Ceramic matrix composites (CMCs) are extensively utilized in aero engines due to their high-temperature stability; however, they are prone to environmental corrosion at high temperatures, and environmental barrier coatings (EBCs) are necessary to resist oxidation and corrosion. Among various EBC materials, AlTaO4 offers high cost-effectiveness and low thermal expansion coefficients (TECs), but its resistance to SiO2 erosion and high-temperature stability remain unclear. We investigated the influences of SiO2 additions on the structures and thermal properties of AlTaO4; and AlTaO4 mixtures containing 10 wt.% SiO2 were kept at 1400 °C for 30–120 h. AlTaO4 exhibited excellent high-temperature phase stability, and SiO2 dissolved into AlTaO4 to generate a solid solution. XRD Rietveld refinement was employed to confirm the position of Si in the lattices, while SEM and EDS characterizations demonstrated the homogeneous distribution of Si, Al, and Ta elements. At 1200 °C, the TECs of SiO2-AlTaO4 (4.65 × 10−6 K−1) were close to those of SiC (4.5–5.5 × 10−6 K−1). Additionally, the addition of SiO2 could reduce TECs of AlTaO4, a feature that helped alleviate the interface thermal stress between AlTaO4 and the Si bond coat in the EBC systems. At 900 °C, the thermal conductivity was reduced by 26.9% compared to that of AlTaO4, and the lowest value was 1.65 W·m−1·K−1. Accordingly, SiO2 will enter the lattices of AlTaO4 after heat treatments at 1400 °C, and SiO2 additions will reduce the thermal conductivity and TECs of AlTaO4, which is beneficial for its EBC applications.

Early Cretaceous alkaline rhyolite in Tuohelinchang, the Great Xing’an Range: geological code for Nb–Ta elements enrichment and mineralization

ABSTRACT To meet the demand for high‐performance rare‐earth‐free permanent magnet, the Ta‐added AlNiCo permanent alloy has been prepared in this study. Effects of the Ta addition and isothermal magnetic annealing time on structure, micro‐morphology, and magnetic properties of AlNiCo alloy have been investigated. An appropriate amount of Ta addition improves the permanent magnetic performance of the AlNiCo alloy. The optimal content of Ta addition is 0.6 wt%. It is found that with increasing isothermal magnetic annealing time, ( BH ) max , H cj , and B r increase first and then decrease. The sample with the isothermal magnetic annealing time of 20 min shows the optimal permanent magnetic performance with ( BH ) max , H cj , and B r of 5.73 MGOe, 1.85 kOe, and 9.16 kGs, respectively. Ta element aggregates at the joints between adjacent α 1 phases and plays the role of separator, which reduces the magnetic interaction between adjacent α 1 phases and improves permanent magnetic performance. A modest isothermal magnetic annealing time promotes the aggregation of Ta element at the joints between adjacent α 1 phases and suppresses the formation of small α 1 phases. This is the reason for the enhancement of permanent magnetic performance.

A single‐column extraction chromatographic purification method for tungsten using the N‐benzoyl‐N‐phenylhydroxylamine (BPHA) resin was investigated in this study. This method greatly simplifies the W purification procedure, and only 10 ml of acid (5 ml 3 mol l ‐1 HCl‐0.1 mol l ‐1 HF and 5 ml 1 mol l ‐1 HF) is required to separate W from Ti, Zr, Hf, Ta and other matrix elements. The blank in the separation step was less than 0.1 ng, and the recovery of W was ~ 99%. Six independent digestion measurements of reference materials BHVO‐2, BCR‐2, RGM‐2 and JB‐2 yielded μ 182 W values (mean value with intermediate precision, 95% confidence level) of ‐10.3 ± 4.0 ( n = 6, 2 s )，‐1.2 ± 5.3 ( n = 6, 2 s )，‐1.4 ± 4.4 ( n = 6, 2 s ) and 0.6 ± 3.8 ( n = 6, 2 s ), respectively, which are in good agreement with the previously reported values.

This article presents a review of the composition optimization progress of nickel-based single crystal (SC) superalloy design in recent years in order to obtain better high-temperature performance for the development of the aviation industry. The influence of alloying elements on the creep resistance, microstructure characteristics, oxidation resistance, castability, density, and cost of superalloys is analyzed and discussed. In order to obtain better high-temperature performance, the content of refractory elements (Ta + Re + W + Mo) and Co was increased gradually. The addition of Ru was added in the fourth-generation nickel-based SC superalloy to stabilize the microstructures and suppress the precipitation of the topologically close-packed (TCP) phase. However, the content of the antioxidant element Cr significantly decreased, while the synergistic effect of Al, Cr, and Ta received more attention. Therefore, synergistic effects should also receive more attention to meet the practical needs of reducing the content of refractory elements to reduce costs and density in future single crystal alloy designs without compromising critical performance.

In order to reveal the genesis and tectonic background of the mafic rocks in the South Altyn area, the diagenetic age and geochemical characteristics of diabase gabbro in the Saitama area were discussed by using LA-ICP-MS zircon dating and geochemical analysis. The diabase gabbro in the Saitama area of the South Altyn region is 206Pb/238U and has an age of 423 Ma. The SiO2 content of diabase gabbro ranged from 48.28 to 54.53%, and the average value was 50.76%. The variation range of Mg# value was 25.80 ~ 57.97, and the average value was 45.17. The content of K2O + Na2O varied between 2.46 and 7.63%, and the average value was 4.71%, which belonged to the alkaline series. It enriches large ionic lithophilic elements (LILE) and light rare earth elements such as Rb, Ba, Th, U, K, La, and Ce, and loses high field strength elements (HFSE) such as Nb, Ta, Ti and heavy rare earth elements. The study of lithogenesis shows that the mantle source magma of diabase gabbro in the Saitama area has the addition of crustal materials, and the mode of action should be the mixing of the source area, and the addition of crustal materials may be related to the dismantling and subsidence of the thickened lithosphere after the deep subduction of the South Altyn Basin in the middle and late Ordovician. The occurrence of mafic–ultramafic rocks around 423 Ma in the Saitama area may imply the transition of the tectonic system from extrusion to extension.

Although Ti–6Al–4V stands out as one of the best in biomedical, automotive, and aerospace applications due to its low density and higher corrosion resistance, the toxicity associated with Al and V elements is shifting the usage of Ti-based alloys with reduced toxic content but with more biocompatible elements (Zr, Ta, and Nb). Despite the advancements in the era of micromachining, machining these alloys with traditional machining methods is highly tedious. The present research evaluates the micromachining performance of the TNTZ (Ti–29Nb–13Ta–4.6Zr) alloy employing a tungsten carbide electrode using the µ-EDM (micro-electro-discharge-machining). The primary input parameters examined are voltage (80–130 V) and capacitance (10–400nF), with a feed rate of 0.09 mm/s during the experiments. The output responses assessed include VMR, OC, CErr, and SFR. Meanwhile, due to the complexity of the µ-EDM process, it presents significant challenges in predicting performance across different machining settings. The interactions between key process parameters, such as C and V, amplify their parametric sensitivity, making conventional simulation approaches inadequate for accurately modeling these interdependencies. To address these challenges, the latter part of this study explores machine learning techniques, particularly Multiple linear regressor (MLR), decision tree regressor (DTR), and artificial neural network (ANN) for predictive accuracy. The models are evaluated using two key performance metrics: normalized root mean squared error (NRMSE) and R-squared (R2). The ANN demonstrated superior capability in handling experimental variability based on the prediction results. It has the highest R2 of 0.99, the lowest NRMSE of 0.0245, and the percentage of prediction error is less than 5%.

Ti-2Al-9.2Mo-2Fe (2A2F) alloy is a low-cost β-Ti alloy in which the expensive β-stabilizing elements (Ta, Nb, W, Ni) are replaced with relatively inexpensive Mo and Fe for use in low-cost applications in various industries. The 2A2F alloy exhibits excellent mechanical properties such as high specific strength and low elastic modulus compared to conventional steel alloys but is prone to brittleness owing to the formation of the ω phase when heat-treated at relatively low temperatures. Therefore, an appropriate aging treatment should be performed to control the precipitation of the isothermal ω phase and secondary α phase. This study aims to derive the appropriate aging-treatment conditions following a solution treatment at 790 °C for 1 h, which is below the β-transus temperature of 815 °C. The aging treatments are conducted at holding temperatures in the range of 450-600 °C and holding times between 1 and 18 h. At relatively low aging temperatures of 450 °C and 500 °C, the precipitation of the isothermal ω phase resulted in significantly high hardness and compressive strength. As the aging temperature and holding time increased, the ω phase gradually transformed into the secondary α phase, leading to a balanced combination of strength and ductility. However, at excessively high aging temperatures and prolonged durations, excessive precipitation and growth of secondary α phases occurred, which caused a reduction in hardness and compressive strength, accompanied by an increase in ductility. In this study, the effects of precipitation evolution on mechanical properties such as tensile strength and hardness under various heat treatment conditions were comparatively analyzed.

Uranium-containing high-entropy alloys (HEAs) exhibit great potential as a novel energetic structural material, attributed to their excellent performance in impact energy release, superior mechanical properties, and high density. This study investigates the effects of Ta content on the phase stability, lattice constant, density, elastic constants, polycrystalline moduli, and electronic structure of (UNbMoHf)54−xTax high-entropy alloys (where x = 2, 6, 10, 14, 18), utilizing a combination of density functional theory (DFT) calculations and the special quasi-random structure (SQS) approach. Our findings confirm that these alloys maintain stable body-centered cubic structures, as evidenced by atomic radius difference and valence electron concentration evaluations. Analysis of elastic modulus, Cauchy pressure, and Vickers hardness indicates that Ta incorporation enhances mechanical properties and increases the anisotropy of these alloys. Furthermore, investigations into the electronic structure reveal that adding Ta reduces metallic character while increasing covalent characteristics, enhancing the contribution of Ta’s d-orbitals to the total density of states and intensifying covalent bonding interactions between Ta and other elements such as Nb, Mo, and U. These findings provide theoretical guidance for the design of high-performance UNbMoHfTa HEAs with tailored properties.

High-performance powder metallurgy (PM) superalloy turbine disk is crucial to the development of the new generation of aero-engines with a high thrust-to-weight ratio. In this study, the particle size distribution, sphericity, microstructure, defects and dendritic segregation of a newly designed FGH4108 superalloy powder were characterized, and the solidification thermodynamic parameters were calculated. The results indicate that the particle size distribution of powder is uniform and normal distribution, and the sphericity is high. As the particle size decreases, the SDAS decreases due to the increase in cooling rate. The powder microstructure transforms from dendrite to cellular structure, leading to refined microstructure. The cooling rate plays a dominant role among the influencing factors of powder structure. The powder with a particle size below 38 μm has a dense structure and essentially no defects. The powder with a particle size exceeding 38 μm contains satellite powder and hollow powder, which increase with the growth of particle size. Nano-scale dendritic segregation is present in FGH4108 powder. Elements such as W, Cr, Co, Ni, and Al are enriched in the dendrite axis, while elements like Hf, Ta, Nb, Ti, and Mo are enriched in the interdendritic region. As the particle size decreases, the degree of dendritic segregation decreases. In summary, it is recommended to select powders with a particle size range of 38–63 μm in the subsequent production process.

The Wubaduolai copper deposit, a newly discovered porphyry-type deposit located in the western section of the Gangdese metallogenic belt, shows great potential for mineralization. Investigating the ore-bearing potentiality of the adakitic granite in this area is crucial for identifying concealed ore bodies and assessing the metallogenic potential. This paper presents the zircon U-Pb dating, Hf isotope analysis, and whole-rock major and trace geochemical analysis of the plutons in the Wubaduolai mining area. The results indicate that the zircon U-Pb concordia age of the monzogranite is 15.7 ± 0.1 Ma, while the granodiorite porphyry has a concordia age of 15.9 ± 0.2 Ma, both corresponding to a Miocene diagenesis. The geochemical data show that both plutons belong to the high-K calc-alkaline series, characterized by a relative enrichment of large-ion lithophile elements (K, Rb, Ba, and Sr) and a depletion of high-field-strength elements (Nb, Ta, and Ti). Both plutons are characterized by low Y, low Yb, and high Sr/Y values, displaying the typical geochemical characteristics of adakites. Their mineral composition is similar to that of adakite. The εHf(t) values of the monzogranite and granodiorite porphyry range from −5.34 to −2.3 and −5.2 to −3.43, respectively, with two-stage model ages (TDM2) of 1246–1441 Ma and 1318–1432 Ma. Based on the regional data and this study, the plutons in the Wubaduolai mining area formed in a post-collision setting following the India–Asia continental collision. The magma source is identified as the partial melting of a thickened, newly formed lower crust. The above characteristics are consistent with the diagenetic and metallogenic ages, magma source, and dynamic backgrounds of the typical regional deposits.

Abstract Cr and Cr(Ta) coatings were deposited on the surface of gun steel by using magnetron sputtering technology. The two coatings were analyzed for their morphological features, phase composition, hardness, and elasticity modulus using scanning electron microscopy (SEM), X-ray diffraction (XRD), and nanoindentation techniques. The wear resistance differences between the two coatings were evaluated using a friction and wear testing machine. The results showed that the Cr coating has a typical columnar crystal structure, while the Cr(Ta) coating has an equiaxed crystal structure. Both the Cr and Cr(Ta) coatings show preferred orientation on the Cr(110) crystal plane. After analyzing the coefficient of friction (COF) and the morphology of the wear tracks, it was found that the Cr(Ta) coating exhibits superior wear resistance compared to the Cr coating. This demonstrates that the incorporation of the Ta element enhances the wear resistance of the Cr coating.

Abstract In the present study, the role of elements such as Ta (tantalum), W (tungsten) and Mo (molybdenum) in the alloys as well as standard elements such as Cr (chromium), Fe (iron) and Ni (nickel), was analyzed in more detail by using molecular dynamics study (MD) based density functional theory (DFT) for recently newly produced WxTayCr5Ni5Fe5Mo5 alloys. It was observed that the increase in the Ta/W ratio causes a decrease in radiation shielding feature since there is agglomeration of Ta elements among the W elements, as well as Ta is the less dense element. It is seen that this Ta agglomeration occurs when W elements are separated from each other by Mo, showing thermal stability. This prevents W elements from agglomerating. For this reason, the first solidification in the alloy in the cooling phase starts with Ta atoms. It was observed that the W-Mo duo in the nanostructure plays a mixer role in the alloy. Another feature in this simulation is that, since the agglomeration of W elements in the absence of the Ta element has a heterogeneous effect in the alloys, a strain softening structure is seen in mechanical property and thus the remainder of the material consists of low-density elements. So, the radiation shielding feature is negatively affected. W-Mo duo creates the homogenous dispersing role of W elements. This situation leads to the emergence of a new definition in materials science. This nano mixer effect, which belongs to the W-Mo duo, was described for the first time in this study. It is observed that the mixing effect of W-Mo duo can be effective up to the melting temperature of Mo. Also the effect of Pt-W duo, which creates the best homogeneity effect among transition metals, was also examined. The nano mixer effect of the Pt-W duo was found to be more effective than the Mo-W duo.

Granodiorite, medium grain granite gneiss, medium grain banded gneiss with pegmatite intrusion, comprise the Basement Complex rocks of Chessu. The primary geological structures that emerge from the Pan Africa ductile and brittle deformation stages are fold, strike slip fault, dextral shear plane and fractures in Chessu and environs. Tin and tantalum containing pegmatites are found in the main E-W and NE-SW fault. Field observation demonstrate NE-SW, NNE-SSW and N-S structural trend with dipping values ranging between 19-52 in accordance with data collected, displayed on rose plots and equally supported by lineaments. In terms of petrography, medium grained banded gneiss, medium grain granite gneiss and granodiorite all contain quartz, plagioclase, biotite and muscovite. Pegmatite contains muscovite, biotite, quartz and orthoclase among other opaque minerals. The protoliths of the gneisses, which may be from granite are revealed by the geochemical data used on Middlemost plots (Na2O + K2O vs SiO2), which suggest that the rocks are members of the granitoid family. The Harker’s variation Plots of SiO2 vs Na2O, K2O, CaO, MgO, TiO2, P2O5, reveals intense alteration and contamination during fractionation of the rock, as displayed by the scattered/non-linear trends. The primitive mantle (spider plot) indicates the depletion of some compatible less mobile elements (Ti, Y, Zr and Sr) and enrichment of incompatible elements (Th, Rb, Nb, Ta, Sr and Pb), which reveal the mineralization potential in these incompatible elements. The enriched elements Th, Nb, Ta and Pb are used as the pathfinder elements for Tin and Tantalum mineralization in Chessu area. The deformation processes and structures created in the latter phase of Pan Africa Orogenic event resulted in the pegmatite emplacement, this could infer a connection between the mineralizing fluid and the rocks.

In the present research the structure and phase composition of nanolaminate ARC-PVD ZrTaN/ZrTiCuN coatings have been investigated. Raman spectroscopy, scanning electron microscopy (SEM) with microanalysis (EDX), X-ray diffraction analysis were used to study the surface morphology, chemical composition and its distribution. The lattice parameters of the phases detected in the coatings by XRD differ from the literature values and the reason for such deviations can be both the presence of macrostrains in the coatings and the replacement of zirconium by other elements (Ta, Ti, Cu) in the sub-lattice cells of the above-mentioned phases.

Six multi‐principal‐element (“high‐entropy”) Co–Fe–Ni‐based superalloys are produced with 1) various ratios of Co, Fe, and Ni; 2) a constant concentration (13 at%) of γ′ formers (sum of Al, Ti, V, Nb, and/or Ta) without W; and 3) up to 8% Cr. The role of different ratios of γ′ to γ formers on stability of the γ + γ′ microstructure is investigated via calorimetry and metallographic imaging after aging for 1000 h at 850 °C, culminating in a W‐free superalloy with equiatomic concentrations of γ‐ and γ′‐forming elements: (Co 0.33 Fe 0.33 Ni 0.33 ) 87 (Al 0.33 Ti 0.33 V 0.33 ) 13 . This new alloy displays a γ/γ′ microstructure with γ′ volume fraction of ≈40% and no additional phases. Herein, a stable, continuous γ + γ′ phase field is found when transitioning from W‐free Co‐based superalloys to this new equiatomic (CoFeNi) 87 (AlTiV) 13 composition. An intermediate Co–Ni–Fe superalloy with high Cr content (31Co–30Ni–18Fe–8Cr–5Al–3V–2Ti–1.5Nb–1.5Ta, at%) shows a higher solvus temperature and larger γ′ volume fraction, consistent with the addition of two refractory elements (Nb and Ta).

Titanium and its alloys could have good biocompatibility, suitable levels of strength, fracture toughness, fatigue resistance and low elastic modulus, which are requirements for metallic materials used as biomaterials. Implants of commercially available Ti alloys show excessive levels of stiffness that cause stress shielding and often lead to bone resorption and failure. For better biomechanical performance, it is necessary to redesign biomaterials with lower elastic modulus. Alloying Ti with β-stabilizing elements (Ta, Mo, Nb) allows obtaining alloys with Young´s modulus closer to that of bone (10-30 GPa), minimizing the tendency for stress shielding and bone resorption. A combinatorial method, based on variable composition laser deposition, has been used for synthesizing alloys with a gradient of composition along a single clad track and scanning for the most interesting compositions. This study reports results on laser synthesis of alloys in the Ti-5Mo-xNb system, in search for compositions with microstructure and properties optimized for use as biomaterials. The alloys were then characterized in composition and microstructure by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The mechanical properties were assessed using depth-sensing ultramicroindentation tests. Their microstructures consist of the orthorhombic α’ phase with martensitic morphology, and untransformed β. The alloys indentation hardness increased with the Nb content from 2.79 ± 0.02 GPa to 3.7 ± 0.8 GPa, due to solid solution strengthening. The same trend was observed in the elastic moduli that increased from 38.8 ± 8.1 GPa to 76 ± 13 GPa, and in addition the H/E ratio was greater than 0.04 for all samples which indicates good wear resistance. Despite being dual phase (α’+β) all compositions present elastic modulus that are considerably lower than those of commercial Ti alloys currently used (above 100 GPa).

This study evaluated concentrations of potentially toxic elements (PTEs)-As, Sb, Co, Cr, Zn, U, and Th-in sediment cores from the Jundiai and Taiaçupeba reservoirs in the Upper Tiete Water Basin, Sao Paulo, Brazil. These reservoirs are vital for supplying water to the São Paulo metropolitan area but face risks from agricultural and industrial activities. The research aimed to determine whether PTE enrichment in sediments is due to natural or anthropogenic factors, assess the influence of sediment geochemistry and grain size, and evaluate risks to public health and biota. Granulometric analysis and enrichment factors were used to interpret the results, with As, Cr, and Zn compared to sediment quality guidelines. Significant Zn contamination was found in the Taiaçupeba reservoir, exceeding the Probable Effects Level (PEL), suggesting mining-related contamination. This highlights the need for further research on Zn's spatial distribution, ecological risks, and bioavailability in the Taiaçupeba reservoir. Conversely, Sb, Co, Cr, U, and Th were linked to natural processes. Arsenic showed a local geologic anomaly in both reservoirs. This research emphasizes the importance of geochemistry as a critical tool for interpreting PTEs in trace element environmental monitoring. Geochemical parameters, including Hf, Ta, Sc, and K, and rare earth elements, were essential for understanding sedimentary dynamics and anthropogenic impacts. This approach enhances the effectiveness of PTE impact assessments and can be applied to other dam reservoirs worldwide.

Abstract Cu-based materials consisting of immiscible elements have been paid much attention due to their high strength and high conductivity. The amorphous layers between Cu and strengthening phases formed through severe deformation play a crucial role in the improvement of properties. In this study, structure evolution, thermal stability of Cu100−xTax (x = 10, 30, 50, and 70 at%) amorphous alloys and diffusion behaviors of alloys were studied by ab initio molecular dynamics (AIMD) simulations. With the Ta concentration rising, the number increase of Cu-Ta and Ta-Ta bonds results in the increase of volume for Cu-Ta amorphous alloys. Ta tends to be soluble in Cu clusters for Cu-rich amorphous alloys while Cu tends to be soluble in Ta clusters for relatively Ta-rich ones. According to energy evolution, the thermal stability of amorphous alloys decreases and then increases as Ta concentration increases. Compared with Cu element, the diffusion of Ta is significantly limited. The differences in thermal stability between Cu-Ta amorphous alloys and diffusion of Cu and Ta elements result in the formation of Ta-rich amorphous alloys after non-equilibrium fabricating. These results could substantively contribute to the development of Cu-based materials and understanding of the interface characteristic of immiscible alloys.

Designing stronger γ′-hardened NiCoCr medium entropy alloys