Small Grains Research Articles

The influence of Gd3+ion substitution on the microstructure and magnetic properties of NiZnMgGd ferrite

Nowadays, the rapid development and demand of electronic products have prompted electronic components to develop towards miniaturisation and even thin film, high integration and modularisation, high performance and ultra-high frequency applications. With the rapid development of electronic information technology and electronic field, NiZn ferrite material as a representative material in the soft magnetic material, through the optimisation of process technology to develop soft magnetic ferrite material with excellent performance is of great practical significance. In this study, Ni0.3Zn0.5Mg0.2GdxFe1.96-xO4 (x = 0, 0.02, 0.04, 0.06, 0.08) ferrite materials were prepared by an economical solid phase method. The XRD patterns show that NiZnMgGd ferrite materials can be successfully prepared at low doping content of Gd. However, when x ≥ 0.06, the excess Gd3+ reacts with Fe3+ and O2− in the raw material to produce the heterogeneous phase GdFeO3. From the SEM images, it can be seen that the higher the Gd content, the higher the number of small grains in the sample. A small amount of Gd3+ doping has a contributing effect on reducing the Pcv of ferrite. The quality factor of the ferrite sample with x = 0.02 is 11.92 when the frequency is 1000 kHz, which is an improvement of 100.67 % compared to the ferrite without Gd doping. From the M−H curves, Ms decreases with the increasing content of Gd replacing Fe, and NiZnMgGd ferrite is more likely to reach saturation under the action of external magnetic field. Ms, Mr and Hc indicate that NiZnMgGd ferrite material has typical soft magnetic properties.

Advancing piezoelectric properties of barium titanate ceramic through AC + DC field poling over Curie temperature

The significance of increased domain nucleation sites from smaller grain size (GS) of barium titanate (BT) ceramics on piezoelectric properties was analyzed for different types of poling, including conventional DC poling, modified DC poling, and AC plus DC poling, conducted at different poling temperatures. The AC plus DC poling conducted at 1.5 °C above the Curie temperature (T C) showed the highest piezoelectric constant (d 33) of 528 pC/N, with an average domain size of 100 nm observed after poling. The d 33 improvement was attributed to smaller domain size formation from field-induced phase transitions and homogenous distribution of point defects achieved by the AC field. Comparative analysis with larger grain BT ceramics under AC plus DC poling suggests that defects and volume fraction of grain boundaries in BT ceramics could have an effect on domain sizes.

Mitigating low-temperature hydrothermal degradation of 2 mol% yttria stabilised zirconia and of 3 mol% yttria stabilised zirconia/nickel oxide by calcium oxide co-doping and two-step sintering

Hydrothermal degradation deteriorates the fracture toughness and strength of tetragonal stabilised zirconia. The phase transformation to the monoclinic phase is particularly critical for materials with lower stabiliser content such as 2 mol% and 3 mol% yttria stabilised zirconia (2YSZ and 3YSZ). In this work, two routes in two-step sintering and co-doping with calcium oxide are analysed to mitigate the degradation. Both strategies show a reduction in average grain size of the 2YSZ while maintaining a comparable densification. The achieved smaller grains suppress the hydrothermal degradation rates. In addition, a mitigating effect beyond the reduction in grain size of YSZ is found for CaO doping. 1.6 mol% CaO co-doped 2YSZ shows less than 4% of monoclinic phase after 50 h in an autoclave with H2O at 134 °C. Pure 2YSZ contrarily reaches 100% monoclinic phase after 20 h at the same conditions. A suppression of degradation by CaO doping was also observed for the composite of nickel oxide and 3 mol% yttria stabilised zirconia. Hence, CaO co-doping can be an interesting strategy to increase resistivity against hydrothermal degradation for both biomedical and renewable energy applications. The findings further outline a route to achieve tetragonal YSZ with lower yttria contents than 2 mol%.

Incorporation of azithromycin into akermanite-monticellite nanocomposite scaffolds: Preparation, biological properties, and drug release characteristics

Bioceramics composed of calcium and magnesium silicates have garnered increasing attention for the development of porous scaffolds in bone tissue engineering (BTE). This heightened interest is primarily attributed to their remarkable bioactivity and their capacity to form strong bonds with hard tissue. Fabricating nanocomposite scaffolds is a recognized approach for improving the characteristics of scaffolds used in BTE. This research investigates the mechanical and biological properties, antibacterial activity, and drug-release characteristics of scaffolds composed of akermanite (AKT), monticellite (MON), and monticellite-akermanite (MON-AKT). These scaffolds were fabricated utilizing the space holder process. Additionally, the in vitro drug release profile and antimicrobial activity of Azithromycin (AZT)-loaded MON-AKT composite scaffolds were investigated. The findings showed that the Mon-15 wt% AKT nanocomposite scaffold had the highest density, the smallest grain and micropore sizes, and the lowest porosity. In contrast, integrating AKT into MON-based composite scaffolds resulted in materials characterized by high mechanical strength and stability within physiological environments. The MON-AKT nanocomposite scaffolds exhibited cytocompatibility and demonstrated a high level of alkaline phosphatase (ALP) activity in osteogenic studies. Furthermore, antimicrobial activity assessments revealed that the AZT-encapsulated MON-AKT composite scaffolds effectively inhibited the growth of both S. aureus and E. coli bacteria. The outcomes showed that the antibacterial efficacy of the scaffold depends on both the amount of AZT and the type of bacteria. Overall, MON-AKT/3AZT scaffolds exhibited significantly superior bacterial inhibition compared to other scaffolds, making it a promising option for treating bone tissue defects.

A new insight into the oxygen reduction reaction of the Ca3Co4O9+δ/CGO composite air electrode

The calcium cobaltite Ca3Co4O9+δ (CCO) is an emerging electrode for Solid Oxide Fuel Cells or Solid Electrolyser Cells. Thanks to a thermal expansion coefficient which is in the same range of magnitude than the commonly used electrolytes, it should lead to improved durability. However, because the material suffers of a lack of oxide ion conductivity, it has to be used in composite with an ionic conductor. Displaying good compatability with ceria, first studies were carried out on composite with Ce0.9Gd0.1O1.95 (CGO). At 700 °C, an optimal Area Specific Resistance of 0.5 Ω cm2 was obtained for a 50/50 wt.% CCO/ CGO, 21 μm thick electrode, with CCO powder prepared by a solid-state route whose synthesis method led to large grains compared to the CGO powder. Here, to increase the density of triple-phase boundaries between the gas and the two materials, a CCO powder with smaller grain size was prepared using a citrate route. For screen printed 50/50 wt.% CCO (citrate)/CGO composite electrode deposited on symmetrical cell with a CGO electrolyte, an ASR of 0.35 Ω cm2 was achieved at 700 °C, under air. To go further in the understanding of the oxygen reduction reaction, the cell was then carefully studied at variable temperatures and under variable oxygen partial pressures, combining calculation of the distribution function of relaxation times (DFRT) and complex nonlinear least squares fitting (CNLS) of impedance spectra. At 700 °C, under air, it was shown that 55 % of the ASR was due to the oxygen molecule dissociation and diffusion of atomic oxygen species at the surface of the electrode materials. It was only 37 % at 600 °C. Experiment carried out under 21 % of oxygen in helium proved that gas diffusion was a limiting step at temperature higher that 650 °C whereas the redox of CCO was limiting at lower temperature. When deposited on a commercial anode supported 2R-Cell™ half cell, the maximum power density was improved by 284 %, reaching 532 mW/cm2 at 700 °C with a 50/50 wt.% CCO (citrate)/CGO composite air electrode against 187 mW/cm2 for a 50/50 wt.% CCO (solid-state)/CGO composite air electrode at the same temperature.

Effect of cold rolling deformation on microstructure evolution and mechanical properties of spray formed Al−Zn−Mg−Cu−Cr alloys

The impact of cold rolling deformation, which was introduced after solid solution and before aging treatment, on microstructure evolution and mechanical properties of the as-extruded spray formed Al−9.8Zn−2.3Mg−1.73Cu− 0.13Cr (wt.%) alloy, was investigated. SEM, TEM, and EBSD were used to analyze the microstructures, and tensile tests were conducted to assess mechanical properties. The results indicate that the D1-T6 sample, subjected to 25% cold rolling deformation, exhibits finer grains (3.35 μm) compared to the D0-T6 sample (grain size of 4.23 μm) without cold rolling. Cold rolling refines the grains that grow in solution treatment. Due to the combined effects of finer and more dispersed precipitates, higher dislocation density and smaller grains, the yield strength and ultimate tensile strength of the D1-T6 sample can reach 663 and 737 MPa, respectively. In comparison to the as-extruded and D0-T6 samples, the yield strength of the D1-T6 sample increases by 415 and 92 MPa, respectively.

Double effects of recrystallization behavior on grain morphology evolution and mechanical properties of Al/Mg/Al composite plate by hard plate rolling

Enhancing the bonding strength, optimizing the microstructure and refining the properties represent effective strategies for the fabrication of heterogeneous composite plates. In this study, composite plates of Al/Mg/Al were fabricated through hard plate rolling (HPR) with a reduction in rolling ranging from 40 ​% to 80 ​%. The research primarily concentrates on the substrate in the influence of rolling dynamic recrystallization (DRX) behavior on the grain morphology evolution and mechanical properties of AZ31 magnesium alloy sheets during the process. The findings indicate that at a compression amount of 60 ​%, the composite plate exhibits an ultimate tensile strength (UTS), a maximum elongation (EL) of 12.5 ​%, and improved interface bonding. Comparative analysis reveals the occurrence of DRX on the Mg side, resulting in the formation of small DRXed grains being generated. With an increase in reduction, DRX is facilitated, leading to an initial rise and subsequent decline in the proportion of DRXed grains. The proliferation of fine grains hinder dislocation movement, thereby reinforcing composite plate. Moreover, an elevation in the degree of recrystallization enhances the initiation of non-basal slip and enhances the plasticity of sheet metal. This study offers valuable scientific guidance and technical assistance for the production of forming high-quality Mg–Al composite plates.

NWA 11562: A Unique Ureilite with Extreme Mg-rich Constituents

A comprehensive study of an ungrouped achondrite meteorite, North West Africa (NWA) 11562, was conducted, involving petrology, mineralogy, and mass-independent chromium isotopic composition. NWA 11562 comprises 34.9 vol% olivine, 56.1 vol% pyroxenes, 6.7 vol% Fe–Ni metal and oxides, 2.2 vol% carbon, and 0.2 vol% anhydrite. The oxygen isotopic composition (δ 18O = 6.24‰ ± 0.13‰ and Δ17O = −1.81‰ ± 0.03‰; Meteoritical Bulletin Database) and chromium isotopic compositions (ε 54Cr = −0.82 ± 0.10, 2SE) are consistent with NWA 11562 being a ureilite, and petrographic observations show features similar to those of the common ureilite group meteorites. Olivine (core: Fo99.0 ± 0.1; rim: Fo98.9 ± 0.1) and pyroxene (orthopyroxene: Mg# 99.0 ± 0.2; clinopyroxene: Mg# 99.1 ± 0.7) core compositions are more magnesian than in any previously known ureilite and lack the characteristic reduction rims of ureilites. Rounded small olivine grains within NWA 11562 indicate that the meteorite experienced impact and associated melting. Combined with the characteristic Fe/Mn ratio (3.84 ± 0.16) and Mg# (99.0 ± 0.1) of olivine cores, we suggest that NWA 11562 represents a more Mg-rich ureilite than any previously reported. NWA 11562 has a high 55Mn/52Cr ratio, and when combined with literature data, it plots on a well-defined 53Mn–53Cr isochron, providing a more accurate age, i.e., 4566.7 ± 0.8 Ma, overlapping previous work. This age may represent the result of early partial melting of the ureilite parent body.

The LTAR Cropland Common Experiment at Eastern Corn Belt.

The Eastern Corn Belt (ECB) Long-Term Agroecosystem Research (LTAR) network site is one of the most agriculturally productive areas in the United States; however, nutrient and sediment losses from this region directly contribute to water quality impairment in both the Gulf of Mexico and Lake Erie. One of the largest challenges facing agricultural production in the ECB is water management, especially under a changing climate. Shifting precipitation patterns in combination with evolving infrastructure (i.e., tile drainage, irrigation) and management (i.e., crops planted; 4R nutrient management: source, timing, rate, and placement) in response to changing climate are likely to alter water quantity and quality and agricultural productivity. Through plot- and field-scale research, the ECB Common Experiment (CE) is focused on crop, soil, and water management to support sustainable agricultural intensification, with the goal of maximizing profitability, minimizing agriculture's environmental footprint, and enhancing ecosystem services. At both spatial scales, the CE aims to examine differences in water quantity and quality between the primary prevailing crop production system in the ECB (i.e., corn [Zea mays L.]-soybean [Glycine max L.] rotation, tillage prior to corn planting, free drainage, and fertility management consistent with tri-state recommendations) and an alternative system (e.g., adding small grains into the crop rotation, cover crops, limited phosphorus fertilizer, and drainage water management). Aligning producer and stakeholders needs with research objectives and long-term data collection, the ECB CE will tackle both ongoing and newly emerging research priorities and explore the effectiveness of conservation strategies to decrease nutrient and sediment losses from agricultural land.

An IoT-Based Virtual Fence System to Control population and Deter Quelea Birds Invasion using Automated Nets

Quelea birds are small but highly intrusive birds that have become a menace in small grain farms. Previous researches has it that their extreme coordinated and destructive feeding behaviors can result in substantial crop and financials losses for small grain farmers in Zimbabwe, mostly commercial wheat farmers. Traditional methods of deterring and controlling the quelea birds’ population such as catch and consume have proven to be labour intensive, time consuming as well as costly. Some Zimbabwean wheat farmers leveraged on drone technology to scare and control the birds’ population through chemical control but these proved to be environmentally unfriendly as the chemicals might end up negatively affecting the ecosystem of the surrounding environment. The research is centered on the development of an IoT based virtual fence system to deter invasion and control quelea birds’ population using automated nets. The researcher aims to deliver an understanding of how innovative technologies such as virtual fencing, IOT and automated nets can be leveraged to address agricultural challenges caused by quelea birds to wheat farmers in Zimbabwe. The system comprises a network of linked sensors that form a virtual boundary to detect an invasion, automated nets, buzzer to deter flock and wireless network technology to send data to a central or cloud storage for future analysis and further development of the system. Ultrasonic sensors, ESP32 Microcontroller and wireless network technology were used in the development of the model. The IoT based virtual fence system to deter and control quelea birds’ population provides a cost effective, efficient and environmentally friendly solution to the quelea birds’ menace in wheat farms and ensuring food security for the country.

Influence of heat treatment and forming cycle on the precise forming of AZ31 magnesium alloy sheet

Precision forming of 3 mm thick rolled AZ31 magnesium alloy sheet at 90° results in severe cracking and a considerable rebound angle. The effects of different sheet heat treatments and changes in the forming cycle on the value of the forming angle were investigated using 90° precision forming tests. The reasons of sheet cracking were examined using tensile tests and numerical simulations. Microscopic analysis and characterization techniques such as metallographic experiments, SEM observations, and EBSD tests are used to clarify the mechanism of improvement and control of the forming angle value. The results indicate that annealing treatment exhibits high sensitivity to controlling sheet cracking, but low sensitivity to controlling rebound. Among them, after heat treatment at 250 °C+1 h, the sheet no longer cracks during forming. In incomplete annealing, the more small grains produced by recrystallization and the greater the number of dimples in the fracture, the closer the forming angle is to 90°. Full annealing can result in a small reduction in the forming angle value compared to incomplete annealing treatments. After extending the forming cycle for 1 h, the increase in the ratio of dual tensile twin boundaries and low angle grain boundaries resulted in a significant decrease in the value of the forming angle and no cracking of the sheet. The increase of recrystallized tissue on the tensile side and the increase of the KAM value led to the decrease of the forming angle value to the minimum value at 300 °C+1 h heat treatment condition.

Optimization of BaZr0.35Ti0.65O3 ferroelectric thin films on energy storage performance by adjusting annealing duration

BaZr0.35Ti0.65O3 (BZT35) ferroelectric thin films were synthesized via the sol-gel process. The phase, morphology and energy storage performance of BZT35 films of various annealing durations were studied, and the effect of annealing duration on these properties was thoroughly discussed. The size of grains in the film increases as the annealing duration prolongs, leading to an increased polarization strength. However, the breakdown field strength descends progressively with increasing annealing duration due to the increase in surface roughness. When annealed for 30 min, the film achieves the maximum polarization difference (16.1 μC/cm2) due to smaller grain size while maintaining good crystallinity, and a large breakdown field strength (3.9 MV/cm) because of its a dense structure and smooth surface. Consequently, this sample exhibits the optimal energy storage performance (Wrec = 31.54 J/cm³ and η = 91 %). The exceptional properties of BZT35 film suggest a promising application in energy storage.

The Frictional‐Viscous Transition in Experimentally Deformed Granitoid Fault Gouge

AbstractIn crustal faults dominated by granitoid gouges, the frictional‐viscous transition marks a significant change in strength constraining the lower depth limit of the seismogenic zone. Dissolution‐precipitation creep (DPC) may play an important role in initiating this transition, especially within polymineralic materials. Yet, it remains unclear to what extent DPC contributes to the weakening of granitoid gouge materials at the transition. Here we conducted sliding experiments on wet granitoid gouges to large displacement (15 mm), at an effective normal stress and pore fluid pressure of 100 MPa, at temperatures of 20–650°C, and at sliding velocities of 0.1–100 μm/s, which are relevant for earthquake nucleation. Gouge shear strengths were generally ∼75 MPa even at temperatures up to 650°C and at velocities >1 μm/s. At velocities ≤1 μm/s, strengths decreased at temperatures ≥450°C, reaching a minimum of 37 MPa at the highest temperature and lowest velocity condition. Microstructural observations showed that, as the gouges weakened, the strain localized into thin, dense, and ultrafine‐grained (≤1 μm) principal slip zones, where nanopores were located along grain contacts and contained minute biotite‐quartz‐feldspar precipitates. The stress sensitivity exponent n decreased from a large number at 20°C to ∼2.2 at 650°C at the lowest velocities. These findings suggest that high temperature, slow velocity and small grain sizes promote DPC‐accommodated granular flow over cataclastic frictional granular flow, leading to the observed weakening and strain localization. Field observations together with extrapolation suggest that DPC‐induced weakening occurs at depths of 7–20 km depending on geothermal gradient.

Theoretical investigation of threshold pressure gradient in hydrate-bearing clayey-silty sediments under combined stress and local thermal stimulation conditions

Due to the characteristics of smaller grain size and higher clay mineral content, the threshold pressure gradient (TPG) exists in multi-phase flow within hydrate-bearing clayey-silty sediments (HBCSS), which significantly affects the gas production from hydrate reservoirs. However, multi-phase flow through HBCSS relates to thermal-hydrological-mechanical coupling, leading to the understanding of TPG in HBCSS with complex pore structures and hydrate distribution is unclear. In this study, a theoretical TPG model of HBCSS is developed by considering the combined influences of effective stress, temperature increase, pore structures, hydrate saturation and its growth patterns. The proposed TPG model has been thoroughly validated using available experimental data. Moreover, the parameter sensitivity analysis is conducted based on this derived model, revealing a positive correlation between TPG and both effective stress and temperature increase. While TPG generally increases with higher hydrate saturation when other parameters are held constant, the relationship between TPG and hydrate saturation is non-monotonic. This observation suggests that TPG is impacted not only by hydrate saturation but also by other factors, including hydrate growth patterns and pore structures. The findings of this study establish a theoretical foundation for characterizing the nonlinear flow behavior during hydrate exploitation.

Selective anion exchange adsorption of molybdenum(VI) at low concentrations from an acid leached vanadium shale solution containing aluminium and phosphorus

With a decline in high-grade molybdenum reserves, the development of other types of molybdenum resources have received increasing attention. Vanadium shale is a multi-metal shale and fine-grained sedimentary rock comprising small grains and various minerals. After leaching and extracting vanadium, the solution often contains a low concentration of molybdenum. However, because of the low molybdenum concentration, many processing plants treat it as an acidic wastewater, which wastes molybdenum resources and carries the risk of environmental pollution. The leaching process of vanadium shale mostly involves high-temperature and high-pressure operations, which greatly increase the content of impurity ions such as aluminium and phosphorus in the pregnant leach solution. These impurity ions increase the difficulty in separating and recovering molybdenum. In this study, the adsorption and separation of molybdenum at leach liquor of low molybdenum concentration were investigated. The effects of different factors such as: (i) pH of feed solution, (ii) adsorption time, and (iii) presence of impurity ions, aluminium and phosphorus, on the adsorption and separation of molybdenum using five different anion-exchange resins, D201, D296, D301, D314, and D301R, were investigated. The static adsorption and desorption test results showed a molybdenum adsorption capacity of 222 mg/g at pH = 1.5 by the D301 resin. The desorption efficiency using 20% NH₄OH was 96.1%. The adsorption efficiencies of aluminium and phosphorus were 1.31% and 3.10%, respectively. This is a better choice for separating molybdenum from complex solutions. The experimental results from spectra and theoretical calculations showed that the -NH group of D301 resin was combined with the O atoms of MoO3·3H2O, Al(SO4)2−, and H2PO4− by electrostatic attraction. The binding energies of these three species were − 311 kJ/mol, −231 kJ/mol, and − 62.0 kJ/mol respectively, indicating that D301 resin preferentially adsorbed MoO3·3H2O. Based on the above results, the D301 resin can adsorb molybdenum(VI) in complex solutions under low pH conditions, and this study is expected to promote the comprehensive recovery of valuable metals from vanadium shale.

Molecular cloning and characterization of heat-responsive LcOPR1, a gene encoding oxophytodienoic acid reductase in lentil.

Improving crop plants using biotechnological implications is a promising and modern approach compared to traditional methods. High-temperature exposure to the reproductive stage induces flower abortion and declines grain filling performance, leading to smaller grain production and low yield in lentil and other legumes. Thus, cloning effective candidate genes and their implication in temperature stress tolerance in lentil (Lens culinaris Medik.) using biotechnological tools is highly demandable. The 12-oxophytodienoic acid reductases (OPRs) are flavin mononucleotide-dependent oxidoreductases with vital roles in plants. They are members of the old yellow enzyme (OYE) family. These enzymes are involved in the octadecanoid pathway, which contributes to jasmonic acid biosynthesis and is essential in plant stress responses. Lentil is one of the vital legume crops affected by the temperature fluctuations caused by global warming. Therefore, in this study, the LcOPR1 gene was successfully cloned and isolated from lentils using RT-PCR to evaluate its functional responses in lentil under heat stress. The bioinformatics analysis revealed that the full-length cDNA of LcOPR1 was 1303 bp, containing an 1134 bp open reading frames (ORFs), encoding 377 amino acids with a predicted molecular weight of 41.63 and a theoretical isoelectric point of 5.61. Bioinformatics analyses revealed that the deduced LcOPR1 possesses considerable homology with other plant 12-oxophytodienoic acid reductases (OPRs). Phylogenetic tree analysis showed that LcOPR1 has an evolutionary relationship with other OPRs in different plant species of subgroup I, containing enzymes that are not required for jasmonic acid biosynthesis. The expression analysis of LcOPR1 indicated that this gene is upregulated in response to the heat-stress condition and during recovery in lentil. This study finding might be helpful to plant breeders and biotechnologists in LcOPR1 engineering and/or plant breeding programs in revealing the biological functions of LcOPR1 in lentils and the possibility of enhancing heat stress tolerance by overexpressing LcOPR1 in lentil and other legume plants under high temperature.

Ultrafine Grain 316L Stainless Steel Manufactured by Ball Milling and Spark Plasma Sintering: Consequences on the Corrosion Resistance in Chloride Media

This paper reports experimental results concerning the corrosion of 316L austenitic stainless steels produced by ball milling and spark plasma sintering in NaCl electrolyte. Specimens with grain sizes ranging from 0.3 µm to 3 µm, without crystallographic texture, were obtained and compared with a cast that is 110 µm in grain size and an annealed reference. The potentiodynamic experiments showed that the reduction in grain size leads to a degradation of the electrochemical passivation behavior. This detrimental effect can be overcome by appropriate passivation in a HNO3 concentrated solution before consolidation. The Mott–Schottky measurements showed that the semiconducting properties of the passive layer do not vary significantly on the grain size, especially the donor density, which is responsible for the chemical passivation breakdown by chloride anions. The total electrical resistance of the layer, measured by impedance spectroscopy is always lower than the one of a cast and annealed 316L, but it slightly increases with a reduction in grain size in the ultrafine grain range. This is followed by a slight increase in the thickness of the oxide layer. The effect of chloride ions is very pronounced in terms of passivation breakdown if the powder is not passivated prior to sintering. This leads to the nucleation and growth of subsurface main pits and the formation of secondary satellite pits, especially for the smallest grain sizes. Passivation of the 316L powder before sintering has been found to be an effective way to prevent this phenomenon.

Influences of Different Selective Laser Melting Machines on the Microstructures and Mechanical Properties of Co–Cr–Mo Alloys

Dental prostheses have been fabricated using various selective laser melting (SLM) machines; however, the impact of the type of machine on the microstructure and mechanical properties of Co–Cr–Mo alloys remains unclear. In this study, we prepared samples using two SLM machines (the small M100 and mid-sized M290) with different beam spot sizes (40 and 100 µm, respectively). The microstructures and tensile properties of the heated (1150 °C for 60 min) and as-built samples were evaluated. The grain sizes of the M100 samples were smaller than those of the M290 samples due to the small beam spot size of the M100 machine. Both heated samples exhibited recrystallized equiaxed grains; however, the amount of non-recrystallized grains remaining in the M290 sample exceeded that in the M100 sample. This suggests that the M100 samples recrystallized faster than the M290 samples after heating. The elongation of the M100 samples was higher than that of the M290 samples in the as-built and heated states, owing to the smaller grain size of the M100 samples. A comparison of the M100 and M290 SLM machines indicated that the M100 was suitable for producing dental prostheses owing to its good elongation and rapid recrystallization features, which shorten its post-heat-treatment duration.

Microstructure, thermal stability and soft magnetic properties of Fe81B10P8Cu1 amorphous/nanocrystalline alloy refined by slags with low basicity

The amorphous/nanocrystalline duplex structure is stable and exhibits excellent soft magnetic properties. However, the presence of impurities inevitably impacts the performance of the products. In this work, the impact of refining slags with various basicities (R=1, 0.66, 0.5, 0.4) on the microstructure, thermal stability, and soft magnetic properties of Fe81B10P8Cu1 alloy was investigated by varying the composition ratio x:1:1 (x = 2, 3, 4, & 5) of B2O3:MnO:MgO. The utilization of refining slag with low basicity is beneficial for removing impurity, enhancing magnetic exchange interactions and reducing magnetic anisotropy in amorphous alloy, thereby improving its soft magnetic properties. Notably, when the refining slag composition of B2O3:MnO:MgO is 4:1:1, the Fe81B10P8Cu1 nanocrystalline alloy exhibits exceptional soft magnetic properties and the smallest grain size, with a Bs of 1.717 T, Hc of 3.85 A/m and an average grain size of 23.84 nm. These findings are significant for enhancing the performance of Fe-based nanocrystalline alloys.

Dust beyond the torus: revealing the mid-infrared heart of local Seyfert ESO 428-G14 with JWST/MIRI

ABSTRACT Polar dust has been discovered in a number of local active galactic nuclei (AGN), with radiation-driven torus models predicting a wind to be its main driver. However, little is known about its characteristics, spatial extent, or connection to the larger scale outflows. We present the first JWST/MIRI study aimed at imaging polar dust by zooming on to the centre of ESO 428-G14, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS) survey of local AGN. We detect extended mid-infrared (MIR) emission within 200 pc from the nucleus. This polar structure is co-linear with a radio jet and lies perpendicular to a molecular gas lane that feeds and obscures the nucleus. Its morphology bears a striking resemblance to that of gas ionized by the AGN in the narrow-line region. We demonstrate that part of this spatial correspondence is due to contamination within the JWST filter bands from strong emission lines. Correcting for the contamination, we find the morphology of the dust continuum to be more compact, though still clearly extended out to $r\approx 100 \, \rm pc$. We estimate the emitting dust has a temperature of $\sim 120\, \rm K$. Using simple models, we find that the heating of small dust grains by the radiation from the central AGN and/or radiative jet-induced shocks is responsible for the extended MIR emission. Radiation-driven dusty winds from the torus is unlikely to be important. This has important implications for scales to which AGN winds can carry dust and dense gas out into their host galaxies.