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In the continuous cooling process, the growth of the equiaxed α-phase grains in near-α high-temperature titanium alloys is controlled by the diffusion of alloying elements. Establishing a specific connection between the cooling rate and the diffusion behaviour of alloying elements aids in the precise prediction of the evolution of equiaxed α-phase grain size. This study meticulously controlled the cooling rate during the two-phase region annealing treatment of the Ti65 alloy. Using EPMA technology, the diffusion behaviour of solute elements during cooling was accurately characterized. The study found that slowing the cooling rate promotes the coarsening of the lamellar secondary α-phase grains and the growth of the primary equiaxed α-phase grains. At higher annealing temperatures, the growth of equiaxed α-phase grains can occur at faster cooling rates, while coarse lamellar secondary α-phase grains can be retained at slower cooling rates. The diffusion behaviour of solute elements Al, Ta, Mo, and W between the α-phase and transformed β-phase matrix is significantly influenced by the cooling rate, thus they are considered as the controlling elements for the growth of the equiaxed α-phase grains. Based on the diffusion behaviours of these controlling elements, their single-element diffusion models were categorized and integrated for predicting the grain size of the equiaxed α-phase. The predictions from the revised diffusion model show an excellent agreement with the actual results, with an error margin of about 5%.

Abstract Machine learning has been widely used to guide the search for new materials by learning the patterns underlying available data. However, the pure prediction-oriented search is often biased to interpolation due to the limited data in a large unexplored space. Here we present a sampling framework towards extrapolation, that integrates unsupervised clustering, interpretable analysis, and similarity evaluation to sample target candidates with improved properties from a vast search space. Using the design of superalloys with improved $${\gamma }^{{\prime} }$$ γ ′ -phase solvus temperature ( $${T}_{{\gamma }^{{\prime} }}$$ T γ ′ ) as a model case, we start with sparse data, and by a few experiments, we find nine new superalloys with chemistries distinct to those in the training data. Three of them show improved $${T}_{{\gamma }^{{\prime} }}$$ T γ ′ by about 50 °C, a large enhancement for superalloys. Moreover, we find two features characterizing mismatch in atomic size and mixing enthalpy linearly effect. This work demonstrates the capability of unsupervised learning to search for new materials when limited data is available.

This work elucidates the interactions between Re and hydrogen at γ/γ′ interfaces, enhancing the hydrogen-embrittlement resistance of nickel-based single-crystal superalloy (Ni-SX). The H-charged Ni-SX exhibits severe embrittlement characterized by the appearance of parallel dislocation slip bands and micro-cracks, which could be effectively mitigated through improving the Re content. The segregation behaviors of hydrogen at γ/γ′ interfaces, as captured by hydrogen microprint technique, significantly diminish interfacial cohesion strength by reducing the local atomic bonding strength. Detailed characterizations of bonding charge density highlight that Re plays a crucial role in reducing hydrogen embrittlement susceptibility by suppressing the hydrogen-induced degradation of bonding strength.

In this study, we report a novel high-Mn Fe–21Mn–6Al–4Si–1C (wt.%) duplex lightweight steel with concurrent chemical ordering and twinning-induced plasticity effects. This steel is capable of achieving an exceptional combination of strength and ductility following either cold-rolling and annealing at 1000 °C or subsequent short-term aging at 550 °C. In its as-annealed state, this steel primarily consists of γ-austenite and α-ferrite, with α-ferrite appearing as dispersed particles within fully recrystallized γ grains. Furthermore, L′12- and D03-type ordered nanodomains exist within these two phases, respectively. The aging treatment negligibly affects the size and volume fraction of both the γ-austenite and α-ferrite, yet it enhances the degree of ordering as well as the size and volume fraction of their ordered nanodomains, leading to a rise in yield strength from ∼800 to ∼1062 MPa and a decline in total elongation from ∼60.4% to ∼44.4%. The high yield strength of this steel originates from multiple strengthening mechanisms involving dislocation interactions with solute atoms, ordered nanodomains, γ grain boundaries and γ/α phase boundaries. This steel plastically deforms via planar slip during the initial stages. The rather small γ grain size, coupled with the presence of hard α-ferrite particles, fosters the dynamic slip band refinement (DSBR) effect, thereby enhancing the flow stress sufficiently to trigger deformation twinning in the steel during the later stages. The DSBR effect, combined with the progressive formation of deformation twins, stacking faults and Lomer-Cottrell locks, imparts pronounced strain hardenability to this steel, leading to its outstanding ductility.

The evolution of martensite and the tensile deformation behavior of Ti-7333 alloy with different β grain size was studied. It is found that the β grain size (45–260 μm) significantly affects the triggering stress of stress-induced α″ martensite (SIMα″), and then affects the distribution and morphology of α″ martensite. At the initial stage of deformation, the larger β grain can inhibit the stress-induced secondary α″ martensitic transformation and the formation of α″ twinning. While under the same strain, the stress-induced martensite and martensite twinning can be activated simultaneously in the alloy with the smaller β grain, including {111}α″ type Ⅰ twinning, {130}α″ compound twinning, α″ type Ⅱ twinning, {021}α″ type Ⅱ twinning, which can effectively accommodate localized strains and improve the work hardening rate of Ti-7333 alloy. When the β grain size varies in the range of 45–84 μm, there is a higher work hardening plateau in the deformation stage II of Ti-7333 alloy. The yield strength and β grain size are in accordance with the Hall-Petch relation. As the grain size increases to 128 even to 260 μm, the work hardening rate continues to decrease and the yield strength inversely increases. It is demonstrated that the triggering stress for SIMα″ exhibits U-shaped fluctuations as β grain size increases, and the inflection point of Ti-7333 alloy is between 84 μm and 260 μm.

By elucidating the progressive relationship from the rolling stress state to the activation of slip systems and then to lattice rotation, this paper clarifies the influence mechanism of strain paths on the evolution of α-phase texture in near-α titanium alloys. The distinct rolling textures obtained further provide a robust foundation for investigating whether the competition between different α-phase textures changes with varying cooling rates during β→α phase transformation. In this study, initial Ti65 alloy sheets underwent rolling using three different strain paths (UDR/CDR/MSCR), resulting in the production of three foils characterized by distinct textures. Compressive stress during rolling promotes the activation of basal and pyramidal-II slipping, leading to the formation of a TD-split basal texture in α-phase. Tensile stress during rolling promotes the activation of prismatic slipping, ultimately resulting in a [10 1‾ 0]//RD (in the case of UDR) or [21‾1‾ 0]//RD (in the case of CDR) texture. Variations in stress states along different strain paths led to differences in the global Schmid factor distribution of α-phase for slip systems, ultimately resulting in diverse texture evolution. Subsequently, foil samples underwent two-phase region heat treatments, followed by furnace cooling and air cooling. After furnace cooling, the strength of the transverse texture increased in each type of foils. Conversely, after air cooling, no specific α-phase texture consistently exhibited an increasing trend in the three foils.

The issue of whether CoCrFeNi is a single-phase or dual-phase high-entropy alloy (HEA) has long been in dispute. In this study, CoCrFeNi has been verified to be a dual-phase HEA composed of dendritic phases with an FCC structure and inter-dendritic phases with a BCC structure. The BCC phases within inter-dendritic regions are identified as Cr3O oxides which form inevitably under the arc-melting process. Undercooling treatment under a strong magnetic field can regulate the composition and precipitation of the BCC phase, refine the grain size, and enhance the solid solubility, consequently, the mechanical performances of CoCrFeNi HEA are effectively enhanced.

In this work, different transformed β matrix was obtained in Ti–5Al–7.5 V alloy. The alloy with equiaxed αp phase and transformed β matrix containing α′ martensite and β phase exhibits good combination of strength and plasticity, as well as a high work hardening rate. A concurrent operation of stress-induced α″ martensitic transformation, deformation twinning and dislocation slips was observed governing the deformation process of this alloy. The alloy with equiaxed αp phase and transformed β matrix containing secondary αs plates and retained β phase shows a high strength and plasticity but low work hardening rate, which is caused by dislocation slips.HighlightsThe quenched Ti–5Al–7.5 V alloy exhibits a high work hardening rate, approximately 5500 MPa.The dependence of work hardening rate of Ti–5Al–7.5 V alloy on transformed β matrix is revealed.Concurrent operations of stress-induced α″ martensitic transformation, deformation twinning and dislocation slips govern deformation of the studied alloy.

Dissimilar TiAl-based alloys weld by solid-state bonding, also known as diffusion bonding (DB), usually show brittle intermetallic compounds, high interfacial stress, and poor properties. A novel post-bonded process strategy, slight deformation in the direction of stress parallel to the bonding interface, was developed in the post-bonded treatment of the TiAl/Ti2AlNb joint. The effect of post-bonded processes on the interfacial microstructure, element diffusion, fracture characteristics and mechanical properties were systematically investigated. The results showed that the post-bonded hot deformation (PBHD), compared to the traditional post-bonded heat treatment (PBHT), can effectively increase the major elements diffuse and the growth of the reaction layer, as well as promote the precipitates which distribute uniformly in the reaction layer, finally resulting in superior tensile strength. Compared with the DB samples, the ultimate tensile strength of the PBHD joint increased by 45.58%. In addition, the fracture behavior was further analyzed based on the microfracture morphology and crack propagation path. These findings will facilitate the development of advanced manufacturing processes of blisk for high-temperature light alloys.

The rectangular billet of TNM alloy with oriented lamellar microstructure was obtained by extrusion above its α transus temperature. The as-extruded TNM alloy exhibits a nearly lamellar microstructure with an average colony size of approximately 60 μm, and the proportion of lamellar colonies with an angle between the interface and the extrusion direction less than 30° exceeds 70 %. EBSD results show that strong basal texture of α phase with basal planes parallel to the extrusion direction was formed during the extrusion process in the (α+β) two-phase field. During the subsequent cooling process, the γ lamellae precipitates along the (0001) plane of α phase according to the Blackburn orientation relationship, allowing the lamellar structure to inherit the orientation of the parent phase. Tensile test results indicate that the strength and fracture elongation of the as-extruded TNM alloy along the extrusion direction (ED) increased simultaneously, which were 1100 MPa and 1.26 %, respectively. The hindrance effect of interfaces on dislocations and stacking faults in lamellar colonies parallel to the extrusion direction helps to improve strength, while the activation of the prismatic slip and pyramidal slip systems in the α2 lamellae is beneficial to the plasticity. This study shows that it is feasible to control the lamellar orientation and improve the mechanical properties of TNM alloy by extrusion above its α transus temperature.

The real-time, full-field simulation of the tube hydroforming process is crucial for deformation monitoring and the timely prediction of defects. However, this is rather difficult for finite-element simulation due to its time-consuming nature. To overcome this drawback, in this paper, a surrogate model framework was proposed by integrating the finite-element method (FEM) and machine learning (ML), in which the basic methodology involved interrupting the computational workflow of the FEM and reassembling it with ML. Specifically, the displacement field, as the primary unknown quantity to be solved using the FEM, was mapped onto the displacement boundary conditions of the tube component with ML. To this end, the titanium tube material as well as the hydroforming process was investigated, and a fairly accurate FEM model was developed based on the CPB06 yield criterion coupled with a simplified Kim–Tuan hardening model. Numerous FEM simulations were performed by varying the loading conditions to generate the training database for ML. Then, a random forest algorithm was applied and trained to develop the surrogate model, in which the grid search method was employed to obtain the optimal combination of the hyperparameters. Sequentially, the principal strain, the effective strain/stress, as well as the wall thickness was derived according to continuum mechanics theories. Although further improvements were required in certain aspects, the developed FEM-ML surrogate model delivered extraordinary accuracy and instantaneity in reproducing multi-physical fields, especially the displacement field and wall-thickness distribution, manifesting its feasibility in the real-time, full-field simulation and monitoring of deformation states.

Accurate and timely information on farmland size is crucial for agricultural development, resource management, and other related fields. However, there is currently no mature method for estimating farmland size in smallholder farming areas. This is due to the small size of farmland plots in these areas, which have unclear boundaries in medium and high-resolution satellite imagery, and irregular shapes that make it difficult to extract complete boundaries using morphological rules. Automatic farmland mapping algorithms using remote sensing data also perform poorly in small-scale farming areas. To address this issue, this study proposes a farmland size evaluation index based on edge frequency (ECR). The algorithm utilizes the high temporal resolution of Sentinel-2 satellite imagery to compensate for its spatial resolution limitations. First, all Sentinel-2 images from one year are used to calculate edge frequencies, which can divide farmland areas into low-value farmland interior regions, medium-value non-permanent edges, and high-value permanent edges (PE). Next, the Otsu’s thresholding algorithm is iteratively applied twice to the edge frequencies to first extract edges and then permanent edges. The ratio of PE to cropland (ECR) is then calculated. Using the North China Plain and Northeast China Plain as study areas, and comparing with existing farmland size datasets, the appropriate estimation radius for ECR was determined to be 1600 m. The study found that the peak ECR value for the Northeast China Plain was 0.085, and the peak value for the North China Plain was 0.105. The overall distribution was consistent with the reference dataset.

This paper has investigated the growth of α grain during lamellar decomposition of Ti‐48Al‐7Nb‐2.5V‐1Cr alloy. In the (α + γ) phase region, the α grains have started to grow by consuming the adjacent α grains, accompanied by decomposition of γ lamellae (γL). Since the growth rate of α grains is faster than the decomposition of γL, the growth of the α grains is hindered by the γL, while the hindering effect decreases with the γL decomposition. Once the hindrance of the γL is gone, the α grains will continue to grow and the grain size can even reach the millimetre level. The α grain growth does not show a specific pattern. The growing α grain may also be consumed by the adjacent α grains, resulting in irregular grain morphology.

The traditional volume-derived biomass method is limited because it does not fully consider the carbon sink of young trees, which leads to the underestimation of the carbon sink capacity of a forest ecosystem. Therefore, there is an urgent need to establish an allometric biomass model of young trees to provide a quantitative basis for accurately estimating the carbon storage and carbon sink of young trees. The destructive data that were used in this study included the biomass of the young trees of the two dominant species (Betula pendula subsp. mandshurica (Regel) Ashburner & McAll and Populus × tomentosa Carrière) in China, which was composed of the aboveground biomass (Ba), belowground biomass (Bb), and total biomass (Bt). Univariate and bivariate dimensions were selected and five candidate biomass models were independently tested. Two additive allometric biomass model systems of young trees were established using the proportional function control method and algebraic sum control method, respectively. We found that the logistic function was the most suitable for explaining the allometric growth relationship between the Ba, Bt, and diameter at breast height (D) of young trees; the power function was the most suitable for explaining the allometric growth relationship between the Bb and D of young trees. When compared with the independent fitting model, the two additive allometric biomass model systems provide additive biomass prediction which reflects the conditions in reality. The accuracy of the Bt models and Ba models was higher, while the accuracy of the Bb models was lower. In terms of the two dimensions—univariate and bivariate, we found that the bivariate additive allometric biomass model system was more accurate. In the univariate dimension, the proportional function control method was superior to the algebraic sum control method. In the bivariate dimension, the algebraic sum control method was superior to the proportional function control method. The additive allometric biomass models provide a reliable basis for estimating the biomass of young trees and realizing the additivity of the biomass components, which has broad application prospects, such as the monitoring of carbon stocks and carbon sink evaluation.

The accurate assessment of tree volume is crucial for developing forest management plans, and this can be achieved using tree volume models. In this study, data on individual trees were collected and calculated, including the diameter at breast height (D), ground diameter (DG), tree height (H), and tree volume (V). A total of 400 Populus × tomentosa Carrière, 400 Populus tomentosa Carr, and 400 Populus × canadensis Moench trees were sampled. Two compatible volume model systems were established using corresponding methods. The models consisted of the following five types: V-DH, V-D, V-DG, H-D, and DG-D. In our calculations, before the horizontal line was the dependent variable, and behind the horizontal line was the independent variable. Variations in preferences for the H-D models were observed among the tree species, with the logistic function proving the most suitable for Populus × tomentosa Carrière, Chapman–Richard function for Populus tomentosa Carr, and power function for Populus × canadensis Moench. Among the three volume models, the V-DH model exhibited a superior performance, with its R2 values ranging from 0.965 to 0.984 and mean estimated error (MPE) values ranging from 1.26% to 1.78%. Following this was the V-D model, with R2 values between 0.9359 and 0.9704 and MPE values between 1.71% and 2.46%. The V-DG model ranked third, with R2 values ranging from 0.8746 to 0.9501 and MPE values ranging from 2.33% to 3.16%. In the H-D model, the R2 and MPE values ranged from 0.4998 to 0.7851 and from 1.31% to 1.45%, respectively. For the DG-D model, the R2 values ranged from 0.9563 to 0.9868 and the MPE values ranged from 0.47% to 0.68%. Comparing both compatible methods, the nonlinear seemingly uncorrelated regression (NSUR) was more effective. The three volume models demonstrated high levels of accuracy and compatibility, providing a reliable scientific foundation for forest management and the formulation of harvesting plans in Beijing, with significant practical implications.

ABSTRACTSelective laser melted (SLMed) AlSi10Mg alloys usually fail before necking during tensile tests, which results in inadequate ductility. To overcome this problem, here we introduced Al4C3 nanorods into the primary Al cells of SLMed AlSi10Mg via in-situ chemical reaction. Tensile tests revealed that those in-cell Al4C3 nanorods not only increased the strain-hardening ability of SLMed AlSi10Mg but also delayed the fracture beyond necking. Consequently, 15% of tensile strength increase and 78% of ductility increase were achieved simultaneously. Post-tensile TEM analysis revealed that those in-cell Al4C3 nanorods pinned and accumulated dislocations within cells and thus alleviated stress concentration along cell boundaries.

This work reports that the plastic deformation mechanism of lamellar microstructure (LM) in Ti-43.5Al-4Nb-1Mo-0.1B (TNM) alloy transforms from stacking faults (SFs)-dominated process to long-period stacking ordering (LPSO) structures-mediated process with a slight increase in lamellar spacing (LS) (20–36 nm). Multiple LPSO bands significantly enhance the work hardening response and trigger the transformation-induced plasticity (TRIP) effect, causing a four-fold higher ductility than SF-deformed LM at 750°C without compromising yield strength (YS). This phenomenon provides novel insights into the development of high-performance TiAl alloys with extremely nano-LM (LS

Abstract Supercapacitors have been used in a broad range of fields including electronics, transportation, and energies. Electrode materials with high capacitance and good rate performance are crucial for the future development and application of supercapacitors. Herein, we prepared N, O co‐doped defective carbon blocks (NO‐DCBs) with abundant active sites through carbonization and ball‐milling of polyimide. The as‐obtained NO‐DCBs exhibit high atomic content of N and O inherited from polyamic acid (PAA) precursor, as well as large amounts of intrinsic defects introduced by ball‐milling. Benefiting from the synergy of pseudocapacitance and electrical double‐layer capacitance provided by heteroatoms and intrinsic defects respectively, the NO‐DCBs assembled symmetric aqueous capacitor shows high capacitance of 329 F g−1 at 0.1 A g−1, good rate performance of 48% capacitance retention at 50 A g−1, and superb cycling stability. This work promotes the deep understanding of the synergy effect of functional groups and intrinsic defects for capacitive energy storage, and broadens the avenue for structural design of active sites in carbon materials.

In this study, ternary Cu52Co24Fe24 immiscible alloys are prepared with varying undercoolings and under a high magnetic field. The microstructure evolution and properties of the alloys are investigated. The temperature range of the immiscible gap is determined using CALPHAD. According to the excess Gibbs free energy of liquid, the addition of Fe promotes the demixing tendency of the Cu–Co–Fe ternary system during solidification. With the application of a magnetic field, the (Fe, Co)-rich phases transform from a globular shape to an elongated form along the direction of the magnetic field during solidification, which is due to the existence of the counteracting behavior of the interparticle magnetic dipole-dipole force at the critical droplet size. Under a high magnetic field, the obtained samples had a more dispersed minority phase, higher microhardness and better conductivity. However, the saturation magnetization of the samples with large undercooling decreases with increasing magnetic field due to the suppression of the phase separation behavior under a high magnetic field. This study proposes a novel technology for preparing immiscible alloys with excellent properties by applying a superimposed magnetic field during solidification.

Laser powder bed fused (LPBFed) AlSi10Mg is recognised for its superior mechanical properties. However, its thermal stability has never been justified. Herein, we exposed as-built AlSi10Mg to different temperatures (200–500°C) for only 3 min to evaluate its thermal stability. Results showed that LPBFed AlSi10Mg had relatively low thermal stability. Only 3 min of thermal exposure at 200°C would deteriorate its tensile strength dramatically. Microstructural analysis revealed that with increasing thermal input, as-built AlSi10Mg exhibited a microstructural evolution similar to annealing of cold-worked metals, namely recovery, recrystallisation followed by grain-growth. The excessive energy stored in as-built microstructure due to fast cooling during LPBF was deduced as the driving force for this phenomenon. Therefore, such microstructural change was at the expense of dislocations stored in the as-built material, which in turn caused deterioration in tensile strength. The present findings may provide guidance for the application of LPBFed AlSi10Mg.

A novel, efficient and environmentally friendly solvent-free and catalyst-free approach for the synthesis of structurally diverse gem-difluorinated and polyfluoroarylated derivatives with readily available nucleophilic and electrophilic fluorine-containing reaction partners, difluoroenoxysilane and pentafluorobenzaldehyde, is described. This neat protocol is induced by the direct hydrogen-bond interactions between fluorinated and non-fluorinated reactants without the use of heavy metal catalysts or volatile organic solvents and with no need for column chromatographic separation for most cases.

Micro-voids defects associated with materials formed by diffusion bonding and super-plastic connection limit their usage in the aerospace industry. A crystal plasticity finite element (CPFE) model was established in the current work to investigate the relationship between local stress concentration and the micro-void defects, and predict the fatigue crack initiation lifetime. Based on the concept of the curvature of the crack tip, the shape and size of the voids are strictly separated, so that the influence of the single parameter of voids on the microplasticity deformation behavior is better obtained. It's found that the micro-voids lead to the stress concentration phenomenon in the material, the effect of the curvature of the void tip surface is greater than that of the void size. Stress concentration tends to occur in the hard grains. When L/d is greater than 2.0, stress concentration factor reaches a constant small value. The simulated results based on the Manson-Collin law and Fatemi-Socie parameter show that when the void tip curvature is greater than 0.4 μm−1 or L/d is less than 2.0, the fatigue crack initiation lifetime is less than 106 cycles, indicating that the influence of such micro-voids on fatigue crack initiation is small. This work has a good guiding significance for properties and lifetime prediction of the material with defects.

Cold dwell fatigue of titanium alloys used in aero-engine components has threatened flight safety for over five decades. This phenomenon was encountered in Al-containing titanium alloys, occurring at relatively low temperatures, where load hold at applied peak stress result in reduction in number of cycles by an order of magnitude or more (the so-called dwell debit). The present paper reviews the recent advances in dwell-fatigue of titanium alloys with the primary motivation being to understand the dwell-fatigue damage mechanism relating microstructural configurations, dislocations and local strain rate sensitivity. Numerous studies have focused on the identification of fatigue-critical microstructural configurations, such as microtextured regions, rogue grain pairs and (0001) twist grain boundaries. As an example of dwell resistant alloy design, Timetal 575 is a candidate alloy for aero-engine fan disc applications with both superior static and cyclic strengths and low dwell sensitivity.

Abstract Background Bacillus subtilis, an important industrial microorganism, is commonly used in the production of industrial enzymes. Genome modification is often necessary to improve the production performance of cell. The dual-plasmid CRISPR-Cas9 system suitable for iterative genome editing has been applied in Bacillus subtilis. However, it is limited by the selection of knockout genes, long editing cycle and instability. Results To address these problems, we constructed an all-in-one plasmid CRISPR-Cas9 system, which was suitable for iterative genome editing of B. subtilis. The PEG4000-assisted monomer plasmid ligation (PAMPL) method greatly improved the transformation efficiency of B. subtilis SCK6. Self-targeting sgRNArep transcription was tightly controlled by rigorous promoter PacoR, which could induce the elimination of plasmids after genome editing and prepare for next round of genome editing. Our system achieved 100% efficiency for single gene deletions and point mutations, 96% efficiency for gene insertions, and at least 90% efficiency for plasmid curing. As a proof of concept, two extracellular protease genes epr and bpr were continuously knocked out using this system, and it only took 2.5 days to complete one round of genome editing. The engineering strain was used to express Douchi fibrinolytic enzyme DFE27, and its extracellular enzyme activity reached 159.5 FU/mL. Conclusions We developed and applied a rapid all-in-one plasmid CRISPR-Cas9 system for iterative genome editing in B. subtilis, which required only one plasmid transformation and curing, and accelerated the cycle of genome editing. To the best of our knowledge, this is the rapidest iterative genome editing system for B. subtilis. We hope that the system can be used to reconstruct the B. subtilis cell factory for the production of various biological molecules.

As Ti-70 is a new type of marine titanium alloy, research on the recrystallization process of its sheet is necessary. This article studies the effects of different temperatures and times of annealing on the recrystallization process of 5.0 mm thick Ti-70 titanium alloy cold-rolled sheets by metallographic analyses and hardness tests. The results show that after 30 min of annealing at 620~700 °C, the recrystallization process was mostly complete, and uniform and equiaxed recrystallized grains could be obtained. The recrystallization process starts after 8 min of annealing at 700 °C, and after holding for 15~30 min, the recrystallization process is almost complete and the grain size is about 8.2 μm. The recrystallization activation energy of a Ti-70 titanium alloy cold-rolled sheet is Qr = 11.0645 × 104 J/mol. The ultimate tensile strength (Rm) can be controlled between 705 and 852 MPa, the yield strength (Rp0.2) can be controlled between approximately 623 and 793 MPa, and the elongation percentage (A) can be controlled between approximately 10.0 and 25.0% after rolling and heat treatment of Ti-70 alloy sheets.

Interfacial β0 phase strengthening on the creep properties of TNM alloy has been investigated. The initial fully lamellar microstructure with fine-dispersed interfacial β0 phase was fabricated by powder hot isostatic pressing (P-HIP) and then carried out ageing treatment. The results indicated that the aged condition presented better microstructural stability and excellent creep resistance than the P-HIPed condition. Moreover, the ω phase precipitated within the β0 phase by stress-inducing. The β0/β0(ω) phase was not only effectively restricted the dislocation motion, twins and stacking faults propagation, but also delayed the α2 lamellae decomposition to maintain the integrity of the fully lamellar structure.

Microstructure degradation of a fully lamellar TNM alloy during creep has been investigated by using the quasi-in-situ creep tests, which were conducted at 750 °C under 250 MPa, for (1–5.4) % creep strain. The results indicated that the fully lamellar structure exhibited gradual microstructure degradation during creep. At the primary creep region, dynamic recrystallization of the γ phase occurred at the colony boundary and a massive proportion phase transformation occurred, these caused microstructure instability and a relatively large primary strain. Within the steady-state creep region, the steady creep strain rate was 8.89E-8 s−1. The fine (α2+γ) clusters with more interface provided obstacles for the dislocation movement because of α2 parallel decomposition. Moreover, the interfacial β0 phase precipitation was suppressed the α2 → γ transformation and remained the integrity and continuity of the lamellae structure, which was attributed to the steady-state creep resistance. At the tertiary creep region, many cavities nucleated at the colony boundary or γg/β0 phase boundaries due to the local stress concentration. The dynamic recrystallized of the γg area was extended and damaged the integrity of the fully lamellar structure. Moreover, the partial dissolution of α2 lamellae caused discontinuous lamellae and reduced the creep resistance. It concluded that microstructure stability has a strong influence on creep resistance.

Occupational stress, cumulative fatigue, and work-related musculoskeletal disorders (WMSDs) are major concerns in the field of occupational health. Previous studies on occupational health focused on key industries, such as medical care, while there were few related studies on Information Technology (IT) industry. Our study explored the factors influencing occupational stress, cumulative fatigue, and musculoskeletal disorders in the IT industry. We collected 1363 IT workers’ valid questionnaires, of which 73.1% of participants were technicians in Chongqing, 2021. The core occupational stress scale (COSS), self-diagnosis checklist for the assessment of workers’ accumulated fatigue and Chinese musculoskeletal disorders questionnaire were used to measure the occupational stress, cumulative fatigue, and musculoskeletal disorders of the respondents. Logistic regressions were used to explore the correlated factors affecting these indicators. The results showed that the prevalence of occupational stress, cumulative fatigue, and musculoskeletal disorders was 50.4%, 47%, and 72.3%, respectively. Working in the current position for 3–10 years was a common increased risk for all three indicators. Insomnia was associated with an increased risk of cumulative fatigue (Odds Ratio, OR = 2.156, p < 0.001) and musculoskeletal disorders (OR = 1.878, p < 0.001). Cumulative fatigue was also associated with an increased risk of having WMSDs (OR = 3.207, p < 0.001). According to our findings, occupational factors, such as long working years, overtime work, and personal lifestyle, are highly related to the occurrence of occupational stress, cumulative fatigue, and musculoskeletal disorders for IT industry workers. More attention should be paid to women and those with long working hours in the IT industry.

The forest fuel load influences the spreading rate and fire intensity during a forest fire. However, the mechanism of environmental filtering and dispersal limitation that affects the spatial distribution of the forest fuel load remains unclear. In this study, live (tree, herbaceous, and shrub) and dead fuel loads (litter and humus) were estimated based on the plot investigation results of 4 typical stands (Pinus massoniana, Platycladus orientalis, Ficus microcarpa, and Cinnamomum camphora) in Chongqing, China. The results demonstrated that the tree, shrub, herbaceous, litter, and humus fuel loads of the 4 typical stands were 66.92 to 118.54 Mg/ha, 2.93 to 4.04 Mg/ha, 0.77 to 1.01 Mg/ha, 0.90 to 1.39 Mg/ha, and 1.49 to 1.98 Mg/ha, respectively. The forest fuel load varied significantly among the different stands. The Mantel test revealed that the forest fuel load had significantly positive correlations with the geospatial distance and stand environment but no significant correlation with the topographic factor. Additionally, the redundancy analysis demonstrated that the stand factors, canopy density and average canopy height, and the topographic factor, altitude, had significant impacts on the forest fuel load. The variance partitioning analysis revealed that the spatial heterogeneity of the forest fuel load was mainly attributed to the covariation of environmental and spatial factors (29.55%). Moreover, the geospatial distance was a dominant independent factor for the fuel distribution (14.66%), followed by the stand environment (9.51%) and topographic factor (0.35%). In summary, the spatial distribution of the forest fuel load was dependent on niche-based and random processes, and dispersal limitation was the dominant factor.

The microstructural and crystallographic features of the β phase in TNM alloy during the hot extrusion at 1290 °C and the subsequent cooling process were investigated. Except the original grain boundary β phase, two categories of β particles, along grain boundaries of primarily recrystallized α grains (intergranular β) and in grain interiors of abnormally grown α grains (intragranular β), were found in the extruded microstructure. The former obeyed the Burgers orientation relationship with, at least, one of the neighboring α grains, whereas the latter did not show any specific orientation relationship with the α host. Analysis revealed that the thermally-induced α→β phase transformation interweaving with the abnormal α grain growth happened during the transition period from end-extrusion to water-quenching. The intergranular β particles were derived from the thermally-induced α→β phase transformation, and the intragranular β particles were resulted from the intergranular β precipitates after being swallowed by the abnormally grown α grains. The present work provides new information of thermally-induced phase transformation by adiabatic heating and the annexation of the second phase by abnormal grain growth during high-speed hot deformation.

The reasonable design and application of phase transformation is an efficient approach to coordinate the microstructure and properties of alloys. The sequence of compositional and structural transformation determines the type and mechanism of phase transformation. Because of their low density and excellent high-temperature properties, TiAl alloys that contain fully lamellar microstructure have been applied to low-pressure turbine engine blades. However, there is no consensus on the mechanism of lamellar formation. Here, we propose a new mechanism that is dominated by spinodal decomposition, in which compositional transformation occurs prior to structural transformation during lamellar formation. Transitional lamellae with fcc-based long-period superstructures are introduced to prove the mechanism of sequentially spinodal decomposition, shear transformation, compositional modulation and ordering.

Ti-44.5Al-3.8Nb-1Mo-0.2B alloy (TNM) sheets were prepared by hot rolling, and the effect of the initial microstructure on the process was discussed in this work. The as-received TNM alloy billets with nearly and fully lamellar structures were prepared by forging and casting processes (named M1 and M2), respectively. For the as-rolled sheets from M1, the fraction of recrystallization increased gradually with the decrease of reduction per pass based on GOS analysis. Compared with M1, M2 required a larger deformation to achieve complete recrystallization. Meanwhile, the as-rolled sheets from M2 possessed a smaller grain size than that from M1. In addition, the γ-DRX behavior during the multi-pass hot rolling was discussed, and the DDRX was found to play the dominant role in this process. The phase transformation of β/β0 → α occurred in the 1200 °C rolling process. It was presumed that this transformation was promoted by increasing the rolling temperature, therefore, the volume fraction of the β0 phase decreased. The α2 lath decomposed gradually with the increasing of rolling temperature from 1200 °C to 1250 °C, simultaneously, the combination of the adjacent γ laths resulted in the coarsening of γ lath.

The simultaneous optimization of competing properties is a challenge of machine learning based materials design. We proposed a domain knowledge constrained active learning loop for the design of high entropy alloys with optimized strength and ductility, by narrowing down the unexplored space using the valence electron concentration criterion. The active learning loop iterated six times and one alloy with an ultimate strength of 1258 MPa and an elongation of 17.3 % was synthesized. To uncover the underlying mechanism for synergetic optimization, we characterized the phase structure and eutectic microstructure, and discussed the possible origins from the view of strain hardening and crack initiation. The proposed framework that combines domain knowledge with machine learning can facilitate the design of target materials with coordinating optimization of competing properties.

The microscopic deformation behavior of Inconel 625 superalloy has been investigated by means of nanoindentation experiments and crystal plasticity finite element simulations. Based on the electron backscattered diffraction characterizations, the nanoindentation simulations were performed on grains with various orientations. The simulated load–displacement curves match well with those of experiment and the maximum difference in materials hardness between the experimental and the simulation result is about 6.86%, which is within the accuracy of the model. Moreover, surface Schmid factor (SSF) and interior Schmid factor (ISF) were proposed out and the scanning electron microscope and atomic force microscope characterizations were carried out. The results show that the pile-up tends to occur at the locations with a large SSF. Subsequently, the simulations of nanoindentation on [001]-, [011]-, and [111]-oriented grains were performed by the established model. It is revealed that the residual topography changes periodically when the indenter is fixed and the crystal only rotates around the Z-axis of the sample coordinate system. Combining with the analysis of the ISF, this periodicity of residual topography reflects the superimposed effect of the slip systems, and a large ISF promotes the in-plane displacement of the interior material which inhibiting the evolution of pile-up, while a small ISF leads to a high pile-up.

A series of ultra-toughened sustainable blends were prepared from poly(lactic acid) (PLA) and bromobutyl rubber-based ionomers (i-BIIRs) via reactive blending, in which dicumyl peroxide (DCP) and Joncryl®ADR-4440 (ADR) were used as reactive blending additives. The miscibility, phase morphology and mechanical property of the PLA/i-BIIRs blends were thoroughly investigated through DMA, SEM, tensile and impact tests. The influence of different ionic groups and the effects of DCP and ADR on the compatibility between the phases, phase structure and mechanical properties were analyzed. The introduction of the imidazolium-based ionic groups and the reactive agents enable the i-BIIRs play multiple roles as effective compatibilizers and toughening agents, leading to improved interfacial compatibility and high toughness of the blends. The mechanical properties test showed that the PLA/i-BIIRs blends exhibit excellent toughness: impact strength and the elongation at break of AR-OH(30)+AD reached 95 kJ/m2 and 286%, respectively. The impact fracture surface showed the large-scale plastic deformation of the PLA matrix in the blends, resulting in greatly absorbing the impact energy. The results proved that simultaneously applying reactive blend and multiple intermolecular interactions methods is an effective toughening strategy for toughening modification of the PLA blends.

In the present work, the adiabatic shear characteristics of our recently designed α + β dual-phase Ti alloy at different strain rates have been investigated by hat shaped specimen. The deformation process is divided into three stages: work hardening stage, steady stage, and unstable thermal softening stage. Along or near the shear deformation paths, the microvoids and the cracks can be captured at the strain rate of 1.8 × 104 s−1, 2.0 × 104 s−1, and 2.3 × 104 s−1, both of which contribute to the stable and unstable softening. It is found that dynamic stored energy of cold work will be significantly improved by the enhanced high strain rate. In the view of coupling analysis of inverse pole figure and grain boundary map, it seems that low angle grain boundaries present a good resistance to the formation of cracks and thermal softening. On the contrary, high angles grain boundaries are typically located in ASBs and their affecting regions, which is in line with the reported results. While the geometrical necessary dislocation (GND) density of adiabatic shear band (ASB) and its surroundings increased significantly, the width of the ASB becomes wider as the strain rate increases, which is consistent with the theory of sub-grain rotation dynamic recrystallization model. The formation of multiple ASBs in the corner position is schematically illustrated and the average elastic modulus and hardness of the ASB region are lower than the α and β phases, combined with the GND analysis, which proves that the ASB is a thermal softening zone in this experiment.

A data identifier (DID) is an essential tag or label in all kinds of databases—particularly those related to integrated computational materials engineering (ICME), inheritable integrated intelligent manufacturing (I3M), and the Industrial Internet of Things. With the guidance and quick acceleration of the development of advanced materials, as envisioned by official documents worldwide, more investigations are required to construct relative numerical standards for material informatics. This work proposes a universal DID format consisting of a set of build chains, which aligns with the classical form of identifier in both international and national standards, such as ISO/IEC 29168-1:2000, GB/T 27766–2011, GA/T 543.2–2011, GM/T 0006–2012, GJB 7365–2011, SL 325–2014, SL 607–2018, WS 363.2–2011, and QX/T 39–2005. Each build chain is made up of capital letters and numbers, with no symbols. Moreover, the total length of each build chain is not restricted, which follows the formation of the Universal Coded Character Set in the international standard of ISO/IEC 10646. Based on these rules, the proposed DID is flexible and convenient for extending and sharing in and between various cloud-based platforms. Accordingly, classical two-dimensional (2D) codes, including the Hanxin Code, Lots Perception Matrix (LP) Code, Quick Response (QR) code, Grid Matrix (GM) code, and Data Matrix (DM) Code, can be constructed and precisely recognized and/or decoded by either smart phones or specific machines. By utilizing these 2D codes as the fingerprints of a set of data linked with its cloud-based platforms, progress and updates in the composition–processing–structure–property–performance workflow process can be tracked spontaneously, paving a path to accelerate the discovery and manufacture of advanced materials and enhance research productivity, performance, and collaboration.

The nonlocal crystal plasticity finite element (CPFE) simulations and extreme value statistics were combined to study the effects of microstructure on the high cycle fatigue (HCF) behavior of dual-phase Ti alloy. A modified Armstrong-Frederick nonlinear kinematic hardening equation accounting for cyclic softening effect was employed in the crystal plasticity constitutive model. Three-dimensional equiaxed microstructure models and two-dimensional duplex microstructure models with real lamellar structure were generated based on Voronoi method, serving as statistical volume elements (SVEs). The effects of morphological and crystallographic features, including grain size, grain orientation, phase volume fraction and lamellae width, on the fatigue performance were investigated. By simulating multiple SVEs, extreme value distributions of the driving force for fatigue crack formation were predicted using Fatemi-Socie (FS) parameter as a fatigue indicator parameter (FIP). Meanwhile, whether the extreme values of geometrically necessary dislocation (GND) density can be taken as a FIP was discussed with compared to FS FIP. The GND density, related to local stress and strain gradient, has considerable potential as a FIP to estimate the fatigue performance of titanium alloys. Based on simulated results, it is suggested that microstructure with small grain size, low volume fraction of primary α grains, and thinner α lamellae width have the lowest probability of crack formation during HCF.

A crystal plasticity finite element (CPFE) model has been developed to study the microplasticity behavior of Ti-5553 alloy with equiaxed dual-phase microstructure under high-cycle fatigue (HCF) loading process. The microstructure and density distributions of geometrically necessary dislocations (GNDs) after HCF loading were characterized by electron backscattered diffraction (EBSD). Experimental results show that the microplasticity accumulation behavior happens in α phase during the HCF loading process. The developed CPFE model captures the essential physics of microplasticity accumulation in the primary α phase and stress concentration at the softer α/β interface. Besides, the effect of stress levels and volume fraction of primary α phase on microplasticity behavior was discussed. Results indicate that the stress concentration can be taken as fatigue indicator parameter (FIP) for high stress level HCF loading conditions, while the cumulative shear strain can be taken as FIP for low volume fraction of primary α phase conditions. This work provides a strategy not only contributing to understand the microplasticity behavior during HCF loading process but also choosing a suitable FIP for different loading conditions and microstructure states. Keywords: Microplasticity, Crystal plasticity model, High-cycle fatigue, Titanium alloy

Nitrogen(N) enrichment changes the community structure of terrestrial ecosystems. However, the patterns and structural functions of species interaction networks under N-enrichment conditions are still unclear. We compared and analysed data from 13 years of N deposition experiments in the Inner Mongolia temperate steppe in China. We found that spatial association effectively detected intransitive networks, the structure of which was occasionally changed by species with low biomass but high-frequency occurrence, as an especially vital intermediary for forming a large network. The peak value of the network complexity was maintained at 2 gNm-2⁢year-1. In the third year after fertilization at 50 gNm-2⁢year-1, the species interaction changed to transitivity, which lasted for 8 years. Then, the environment completely replaced species interactions as the main factor affecting community composition. Surprisingly, the negative effect of N enrichment on the species network was counteracted by mowing and precipitation, which increased the probability of intransitive network formation. In the intransitive network, species diversity was not only maintained but also increased under low N-addition rates from 0 gNm-2⁢year-1 to 3 gNm-2⁢year-1. These studies indicated that N enrichment reduced the complexity of the species network and increased hierarchical differences among species competition. Intransitive competition is highly prevalent and a key driver of species coexistence and diversity maintenance in the typical steppe. Moreover, environmental factors directly affect plant intransitive competition, resulting in changes in species diversity.

Aerated drip irrigation is rendered as a new water-saving irrigation method based on drip irrigation technology, which is endowed with the function of effectively alleviating the problem of rhizosphere hypoxia in crop soil, enhancing the utilization rate of water and fertilizer; as a result, it improves the harvest and quality of crops. However, clogged emitters are important indexes, among others, that pose an influence to the service effect and life duration of drip irrigation systems. At present, the working principle and mechanism of the influence of air feeding on the blockage of drip irrigation emitters remain unclear. Therefore, based on the two gas filling methods of the micro/nano bubble generator and Venturi injector, the dynamic change process for the average flow ratio of an air-filled drip irrigation emitter was studied by the method of emitter plugging test. 16S rRNA sequencing was used to analyze the microbial diversity of the emitter plugs. The results show that the air injection can pose influence on the clogging procedure of drip irrigation emitters, and more importantly, it makes the distribution of blocked emitters more uniform, thus improving the uniformity of the system. Different filling methods have different effects on the blockage of the emitter. Among them, the blockage time of drip irrigation system under the micro/nano aerated drip irrigation (MAI) mode is 5.73 times longer than that under unaerated drip irrigation (UVI), and similarly, Venturi gas drip irrigation (VAI) is close to that under UVI. The filling method changed the microbial diversity of the blockage in the emitter. Among them, the number of operational taxonomic unit (OTU) unique to MAI was 2.1 times that of UVI, and the number of OTU unique to VAI was 1.3 times that of UVI. Meanwhile, gas addition will inhibit the growth of Nitrospirae and Proteobacteria microbial communities and promote the growth of Firmicutes and Actinobacteria microbial communities. Furthermore, the increase in microbial extracellular polymer in the plugging material of the emitter was inhibited and the plugging process of the emitter was slowed down. The research results are of great significance in the disclosure of the clogging mechanism of drip irrigation emitter and constructing the green, anti-blockage technology of aerated drip irrigation.

This paper proposes a brain-inspired navigation model based on absolute heading for the autonomous navigation of unmanned platforms. The proposed model combined the sand ant’s strategy of acquiring absolute heading from the sky environment and the brain-inspired navigation system, which is closer to the navigation mechanism of migratory animals. Firstly, a brain-inspired grid cell network model and an absolute heading-based head-direction cell network model were constructed based on the continuous attractor network (CAN). Then, an absolute heading-based environmental vision template was constructed using the line scan intensity distribution curve, and the path integration error was corrected using the environmental vision template. Finally, a topological cognitive node was constructed according to the grid cell, the head direction cell, the environmental visual template, the absolute heading information, and the position information. Numerous topological nodes formed the absolute heading-based topological map. The model is a topological navigation method not limited to strict geometric space scale, and its position and absolute heading are decoupled. The experimental results showed that the proposed model is superior to the other methods in terms of the accuracy of visual template recognition, as well as the accuracy and topology consistency of the constructed environment topology map.

Ti-4Al-5Mo-5V-5Cr-1Nb (wt.%) is a new type of high-strength (~1300 MPa) titanium (Ti) alloy developed for aerospace applications. Until now, the research on its welding and subsequent heat treatment is barren. Herein, we employed electron beam welding (EBW) to a solutionized Ti-4Al-5Mo-5V-5Cr-1Nb with a phase constituent of α + β and investigated its microstructure and mechanical properties in both as-welded (AW) and post-weld aging treated (PWAT) conditions. Results showed that due to the thermal input of the welding process, the α phase in the original microstructure of base material (BM) transformed into the β phase in the fusion zone (FZ). Similar microstructural evolution was observed for the heat-affected zone (HAZ) near the FZ (Near-HAZ), whereas the HAZ far away from FZ (Far-HAZ) contained a small amount of round α phase (ghost α) due to its slower cooling rate. Such a microstructural change resulted in poor tensile strength (~780 Mpa) for the as-welded joint. After PWAT, a large number of acicular α precipitated in the FZ and HAZ and its size (S) in different zones followed the order of SFar-HAZ < SFZ ≈ SNear-HAZ < SBM. The presence of αs precipitates remedied the tensile strength of the weld joint almost to the same as that of the BM. The present findings established the foundation of the application of this high-strength Ti alloy.