5 emission scenarios, soil pH levels are expected to increase by 8.38 % and 3.79 %, respectively. These changes in soil pH are expected to have significant impacts on the exchangeable aluminum content in the soil, with increases of 37 % and 5.38 %, respectively, under the same emission scenarios. However, the SSP5.8 scenario predicted a 45 % increase in exchangeable aluminum and a 9.36 % decrease in soil pH. Therefore, this study significantly enhances our understanding of the influence of climate change on soil health. The development of strategies to mitigate climate change impacts on agriculture in the region must consider the effects of extreme climate indices.

Forming high-strength and softening-resistant AlxHf0.5Mo0.5NbTa0.5TiVZr dual-phase refractory high-entropy alloys

Refractory high-entropy alloys AlxHf0.5Mo0.5NbTa0.5TiVZr with the addition of different amounts of low-density aluminum were developed to improve the strength and softening resistance at elevated temperatures. The microstructure and phase formation were investigated, and the mechanical properties and deformation behavior at various temperatures were studied. The primary dendrites consisted of body-centered cubic (Mo,Nb,Ta)-rich multicomponent phase, and the latter solidified interdendrites contained Al-(Hf,V,Zr)-rich second phase initiating from grain boundaries. With an increased aluminum content, the size of dendrites decreased, and the portion of the network-like second phase increased. The hard precipitates improved the yield strength and softening resistance but sacrificed the ductility of the alloys. At an appropriate aluminum content of x = 0.5, the Al0.5Hf0.5Mo0.5NbTa0.5TiVZr alloy showed promising softening resistance at 600 °C with a retained strength of 1240 MPa and a compressive strain of 13 %. A large number of dislocations formed a tangled dislocation forest than glided in a planar way, additionally enhancing the work hardening and improving the softening resistance. However, an excessive accumulation of dislocations at the phase boundaries caused the brittle fracture in the latter stage.