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Abstract Hydrological connectivity is crucial for understanding water-ecosystem dynamics, as it serves as a key link between different landscape units. However, the variability of hydrological connectivity in Central Asia remains unexplored, which poses challenges to a comprehensive understanding of ecohydrological processes. This study investigates the spatiotemporal patterns and driving mechanisms of hydrological connectivity in the Tarim River Basin (TRB), Central Asia, from 1990 to 2020, employing a novel approach that integrates remote sensing and reanalysis data. The results indicate an increasing trend in the hydrological connectivity index (HCI), with approximately 60% of the TRB exhibiting significant increases. Climate change exerts the greatest direct (0.59) and total (0.64) effects on HCI, with potential evapotranspiration (19.2%) and temperature (12.6%) being the dominant factors. In mountainous regions, climate change (0.65) is the primary driver, while human activities have a greater impact in the plains (−0.27). These findings offer a new framework for studying ecohydrological processes in arid regions.

A powder-metallurgy MoNbTaTiV refractory high-entropy alloy synthesized by mechanical alloying (MA) and spark plasma sintering was subjected to hot deformations at different temperatures and strain rates. The microstructural morphologies were characterized, and component element segregation was elucidated. With grain refinement and lattice strain increase, the large inhomogeneous milled powder became refined and homogeneous after the MA. Component element segregation was observed at relatively low deformation temperatures and high strain rates. As the deformation temperature increased and the strain rate decreased, the segregation gradually disappeared, which was attributed to dislocation movement.

The Ti2AlNb alloy, solution-treated at 1070 °C, underwent hot rolling at 960 °C with different thickness reductions to investigate the synergistic effects of the O phase and B2 phase and their impact on its properties. The results reveal that after solution treatment, the Ti2AlNb alloy consists of nearly spherical O, lath O, and B2 matrix at 30% and 50% thickness reductions during hot rolling. However, at a 70% thickness reduction, the alloy exhibits spherical O, worm-like O, and a continuously distributed B2 phase. The α2 phase formed during solution treatment decomposes during hot rolling. As the thickness reduction increases from 30% to 70%, the O phase content initially rises and then declines, accompanied by an increase in the average dimension of the O phase from 0.25 ± 0.16 μm to 0.36 ± 0.18 μm. Additionally, the B2 phase in the alloy undergoes dynamic recrystallization (DRX) during hot rolling, coinciding with the growth and spheroidization of the O phase. With an increase in the thickness reduction during hot rolling, the elongation of the alloy increases from 5.9% at 30% reduction to 12.47% at 70% reduction. Meanwhile, the ultimate tensile strength reaches its peak value of 1092.2 MPa at 30% reduction, decreases to 936 MPa at 50%, and then increases to 970 MPa at 70%. The tensile strength of the alloy improves due to the interaction and accumulation of dislocations at the phase interface. The continuous distribution of the B2 matrix, dislocation movement, rotation of the O phase, DRX of the B2 phase, and interface slip all contribute to enhanced ductility. Furthermore, the fracture behavior of the Ti2AlNb alloys under various hot rolling conditions was elucidated.

Al-Zn-Mg-Cu aluminum alloy wires were annealed at 404 °C and then cooled at 10–100 °C/h. On the basis of the cooling speed of 10 °C/h, a second stage of 232 °C annealing was added and held for 4–8 h. The differences in grain organization, grain boundary precipitation phase, electrical conductivity, mechanical properties and intergranular corrosion properties of Al-Zn-Mg-Cu aluminum alloy wires with different annealing processes were comparatively investigated by using electron backscatter diffraction (EBSD) technique, transmission electron microscope (TEM), electronic tensile tester, conductivity meter. It is found that the grain size of Al-Zn-Mg-Cu wire after different annealing processes has not grown significantly, and the grain orientation has not changed obviously. As the cooling speed decreased from 100 °C/h to 10 °C/h, the precipitated η phase continued to merge and grow, from chain distribution to independent distribution, and the Cu element in η phase increase. The Cu content of η phase increases to 14.7 wt% by adding a second annealing stage. The conductivity of the alloy increases to 48.6 %IACS and the tensile strength is reduced to 168 MPa. In addition, the maximum corrosion depth of the alloy is reduced to 16 μm. It shows good mechanical properties and excellent corrosion resistance.

Coarsening of the γ′ phases in Inconel 617 superalloy during long-term service can cause degradation of mechanical properties. In this study, we investigated the microstructural modulation of γ′ phases in γ matrix by heat treatments to obtain two different initial microstructures of the alloy, and studied their influence on the microstructural evolution and mechanical properties during subsequent service. The solution + sub-solution heat-treated (SST) alloys had not only better short-term mechanical property, but also excellent long-term thermo-mechanical property stability compared to the standard solution heat-treated (ST) alloys. This was mainly attributed to the large number of M23C6 carbides precipitated in the microstructure after sub-solution heat treatment. M23C6 carbides was found to solubilize Al and Ti elements and decrease the solubility of Al and Ti elements in matrix around M23C6 carbides, thus significantly inhibiting the coarsening of γ′ phases during long-term aging. The γ′ coarsening rate of ST alloys is approximately 10 times that of SST alloys. Moreover, we investigated the evolution of deformation mechanisms with γ′ phases coarsening during long-term aging. By analyzing the deformation mechanism, the optimal γ′ phases diameter precipitation range was roughly determined, which has important guiding significance for the subsequent upgrading and optimization of Inconel 617 superalloy.

Abstract The copper (Cu)-catalyzed electrochemical CO2 reduction provides a route for the synthesis of multicarbon (C2+) products. However, the thermodynamically favorable Cu surface (i.e. Cu(111)) energetically favors single-carbon production, leading to low energy efficiency and low production rates for C2+ products. Here we introduce in situ copper faceting from electrochemical reduction to enable preferential exposure of Cu(100) facets. During the precatalyst evolution, a phosphate ligand slows the reduction of Cu and assists the generation and co-adsorption of CO and hydroxide ions, steering the surface reconstruction to Cu (100). The resulting Cu catalyst enables current densities of > 500 mA cm−2 and Faradaic efficiencies of >83% towards C2+ products from both CO2 reduction and CO reduction. When run at 500 mA cm−2 for 150 hours, the catalyst maintains a 37% full-cell energy efficiency and a 95% single-pass carbon efficiency throughout.

Highlights Representative methods for calculating the depth of discharge of different Zn anodes are introduced. Recent advances of aqueous Zn metal batteries with high Zn utilization are reviewed and categorized according to Zn anodes with different structures. The working mechanism of anode-free aqueous Zn metal batteries is introduced in detail, and different modification strategies for anode-free aqueous Zn metal batteries are summarized.

Nb-lean Cu–Cr–Nb alloys have been widely applied in electrical industries as the structural conductive material owing to their excellent combination of the mechanical and electrical properties at room temperature. In this work, the influence of temperature during fast sintering and post-heat treatment strategies on the precipitate evolution and room temperature mechanical properties of the Cu–3Cr-0.5Nb (wt.%) alloy was investigated. The increasing sintering temperature will improve the density and mechanical properties of the alloy without any obvious grain growth during this non-equilibrium process, while the post-aging at lower and higher temperatures can effectively control the formation and coarsening process of the Cr-based precipitates. Systematic characterization was then conducted on the microstructural evolution, especially the altering precipitates’ size and distribution, in the alloy at both as-sintered and the aged conditions, which is correlated to its room temperature tensile properties. Lower aging temperature will induce the nucleation of the new Cr2Nb precipitates without causing a significant coarsening of the existing precipitates like aging at higher temperature. Therefore, the low-temp. aged sample exhibits the highest tensile strength and elongation due to the enhanced Orowan strengthening mechanism induced by its unique precipitate microstructure.

Deep learning techniques are increasingly applied to point cloud semantic segmentation, where single-modal point cloud often suffers from accuracy-limiting confusion phenomena. Moreover, some networks with image and LiDAR data lack an efficient fusion mechanism, and the occlusion of images may do harm to the segmentation accuracy of a point cloud. To overcome the above issues, we propose the integration of multi-modal data to enhance network performance, addressing the shortcomings of existing feature-fusion strategies that neglect crucial information and struggle with matching modal features effectively. This paper introduces the Multi-View Guided Point Cloud Semantic Segmentation Model (MVG-Net), which extracts multi-scale and multi-level features and contextual data from urban aerial images and LiDAR, and then employs a multi-view image feature-aggregation module to capture highly correlated texture information with the spatial and channel attentions of point-wise image features. Additionally, it incorporates a fusion module that uses image features to instruct point cloud features for stressing key information. We present a new dataset, WK2020, which combines multi-view oblique aerial images with LiDAR point cloud to validate segmentation efficacy. Our method demonstrates superior performance, especially in building segmentation, achieving an F1 score of 94.6% on the Vaihingen Dataset—the highest among the methods evaluated. Furthermore, MVG-Net surpasses other networks tested on the WK2020 Dataset. Compared to backbone network for single point modality, our model achieves overall accuracy improvement of 5.08%, average F1 score advancement of 6.87%, and mean Intersection over Union (mIoU) betterment of 7.9%.

Oxide dispersion strengthened tungsten (ODS-W) alloy was prepared by chemical method, conventional sintering and hot-rolling method, which breaks through the research bottleneck of preparing tungsten alloys with excellent comprehensive mechanical properties. More specifically, it can exhibit ultrahigh strength and superior toughness when tested at 200°C. In addition, the nil ductility temperature (NDT) can also dramatically decrease to 100–150°C. The bimodal structure formed by the uneven distribution of yttria and the lamellar structure formed by hot rolling in this ODS-W alloy provide a feasible way to develop other engineering materials with ultra-high strength and ductility.

Natrium superionic conductor (NASICON)-type phosphates have aroused a great interest as cathode materials for sodium-ion batteries (SIBs) by virtue of their stable 3-dimensional frameworks, flexible molecular formula tunability, and superior ionic conductivity. Nevertheless, the intrinsic low electronic conductivity and relatively low theoretical specific capacity place obstacles in their way toward achieving higher electrochemical performance. In addition, only 2-electron reactions in most NASICON cathodes and poor reversibility of high-voltage redox couples severely limit their energy density. To address the above tough issues, an in-depth understanding of transition metal selection, elements ratio optimization, and Na-storage mechanism is of paramount importance. Here, this mini review summarizes the latest progresses on the NASICON-type phosphate cathodes for SIBs from the perspective of redox couple modulation. NASICON cathodes featuring high operating voltage and multielectron reactions are discussed in detail. Finally, the remaining challenges and personal outlooks based on redox couple regulation are put forward, shedding light on the designing rules for high-energy and long-durability NASICON-type phosphate cathodes for SIBs in the future.

Climate change is exacerbating the occurrence of compound droughts and heatwaves (CDHWs), which pose a serious threat to human health and socio-economic development. Using daily maximum temperature (Tmax) and monthly self-calibrating Palmer drought severity index (sc-PDSI) dataset, the evolution patterns of CDHWs and compound wet-heatwave events, the dominant drivers and the relative contributions of droughts and heatwaves in the drylands and humid areas from 1961 to 2020 were compared and analyzed. The results show that the CDHWs are stronger in drylands than in humid areas, the growth rate of CDHWs in drylands was almost twice that of the humid areas, the CDHWs are greater than the multi-year average intensity of compound wet-heatwave events by up to 2.4 times. Moreover, CDHWs has increased significantly from the past period (1961–1990) to the recent warm period (1991–2020), and the heatwave threshold has increased by about 5 °C. In most drylands, the contribution of heatwaves to CDHWs dominates, whereas in humid areas, the droughts contribution to CDHWs does. The compounding effects of droughts and heatwaves may exacerbate the severity of CDHWs regionally and are most pronounced in drylands, taking into account optimal lags. The study findings could provide scientific and technological support to actively address global climate change risks.

Ultra-thick, dense alloy-type anodes are promising for achieving large areal and volumetric performance in potassium-ion batteries (PIBs), but severe volume expansion as well as sluggish ion and electron diffusion kinetics heavily impede their widespread application. Herein, we design highly dense (3.1 ​g ​cm−3) Ti3C2Tx MXene and graphene dual-encapsulated nano-Sb monolith architectures (HD-Sb@Ti3C2Tx-G) with high-conductivity elastic networks (1560 ​S ​m−1) and compact dually encapsulated structures, which exhibit a large volumetric capacity of 1780.2 ​mAh cm−3 (gravimetric capacity: 565.0 ​mAh g−1), a long-term stable lifespan of 500 cycles with 82% retention, and a large areal capacity of 8.6 ​mAh cm−2 (loading: 31 ​mg ​cm−2) in PIBs. Using ex-situ SEM, in-situ TEM, kinetic investigations, and theoretical calculations, we reveal that the excellent areal and volumetric performance mechanism stems from the three dimensional (3D) high-conductivity elastic networks and the dual-encapsulated Sb architecture of Ti3C2Tx and graphene; these effectively mitigate against volume expansion and the pulverization of Sb, offering good electrolyte penetration and rapid ionic/electronic transmission. Ti3C2Tx also decreases the K+ diffusion energy barrier, and the ultra-thick compact electrode ensures volumetric and areal performance. These findings provide a feasible strategy for fabricating ultra-thick, dense alloy-type electrodes to achieve high areal and volumetric capacity energy storage via highly-dense, dual-encapsulated architectures with conductive elastic networks.

The strengthening of micro-sized phases and nano-precipitates to the Al–Mg2Si–Cu(–Ni) alloys was studied at 25 °C and 350 °C. In the Al–15%Mg2Si–5%Cu alloy, lots of nano-precipitates (θ″, θ′, σ and Q′ precursor) are formed with the dissolution of Cu-rich phases after heat treatment. The high number density of nano-precipitates contributes to the high strength of alloy (357 MPa) at 25 °C. For the Al–15%Mg2Si–5%Cu–1%Ni alloy, more micro-sized Cu/Ni-rich phases are retained and fewer nano-precipitates (θ″, θ′, σ and S phase) are formed after heat treatment. The existence of high-temperature stable micro-sized Cu/Ni-rich phases produce an enhanced strengthening effect (109 MPa) to the alloy at 350 °C, compared to that of Al–15%Mg2Si–5%Cu alloy (82 MPa).

Wrought nickel alloys are widely applied in hot static components for aero-engines, acquisition for the underlying mechanism of microstructural evolutions controlling mechanical degradation during elevated-temperature exposure is fundamentally vital to processing optimization as well as serving life prediction. In present work, the differential hot tensile characteristics during 500–2000 h exposure at 650 °C of wrought Inconel 718 alloy having specific microstructures designed via different processing routes were comparatively evaluated. The experimental results showed the static mechanical stability of Inconel 718 alloy was predominantly tailored by the complicated interaction of γ-matrix grain configuration and δ precipitation on grain boundaries (GBs). It mainly involved continuous GB-δ precipitation during the 500–2000 h exposure at 650 °C, which played opposite roles in homogeneous or heterogeneous grain configurations. GB-δ precipitation can improve hot ductility but deteriorate strength for homogeneous grain configuration, adequate GB-δ particles can improve the deformation compatibility between GBs and γ-matrix to achieve good balance between the strength and ductility as well as smaller mechanical fluctuations. The heterogeneous duplexing grain configuration exhibited enhanced mechanical sensitivity to sluggish GB-δ precipitation since the hot ductility was rapidly reduced by tiny δ particles with fracture mode transition. In comparison, appropriate sub-solvus solution prior to aging cycles can introduce GB-δ particles pre-existed in homogeneous grain configuration to benefit in superior long-term static mechanical stability for Inconel 718 alloy.

Tobacco Mosaic Virus (TMV) and Potato Virus Y (PVY) pose significant threats to crop production. Non-destructive and accurate surveillance is crucial to effective disease control. In this study, we propose the adoption of hyperspectral and machine learning technologies to discern the type and severity of tobacco leaves affected by PVY and TMV infection. Initially, we applied three preprocessing methods – Multivariate Scattering Correction (MSC), Standard Normal Variate (SNV), and Savitzky-Golay smoothing filter (SavGol) – to corrected the leaf full-length spectral sheet data (350-2500nm). Subsequently, we employed two classifiers, support vector machine (SVM) and random forest (RF), to establish supervised classification models, including binary classification models (healthy/diseased leaves or PVY/TMV infected leaves) and six-class classification models (healthy and various severity levels of diseased leaves). Based on the core evaluation index, our models achieved accuracies in the range of 91–100% in the binary classification. In general, SVM demonstrated superior performance compared to RF in distinguishing leaves infected with PVY and TMV. Different combinations of preprocessing methods and classifiers have distinct capabilities in the six-class classification. Notably, SavGol united with SVM gave an excellent performance in the identification of different PVY severity levels with 98.1% average precision, and also achieved a high recognition rate (96.2%) in the different TMV severity level classifications. The results further highlighted that the effective wavelengths captured by SVM, 700nm and 1800nm, would be valuable for estimating disease severity levels. Our study underscores the efficacy of integrating hyperspectral technology and machine learning, showcasing their potential for accurate and non-destructive monitoring of plant viral diseases.

The lack of filler materials is the crucial issue that restricts the wide application of the advanced heat-resistance steel G115 in ultra-super critical (USC) power plants. In the present work, a new welding filler material with alloying system of 8.8Cr-2.7W-2.8Co was successfully developed to fabricate the G115 steel welded joint by the gas tungsten arc welding (GTAW), and post weld heat treatments (PWHT) involving different temperatures were proposed to tailor the mechanical properties. The filler material exhibited perfect compatibility with the base material (BM), and the manufactured welded joint displayed satisfactory appearance and defect-free weld section. After PWHT, full martensitic lath structure decorated with high density of dislocations and dispersed strengthening precipitates M23C6 and MX formed in the weld metal (WM), which was similar with that of the BM. Meanwhile, the welded joint was sensitive to the PWHT temperature, and an optimal combination of hardness (∼240 HV), tensile strength (∼679.9 MPa at 25 °C, and ∼344.6 MPa at 650 °C), elongation (∼13.1% at 25 °C, and ∼15.6% at 650 °C) and impact toughness (∼73.8 J/cm2) could be achieved after PWHT at 760 °C for 240 min. Comprehensively considering the obtained results, the designed filler material was feasible and reliable for matching the novel G115 steel, and satisfied the service demands of the G115 steel pipes in USC power plants.

Cotton is one of the most important natural fibers used in the textile industry worldwide. It is important to identify the key factors involved in cotton fiber development. In this study, zinc finger protein8 (GhZFP8) encoding a C2H2 transcription factor (TF) was cloned from cotton. qPCR showed that the transcripts of GhZFP8 in cotton were detected in the leaves and fibers at 3, 6, and 30 days post-anthesis (DPA), but not in the roots, stems, or flowers. The overexpression of GhZFP8 increased the trichome number on the siliques, leaves, and inflorescence, but inhibited the growth. The expression of trichome development and cell-elongation-related genes decreased obviously in GhZFP8 overexpressor Arabidopsis. Indole-3-acetic acid (IAA) and 1-Aminocyclopropanecarboxylic acid (ACC) contents were much higher in GhZFP8 overexpressors than that found in the wild type, but the gibberellin (GA) content was lower. The interference of GhZFP8 in cotton caused smaller bolls and shorter fibers than that of the control. The results of DNA affinity purification (DAP)-seq showed that GhZFP8 could bind to the promoter, exon, intron, and intergenic region of the target genes, which are involved in photosynthesis, signal transduction, synthesis of biomass, etc. Our findings implied that GhZFP8 processed multiple biological functions and regulated the development of cotton fiber.

In this paper, a Fe, Cr-rich multiphase Ni3Al-based alloy is joined through transient liquid phase bonding (TLP) technique. Different from typical γ+γ′ dual phase Ni3Al-based alloys, the joint can be divided into three distinct zones: isothermal solidification zone (ISZ), gamma prime zone (GPZ) and diffusion affected zone (DAZ). Interestingly, the massive fine grains with γ+γ′ dual phase are observed inside the ISZ, and the GPZ consists of blocky γ′ phase. The precipitation of Cr-rich borides in DAZ provides an advantageous compositional condition for the local coarsening of γ′ phase. In addition, hardness value of the bonded samples fluctuates from the centerline to the BM and reaches the peak at the DAZ. The bonded specimens share equivalent room-temperature tensile strength and elongation to failure with the parent metal after the weld thermal cycle. Moreover, the fracture path propagates along the base metal (BM), which indicates excellent tensile properties of the joint.

In the course of service, integral-forming aluminum foam sandwich (IFAFS) needed to bear three-point bending loads in different directions, however, its deformation mechanism and failure modes were still unclear. In this work, three-point bending performances of IFAFS under flatwise and edgewise bending conditions were investigated by experiment, in-situ micro X-ray tomography and digital volume correlation (DVC) calculation. The results showed that three-point bending performance was more stable under edgewise bending condition, and with the decrease of span length IFAFS presented three different failure modes of oblique core shear, asymmetric and symmetrical surface fracture. In addition, porosity mutation was a significant reason for crack initiation, and optimizing pore homogeneity was important to improve the performance and predictability of failure location. Different strengthening effect of sandwich structure anisotropy and different internal deformation evolutions caused by internal strain vortex were two main reasons which lead to performance difference of IFAFS with different solid panel directions. Connection of pre-existing micropores with dimple-like micropores generated during deformation process leads to the failure of IFAFS. The key factors to further optimize three-point bending performance and predictability of IFAFS was to homogenize the pore distribution of IFAFS.

Background: Previous studies have shown a potential beneficial effect of endovascular therapy (EVT) in patients with acute basilar artery occlusion (BAO). It was unclear that whether atrial fibrillation (AF) can affect the clinical outcomes for BAO patients treated with EVT. Objectives: To investigate the association between AF and clinical outcomes, and whether AF can modify the efficacy and safety of EVT in patients with BAO. Design: We conducted a multicenter, nationwide, retrospective analysis to investigate how the presence of AF affects treatment allocation for BAO patients. Methods: The endovascular treatment for acute basilar artery occlusion (ATTENTION) registry was a multicenter, prospective study in China that included acute BAO patients who underwent EVT or received best medical management (BMM) between 2017 and 2021. The outcomes include the distribution of 3-month modified Rankin scale (mRS) score, functional independence (defined as mRS 0–3), symptomatic intracerebral hemorrhage, and mortality. Results: 2134 patients were included in the study, of which 619 had AF and 1515 did not have AF. The median age was 65 (interquartile range [IQR]: 56–73) years, and 689 (32.3%) patients were female. Multivariate regression analysis indicated no significant association existed between AF and the distribution of mRS (adjusted common odds ratio, 1.05 [95% CI: 0.88, 1.25]; p = 0.564) at 90 days. Similarly, AF was not found to have a significant association with and other measured outcomes, or with the effects of EVT in AF subgroups for at 90 days as measured by ordinal mRS ( p for heterogeneity = 0.247). Finally, no significant differences were found for symptomatic intracerebral hemorrhage and mortality within 90 days between the EVT and BMM groups across AF subgroups. Conclusions: Our results illustrated that the effect of EVT did not differ statistically in acute ischemic stroke patients with and without AF. Moreover, no significant association between AF and functional or safety outcomes could be detected at 90 days.

The effect of solution temperature on the aging hardening behavior of Al-15%Mg2Si(-1%Cu) alloys was studied by characterizing the precipitation behaviors of nano-precipitates. After the solution temperature rises from 520 °C to 550 °C, more solute atoms are available for precipitation, and the formation activation energies of precipitates (β'' and S) decrease. So the formation of β''/β′ in Al-15%Mg2Si alloy and S in Al-15%Mg2Si-1%Cu alloy is accelerated at a solution temperature of 550 °C, which enhances the hardness and ultimate tensile strength (UTS) of the two alloys.

NASICON (Na superionic conductor)-type cathode materials for sodium-ion batteries (SIBs) have attracted extensive attention due to their mechanically robust three-dimensional (3D) framework, which has sufficient open channels for fast Na+ transportation. However, they usually suffer from inferior electronic conductivity and low capacity, which severely limit their practical applications. To solve these issues, we need to deeply understand the structural evolution, redox mechanisms, and electrode/electrolyte interface reactions during cycling. Recently, rapid developments in synchrotron X-ray techniques, neutron-based resources, magnetic resonance, as well as optical and electron microscopy have brought numerous opportunities to gain deep insights into the Na-storage behaviors of NASICON cathodes. In this review, we summarize the detection principles of advanced characterization techniques used with typical NASICON-structured cathode materials for SIBs. The special focus is on both operando and ex situ techniques, which help to investigate the relationships among phase, composition, and valence variations within electrochemical responses. Fresh electrochemical measurements and theoretical computations are also included to reveal the kinetics and energy-storage mechanisms of electrodes upon charge/discharge. Finally, we describe potential new developments in NASICON-cathodes with optimized SIB systems, foreseeing a bright future for them, achievable through the rational application of advanced diagnostic methods.

Metal borides/borates are promising candidates to become high-performance alkaline oxygen evolution reaction catalysts. This study reports an in-situ phase composition modulation approach to fabricate boride/borate-based catalysts.

Abstract Remote sensing and ground vegetation observation data show that climate warming promotes global vegetation greening, and the increase in air temperature in High Mountain Asia (HMA) is more than twice the global average. Under such a drastic warming in climate, how have the vegetation dynamics in HMA changed? In this study, we use the Normalized Difference Vegetation Index (NDVI) from 1982 to 2015 to evaluate the latest changes in vegetation dynamics in HMA and their climate-driving mechanisms. The results show that over the past 30 years, HMA has generally followed a “warm-wet” trend, with temperatures charting a continuous rise. During 1982–1998 precipitation increased (1.16 mm yr−1), but depicted to reverse since 1998 (− 2.73 mm yr−1). Meanwhile, the NDVI in HMA increased (0.012 per decade) prior to 1998, after which the trend reversed and declined (− 0.005 per decade). The main reason for the browning of HMA vegetation is the dual effects of warming and precipitation changes. As mentioned, the increase in air temperature in HMA exceeds the global average. The increase of water vapor pressure deficit caused by global warming accelerates the loss and consumption of surface water, and also aggravates the soil water deficit. That is to say, the abnormal increase of land evapotranspiration far exceeds the precipitation, and the regional water shortage increases. Climate change is the primary factor driving these vegetation and water dynamics, with the largest proportion reaching 41.9%.

Tungsten (W), as a promising plasma-facing material for fusion nuclear reactors, exhibits ductility reduction. Introducing high-density coherent nano-dispersoids into the W matrix is a highly efficient strategy to break the tradeoff of the strength–ductility performance. In this work, we performed helium (He) ion irradiation on coherent oxide-dispersoids strengthened (ODS) W to investigate the effect of coherent nanoparticle interfaces on the behavior of He bubbles. The results show that the diameter and density of He bubbles in ODS W are close to that in W at low dose of He ion irradiation. The radiation-induced hardening increment of ODS W, being 25% lower than that of pure W, suggests the involvement of the coherent interface in weakening He ion irradiation-induced hardening and emphasizes the potential of coherent nano-dispersoids in enhancing the radiation resistance of W-based materials.

Aggregation and coarsening of the second-phase oxide particles at grain boundaries have been a bottleneck for improving mechanical properties of oxide-dispersion-strengthened (ODS) alloys. Here the authors employ core-shell nanopowder precursors to achieve uniform dispersion of oxides in ODS alloys.

Two oxide dispersion strengthened (ODS) steels with compositions of 9Cr-ODS (9Cr-ODS) and 9Cr-3Al-ODS (9Cr-ODS-Al) were fabricated by hot isostatic pressing (HIP). The microstructures and precipitates of the ODS samples were characterized by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results showed that the addition of Al could reduce the precipitation of coarse M23C6 and optimized the size of carbides in ODS steels. Furthermore, it was found that the mean size of nanoparticles in 9Cr-ODS-Al is larger than that in 9Cr-ODS due to the formation of large-size Y–Al–O nanoparticles with Al addition. The tensile test results indicated that the addition of Al slightly decreased the strength of ODS steels, but substantially increased the ductility.

In this study, SiC particle (SICP)- and SiC whisker (SICW)-reinforced Cu composites were prepared by pulse intermittent deposition and subsequent spark plasma sintering (SPS). After electrodeposition, the formation of Cu-coated SICP and SICW core–shell structures solved the problem of agglomeration of the second phase during the subsequent sintering. In addition, the wetting layer of Cu increased the bonding strength of the interface between Cu and the second phase. The strength of SICP-reinforced Cu was higher than that of pure Cu at the expense of elongation and thermal conductivity. Compared to SICP-reinforced Cu, SICW-reinforced Cu exhibits significantly higher strength, plasticity and thermal conductivity. The externally applied load was transferred from a soft Cu matrix to stiff SICWs, thus increasing the yield strength of the composites. Furthermore, bridge cracks, crack deflection, and whisker pull-out mechanisms improved the elongation of the composite. This work reveals the relevance of the strengthening mechanism and the aspect ratio of the reinforced phase systematically and provides an advanced pathway to fabricate high-performance metal–matrix composites by designing discontinuous second phases with tailored aspect ratios.

ObjectiveThis study was conducted to determine the safety and efficacy of the Esperance® Distal Access Catheter (0.071”), a novel large bore aspiration catheter in treating acute ischemic stroke (AIS) with large vessel occlusion (LVO).MethodsA prospective multicenter clinical trial involving 15 stroke centers was performed. Baseline characteristics, procedural data, and angiographic and clinical outcomes of all acute stroke procedures (from May 2020 to March 2021) using the novel large bore aspiration catheter were analyzed.ResultsDuring the study period, 160 consecutive patients were recruited. The mean age and median baseline NIHSS were 65.4 years and 16, respectively. Successful reperfusion was achieved in 147 (91.9%) cases [at least modified Thrombolysis in Cerebral Infarction (mTICI) 2b] with aspiration alone, with complete reperfusion (mTICI 3) in 94 (58.8%) cases. Successful/complete first pass reperfusion was achieved in 104 (64.60%) cases, including mTICI 2b in 34 (21.1%) cases and mTICI 3 in 70 (43.5%) cases. The time from groin puncture to successful reperfusion was 44 (33, 62) min. There were 16 (9.9%) cases requiring rescue therapy using stent-retriever. Procedure-related complications included 2 (1.3%) cases of arterial perforation, 2 (1.3%) cases of arterial dissection, 12 (7.5%) cases of distal embolization, and 1(0.6%) case of puncture site infection. The rate of symptomatic intracranial hemorrhage (sICH) was 3.8% and mortality rate was 13.8%. A total of 99 (62.3%) cases had a favorable outcome (mRS 0–2) at 90 days.ConclusionsIn current practice, the first-line aspiration approach with the Esperance® Distal Access Catheter is safe and efficacious. This device may achieve high reperfusion rates with lower instances of rescue stent retriever therapy.

A counting problem on lattice points in n-dimensional space with rectangular coordinate system was considered. Lattice points are all the points having integer coordinates. The distances of these lattice points to the origin O are denoted from small to large as rn,0

Al-0.5Mg-0.4Si-0.1Cu alloy possessing weather resistance and oxidation resistance can obtain good surface quality (metallic luster) without chrome plating. Therefore, it is an important material to replace polluting chrome-plated aluminum profiles for automotive decorative parts. At present, studies about the extrusion process of Al-0.5Mg-0.4Si-0.1Cu alloy are very few, which affects its further application. In this work, the effect of extrusion ratios on microstructure and mechanical properties of Al-0.5Mg-0.4Si-0.1Cu alloy is investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. The results showed that the dynamic recrystallization degree of the alloy gradually increased with the extrusion ratio increasing, which is attributed to the driving force provided by the large extrusion ratio. Meanwhile, due to the occurrence of dynamic recrystallization, the texture changed from to orientation. In addition, grains were obviously refined and uniform with the extrusion ratio increasing. Due to the fine grain strengthening mechanism, the tensile strength and elongation of the alloy with an extrusion ratio of 30 reached 152 MPa and 32.4%.

In this work, twin wire arc additive manufacturing (T-WAAM) combined with in-situ alloying method was developed to fabricate multi-element alloys, and biomedical Ti-6Al-7Nb alloy with a good combination of strength and ductility was successfully fabricated for the first time. The modification of microstructure and the improvement of mechanical properties of the deposited Ti-6Al-7Nb alloy caused by Nb addition were investigated. Although demonstrated here for Ti-6Al-7Nb alloy, the combined method of T-WAAM and in-situ alloying is in principle applicable to fabricate other multi-element alloys by composition design, which is conductive to expanding the application fields of WAAM. IMPACT STATEMENT Twin wire arc additive manufacturing combined with in-situ alloying was developed to fabricate multi-element alloys, and biomedical Ti-6Al-7Nb alloy with a good combination of strength and ductility was first fabricated.

Effects of Y2W3O12 particle inclusions and content on damping capacity of Al–12Si composites have been investigated. The Y2W3O12, which is a kind of negative thermal expansion material, can generate high local strain in the composites. Thermal expansion testing shows that the coefficient of thermal expansion (CTE) of Y2W3O12 has obvious changes between 100 and 200 °C The Y2W3O12/Al–12Si composites show damping peaks and display higher damping capacities than the pure Al–12Si alloy. The damping capacities of composites strongly depends on the content of Y2W3O12 inclusions. A thermal strain damping model is also established. Based on the model analysis results, there is a significant contribution of thermal strain to the damping capacity in the composites; the change in CTE of Y2W3O12 could cause the generation of damping peaks. Moreover, dislocation damping and interfacial damping are also main damping mechanisms in the investigated composites.

Aqueous zinc (Zn) metal batteries are considered competitive candidates for next-generation energy storage, attributed to the abundance, low redox potential, and high theoretical capacity of Zn. However, conventional cathode materials are mainly based on ion-insertion electrochemistry, which can only deliver limited capacity. The conversion-type aqueous zinc–chalcogen batteries (AZCBs) have received widespread attention because they combine the advantages of chalcogen cathodes (S, Se, and Te) and Zn anodes to significantly enhance their capacity. Research on AZCBs has increased continuously; however, it is still in its infancy because the selection and regulation of cathode material systems are not comprehensive and systematic, and the investigation of the mechanisms is not thorough. Herein, we present a detailed overview explaining the recent progress of AZCBs, providing comprehensive guidelines for further research. First, research based on S cathodes, which is the most studied system among AZCBs, is summarized. Second, research based on Se and Te cathodes is described. Research on these different systems is mainly focused on electrolyte modification and cathode optimization. In each section, various strategies are introduced, and the working mechanisms are also discussed. Finally, the challenges and prospects for the development of AZCBs are presented.

Sediment discharge is widely regarded as a critical indicator of soil and water loss. The Mann–Kendall (M-K) test was applied to analyze the trends of temperature, precipitation, annual runoff, annual sediment discharge (ASD), and snow cover area proportion (SCAP). Sensitivity coefficient and contribution rate were adopted to assess the sensitivity of ASD to driving factors, and the contribution of driving factors to ASD. The results showed: (1) ASD of the Kaidu River and the Aksu River originating from Tien Shan decreased at rates of 3.8503 × 107 kg per year (p < 0.01) and 47.198 × 107 kg per year, respectively, from 2001 to 2019. The ASD there was also found to be more sensitive to SCAP changes in autumn and winter, respectively. (2) ASD of the Yarkand River and the Yulong Kashgar River originating from the Karakoram Mountains increased at rates of 21.807 × 107 kg per year and 27.774 × 107 kg per year, respectively, during 2001–2019. The ASD there was determined to be more sensitive to annual runoff. (3) In terms of contribution rate, except for the Kaidu River, annual runoff of the other three rivers made the largest contribution. (4) In addition, the proportion of glacial-melt water, slope, glacierization and human activities are also possible factors affecting sediment discharge.

Hydrological connectivity directly affects aquatic ecological processes, water environment and wetland ecological security, which is essential to the stability of arid ecosystems. However, the mechanism between hydrological connectivity and water-related environment has not been revealed completely. To address these issues, we use a landscape connectivity approach to assess the connectivity of water patches for analyzing the hydrological connectivity of the Bosten Lake Basin (BLB), as well as its response to human activities and climate change, based on the Joint Research Centre (JRC) global surface water dataset. It shows that the integral index of connectivity (IIC) of the BLB is low (ranging from 0 to 0.2) from 1990 to 2019, with an increasing interannual trend. The connectivity is higher in wet periods and in oases compared with dry periods and high-altitude mountain regions. Correlation and regression analyses indicate that hydrological connectivity has a strong correlation (r > 0.5, p ≤ 0.05) with water area and water level. The interannual and seasonal trends of eight hydrochemical indices in the Bosten Lake have been investigated to systematically elaborate the complex relationships between hydrological connectivity and water quality in the BLB. Results indicated that better hydrological connectivity can improve water quality, and the minimum of pollutants were observed in high hydrological connectivity period, covering approximately 75% of the high-water quality period. These findings could provide scientific support for the water management in the BLB.

Abstract Background Norcantharidin (NCTD), a demethylated derivative of cantharidin (defensive toxin of blister beetles), has been reported to exhibit insecticidal activity against various types of agricultural pests. However, NCTD applications are limited by its poor water solubility and high dosage requirement. Nanoemulsions have attracted much attentions due to the transparent or translucence appearance, physical stability, high bioavailability and non-irritant in nature. In general, nanoemulsions with small droplet size can enhance the bioavailability of drugs, whereas this phenomenon is likely system dependent. In present study, NCTD nanoemulsions were developed and optimized to evaluate and improve the insecticidal activity of NCTD against Plutella xylostella (Lepidotera: Plutellidae) by a spontaneous emulsification method. Results Triacetin, Cremophor EL and butanol were selected as the constituents of NCTD nanoemulsions via solubility determination, emulsification efficiency and ternary phase diagram construction. Insecticidal activity of NCTD nanoemulsion was associated with the content of surfactant and cosurfactant: (1) Higher effective toxicity exhibited at Smix (surfactant to cosurfactant mass ratio) = 3:1 that may be associated with the changes in interfacial tension; (2) NCTD nanoemulsion at 3:7

Lath martensite transformation in low carbon steel relates to the discontinuity of the transformation rate, which exhibits a series of martensite transformation rate maxima (peaks), especially in low cooling rates. In the present work, we put an emphasis on the influence of annealing twins in parent austenite grains (PAGs) and cooling rates on the discontinuity of lath martensite transformation rate in a low carbon reduced activation ferritic/martensitic (RAFM) steel. Lath martensite microstructure is hierarchical and the lath martensite transformation rate peaks are hierarchical during the cooling process. If the cooling rate was not high enough, the lath martensite transformation rate peaks will be divided into two groups by annealing twins in parent austenite. These transformation rate peaks in the first group were mainly caused by lath martensite transformation in the non–twin zones in the PAGs. Then, the second group mainly consisted of a single transformation rate peak, which was primarily caused by the martensite transformation in the twin zones in the PAGs. In the present work, a new “localized stress field” theory is proposed and successfully used for interpreting the classification mechanism of lath martensite transformation rate peaks and the evolution of these peaks with changing cooling rate.

Abstract Iron/manganese‐based layered transition metal oxides have risen to prominence as prospective cathodes for sodium‐ion batteries (SIBs) owing to their abundant resources and high theoretical specific capacities, yet they still suffer from rapid capacity fading. Herein, a dual‐strategy is developed to boost the Na‐storage performance of the Fe/Mn‐based layered oxide cathode by copper (Cu) doping and nanoengineering. The P2‐Na0.76Cu0.22Fe0.30Mn0.48O2 cathode material synthesized by electrospinning exhibits the pearl necklace‐like hierarchical nanostructures assembled by nanograins with sizes of 50–150 nm. The synergistic effects of Cu doping and nanotechnology enable high Na+ coefficients and low ionic migration energy barrier, as well as highly reversible structure evolution and Cu/Fe/Mn valence variation upon repeated sodium insertion/extraction; thus, the P2‐Na0.76Cu0.22Fe0.30Mn0.48O2 nano‐necklaces yield fabulous rate capability (125.4 mA h g−1 at 0.1 C with 56.5 mA h g−1 at 20 C) and excellent cyclic stability (≈79% capacity retention after 300 cycles). Additionally, a promising energy density of 177.4 Wh kg−1 is demonstrated in a prototype soft‐package Na‐ion full battery constructed by the tailored nano‐necklaces cathode and hard carbon anode. This work symbolizes a step forward in the development of Fe/Mn‐based layered oxides as high‐performance cathodes for SIBs.

Corrosion behaviors of Al-15%Mg2Si-1%Ni alloy in 3.5% NaCl solution were studied by characterizing the corrosion morphologies of Al3Ni, Mg2Si, and Al phases. The results show that there are two galvanic coupling systems (Al/Al3Ni and Al/Mg2Si) in Al-15%Mg2Si-1%Ni alloy. In the Al/Al3Ni coupling system, the intermetallic Al3Ni phase (nobler than the Al matrix) acts as the cathode throughout the corrosion process. For the Al/Mg2Si coupling system, electrochemical polarity conversion occurs between the Al matrix and the Mg2Si phase. The corrosion pits around the Al3Ni and Mg2Si are connected to form long corrosion channels, which accelerate corrosion of the Al-Mg2Si-Ni alloys.

Abstract Perovskite‐based light‐emitting diodes (PeLEDs) are now approaching the upper limits of external quantum efficiency (EQE); however, their application is currently limited by reliance on lead and by inadequate color purity. The Rec. 2020 requires Commission Internationale de l'Eclairage coordinates of (0.708, 0.292) for red emitters, but present‐day perovskite devices only achieve (0.71, 0.28). Here, lead‐free PeLEDs are reported with color coordinates of (0.706, 0.294)—the highest purity reported among red PeLEDs. The variation of the emission spectrum is also evaluated as a function of temperature and applied potential, finding that emission redshifts by

In this paper, the interactions between interstitial oxygen atoms and substitutional atoms in Ti–Nb–O alloys were investigated by first-principles calculations based on the density functional theory. The binding energies and formation energies of oxygen atoms sited were calculated in various interstices with different geometries, element species, and atomic arrangements. The calculation results showed that there was a strong repulsive binding energy between the interstitial oxygen and the substitutional niobium atoms. On this basis, the energetically favored sites and the distribution of interstitial oxygen atoms in Ti–Nb–O alloys were discussed and demonstrated by an electron energy loss spectroscopy method. Furthermore, the diffusion activation energies of interstitial oxygen atoms based on the formation energy results were presented, and the diffusion behaviors of interstitial oxygen atoms in Ti–Nb–O alloys were also discussed.

Taitema Lake, located in the lower reaches of the Tarim River and the Cherchen River, is one of the most important ecological barriers in Ruoqiang County. The amount of water in Taitema Lake plays an important role in maintaining a healthy cycle within the ecosystem, curbing sandstorms, and improving salinization and desertification. The aim of this study was to reasonably determine the volume of ecological water conveyance by calculating the ecological water demand. We systematically analyzed the spatial and temporal variation characteristics of Taitema Lake during 21 ecological water conveyance processes from 2000 to 2020. The results showed that the area of Taitema Lake increased at a rate of 144% per year because of the Ecological Water Conveyance Project (EWCP). The areas of water in dry, normal, and high flow years were 30.35, 57.76, and 103.5 km2, respectively. The corresponding ecological water demand was 1.58 × 108, 3.09 × 108, and 5.66 × 108 m3, respectively. We calculated that the Cherchen River and the Tarim River carried 0.87 × 108–3.11 × 108 m3 and 0.71 × 108–2.55 × 108 m3 of water, respectively, under different inflow frequencies. This study has significance as a reference for estimates of the ecological water demand of terminal lakes under the condition of artificial water transport in arid inland river basins, and provides the basis for the rational allocation of water resources in the Tarim River Basin.

The microstructural evolution of primary Mg2Si in Al–20%Mg2Si with Al–3%P master alloy was observed by scanning electron microscope. And the interfacial properties of AlP/Mg2Si interface were investigated using first-principles calculations. The calculation results show that AlP(1 0 0)/Mg2Si(2 1 1) and AlP(3 3 1)/Mg2Si(1 1 0) interfaces can form steadily. P-terminated AlP(1 0 0)/Mg2Si(2 1 1) interface with the largest work of adhesion (4.13 J/m2) is theoretically the most stable. The interfacial electronic structure reveals that there are covalent Si–Al, Si–P and Mg–P bonds existing between AlP and Mg2Si slabs. Due to the AlP particles as effective heterogeneous nucleus of Mg2Si, primary Mg2Si particles change from dendrite to octahedron/truncated octahedron, and their sizes decrease to ∼20 μm. Keywords: AlP, Al–Mg2Si alloys, First-principles calculation, Heterogeneous nucleus

The purpose of this work was to evaluate the possibility of adding tea saponin (TS) to reduce the synthetic surfactant concentration, and maintain or improve the shelf stability of nanoemulsions. The Zanthoxylum bungeanum essential oil (2.5 wt%) loaded oil-in-water nanoemulsions were co-stabilized by Tween 40 (0.5–2.5 wt%) and TS (0.1–5 wt%). A combination of several analytical techniques, such as dynamic laser scattering, interfacial tension, zeta potential, and transmission electron microscope, were used for the characterization of nanoemulsions. Low levels of TS (0.1–0.5 wt%) with Tween 40 had significant effects on the emulsification, and a nanoemulsion with the smallest droplet diameter of 89.63 ± 0.67 nm was obtained. However, in the presence of high TS concentration (0.5–5 wt%), micelles generated by the non-adsorbed surfactants in the aqueous lead to droplets growth. In addition, the combinations of Tween 40 and TS at the high level (>3.5 wt%) exerted a synergistic effect on stabilizing the nanoemulsions and preventing both Ostwald ripening and coalescence. The negative charged TS endowed the droplets with electrostatic repulsion and steric hinderance appeared to prevent flocculation and coalescence. These results would provide a potential application of natural TS in the preparation and stabilization of nanoemulsions containing essential oil.

Asia currently has the world’s largest arid and semi-arid zones, so a timely assessment of future droughts in the Asian drylands is prudent, particularly in the context of recent frequent sandstorms. This paper assesses the duration, frequency, and intensity of drought events in the Asian drylands based on nine climate models of the Coupled Model Intercomparison Project Phase 6 (CMIP6). The results show that a high percentage of land area is experiencing significant drought intensification of 65.1%, 89.9%, and 99.8% under Shared Socioeconomic Pathways (SSP)126, SSP245, and SSP585 scenarios, respectively. Furthermore, the data indicate that future droughts will become less frequent but longer in duration and more intense, with even more severe future droughts predicted for northwest China and western parts of Uzbekistan and Kazakhstan. Drought durations of 10.8 months and 13.4 months are anticipated for the future periods of 2021–2060 and 2061–2100, respectively, compared to the duration of 6.6 months for the historical period (1960–2000). Meanwhile, drought intensity is expected to reach 1.37 and 1.66, respectively, for future events compared to 0.97 for the historical period. However, drought severity under SSP245 will be weaker than that under SSP126 due to the mitigating effect of precipitation. The results of this study can provide a basis for the development of adaptation measures in Asian dryland nations.

Near surface wind speed has significant impacts on ecological environment change and climate change. Based on the CN05.1 observation data (a gridded monthly dataset with the resolution of 0.25 latitude by 0.25 longitude over China), this study evaluated the ability of 25 Global Climate Models (GCMs) from Coupled Model Intercomparison Project phase 6 (CMIP6) in simulating the wind speed in the Arid Region of Northwest China (ARNC) during 1971–2014. Then, the temporal and spatial variations in the surface wind speed of ARNC in the 21st century were projected under four Shared Socioeconomic Pathways (SSPs), SSP1-2.6, SSP2-4.5, SSP3-7.0, and SP5-8.5. The results reveal that the preferred-model ensemble (PME) can fairly evaluate the temporal and spatial distribution of surface wind speed with the temporal and spatial correlation coefficients exceeding 0.5 at the significance level of p = 0.05 when compared to the 25 single models and their ensemble mean. After deviation correction, the PME can reproduce the distribution characteristics of high wind speed in the east and low in the west, high in mountainous areas, and low in basins. Unfortunately, no models or model ensemble can accurately reproduce the decreasing magnitude of observed wind speed. In the 21st century, the surface wind speed in the ARNC is projected to increase under SSP1-2.6 scenario but will decrease remarkably under the other three scenarios. Moreover, the higher the emission scenarios, the more significant the surface wind speed decreases. Spatially, the wind speed will increase significantly in the west and southeast of Xinjiang, decrease in the north of Xinjiang and the south of Tarim Basin. What’s more, under the four scenarios, the surface wind speed will decrease in spring, summer and autumn, especially in summer, and increase in winter. The wind speed will decrease significantly in the north of Tianshan Mountains in summer, decrease significantly in the north of Xinjiang and the southern edge of Tarim Basin in spring and autumn, and increase in fluctuation with high values in Tianshan Mountains in winter.

Abstract With the aim of preparing high performance oxide-dispersion-strengthened tungsten based alloys by powder metallurgy, the W-Y2O3 composite nanopowder precursor was fabricated by an improved wet chemical method with anion surfactant sodium dodecyl sulfate (SDS) addition. It is found that the employment of SDS can dramatically decrease W grain size (about 40 nm) and improve the size uniformity. What’s more, SDS addition can also remarkably improve the uniform dispersion of Y2O3 particles during the synthesis process. For the alloy whose powder precursor was fabricated by traditional wet chemical method without SDS addition, only a few Y2O3 dispersoids with size of approximate 10–50 nm distribute unevenly within tungsten grains. Nevertheless, for the sintered alloy whose powder precursor was produced by improved wet chemical method, the Y2O3 dispersoids (about 2–10 nm in size) with near spherical shape are dispersed well within tungsten grains. Additionally, compared with the former, the alloy possesses smaller grain size (approximate 700 nm) and higher relative density (99.00%). And a Vickers microhardness value up to 600 Hv was also obtained for this alloy. Based on these results, the employment of SDS in traditional wet chemical method is a feasible way to fabricate high performance yttria-dispersion-strengthened tungsten based alloys.

In this work, the effect of Y2O3 addition on the grain growth and densification of W matrix was explored from a kinetic perspective by comparing the low temperature sintering behavior of W-Y2O3 composite nanopowder system with that of pure W nanopowder system. By combining nonisothermal sintering experiment with the power law of grain growth, it was found that grain boundary diffusion is responsible for the mass transport mechanism in both systems. The inhibition of W grain growth after Y2O3 addition is closely related to the lower surface diffusivity of W skeleton. The densification rate of W skeleton in these two systems were modelled using a periodic 3D arrangement of identical particles and a much smaller grain boundary diffusivity of W skeleton was obtained for W-Y2O3 sample. Firstly, it is the decrease in dihedral angle of W matrix after Y2O3 addition that causes a decrease in thermodynamic driving force for densification. Secondly, from the view of atomic mobility, the inhibited W grain growth caused by limited surface diffusivity is one of the reasons impeding densification. Besides, Y2O3 grains distributed at W grain boundary coarsen through wetting W grain boundary, which also has an inhibition effect on the W skeleton densification. Keywords: W-Y2O3, Grain growth, Densification, Kinetics, Interfacial energy