Ti750s titanium alloy,a novel high-temperature titanium alloy designed for short-term service at elevated temperatures(700–750℃),has previously lacked comprehensive understanding of its hot processing behavior.In th...Ti750s titanium alloy,a novel high-temperature titanium alloy designed for short-term service at elevated temperatures(700–750℃),has previously lacked comprehensive understanding of its hot processing behavior.In this study,the high-temperature deformation behavior and microstructural evolution of the Ti750s alloy were systematically investigated through thermal simulation compression tests conducted at temperatures ranging from 900 to 1070℃and strain rates between 0.1 and 10 s⁻1.A hot processing map was constructed using the dynamic material model to optimize the hot processing parameters.The results indicated that the optimal processing window was between 1040 and 1070℃with a strain rate of 0.1 s⁻1.Processing within the instability region resulted in localized plastic deformation,manifesting as pronounced shear bands and a highly heterogeneous strain distribution;this region should be avoided during hot deformation.Within theα+βphase safety zone characterized by low power dissipation rates between 0.32 and 0.4,the primary deformation mechanism in this region was dynamic recovery(DRV),where the lamellarαgrains underwent deformation and rotation.Conversely,in theα+βphase safety zone with high-power dissipation rates between 0.45 and 0.52,dynamic spheroidization of theαphase and dynamic recrystallization(DRX)of theβphase occurred concurrently.In theβphase safety zone with low power dissipation rates between 0.32 and 0.51,the primary deformation mechanism consisted of DRV ofβgrains,accompanied by limited DRX.However,in theβphase safety zone with high-power dissipation rates exceeding 0.56,both DRV and DRX ofβgrains took place,resulted in a significant increase in the size and number of recrystallized grains compared to those observed under low power dissipation conditions.展开更多
The high melting point element W and the rare earth element Ce were added to 18Cr-Mo(444-type)ferritic stainless steel to improve its high-temperature oxidation resistance in exhaust gas.A simulated exhaust gas was fi...The high melting point element W and the rare earth element Ce were added to 18Cr-Mo(444-type)ferritic stainless steel to improve its high-temperature oxidation resistance in exhaust gas.A simulated exhaust gas was filled in the simultaneous thermal analyzer to simulate the service environment,and the oxidation behavior in high-temperature exhaust gas environment of 444-type ferritic stainless steel alloyed with W and Ce was investigated.The oxide structure and composition formed in this process were analyzed and characterized by scanning electron microscopy/energy-dispersive spectroscopy and electron probe analysis,and the mechanism of W and Ce in the oxidation process was revealed.The results show that 18Cr-Mo ferritic stainless steel containing W and Ce has better oxidation resistance in high-temperature exhaust gas.The element W can promote the precipitation of Laves phase at the matrix/interface,inhibit the interface diffusion of oxidizing elements and prevent the inward growth of the oxide film.The element Ce can suppress the volume of SiO_(2)at the oxide film/interface,reducing the breakaway oxidation caused by cracking of the oxide film.The CeO_(2)provides nucleation sites for oxide particles,promoting the healing of cracks and voids within the oxide film.展开更多
This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standar...This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standard system was established for comprehensive quality evaluation of HTD.There were obvious changes in the physicochemical properties,enzyme activities,and volatile flavor components at different storage periods,which affected the sensory evaluation of HTD to a certain extent.The results of high-throughput sequencing revealed significant microbial diversity,and showed that the bacterial community changed significantly more than did the fungal community.During the storage process,the dominant bacterial genera were Kroppenstedtia and Thermoascus.The correlation between dominant microorganisms and quality indicators highlighted their role in HTD quality.Lactococcus,Candida,Pichia,Paecilomyces,and protease activity played a crucial role in the formation of isovaleraldehyde.Acidic protease activity had the greatest impact on the microbial community.Moisture promoted isobutyric acid generation.Furthermore,the comprehensive quality evaluation standard system was established by the entropy weight method combined with multi-factor fuzzy mathematics.Consequently,this study provides innovative insights for comprehensive quality evaluation of HTD during storage and establishes a groundwork for scientific and rational storage of HTD and quality control of sauce-flavor Baijiu.展开更多
Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temper...Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.展开更多
The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(S...The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.展开更多
Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose har...Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose hardness is 65 HRC and flexural strength is 1450 MPa.The high-temperature oxidation mechanism of TiC-based cermets was investigated through an X-ray diffractometer and scanning electron microscope.The added elements Ni and Cr along with their solid solutions not only bond with the hard phase TiC to ensure the physical performance of the cermet,but also impede the internal diffusion during oxidation by forming a dense composite oxide layer,thereby enhancing the oxidation resistance.The TiC-NiCr cermet exhibits a dense protective oxide layer at 900℃ and can endure continuous oxidation for approximately 1000 h.A methodology for fabricating TiC-NiCr metal matrix composites is proposed,and their oxidation resistance is evaluated,providing a theoretical and practical basis for simultaneously enhancing the mechanical properties and oxidation resistance and reducing production costs.展开更多
(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co co...(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co content on microstructure and mechanical properties were investigated.The results indicate that the grain size of the alloy decreases with increasing the Co content.In the as-cast state,the alloy consists primarily of the B19′phase,with a trace of B2 phase.The fracture morphology is predominantly composed of the B19′phase,whereas the B2 phase is nearly absent.Increasing the Co content or reducing the sample dimensions(d)markedly enhance the compressive strength and ductility of the alloy.When d=2 mm,the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy demonstrates the optimal mechanical properties,achieving a compressive strength of 2142.39±1.8 MPa and a plasticity of 17.31±0.3%.The compressive cyclic test shows that with increasing the compressive strain,the residual strain of the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy increases while the recovery ability declines.The superelastic recovery capability of the alloy is continuously enhanced.The superelastic recovery rate increases from 1.36%to 2.12%,the residual strain rate rises from 1.79%to 5.52%,the elastic recovery rate ascends from 3.86%to 7.36%,while the total recovery rate declines from 74.48%to 63.20%.展开更多
In this study,the oxidation behavior of Ti42Al5Mn,Ti42Al5Mn0.5 W,Ti42Al5Mn0.5W0.1B,and Ti42Al5Mn0.8 W was investigated at 800℃.Due to the inability to form a dense protective Al2O_(3) layer,Ti42Al5Mn suffered severe ...In this study,the oxidation behavior of Ti42Al5Mn,Ti42Al5Mn0.5 W,Ti42Al5Mn0.5W0.1B,and Ti42Al5Mn0.8 W was investigated at 800℃.Due to the inability to form a dense protective Al2O_(3) layer,Ti42Al5Mn suffered severe spallation during oxidation at 800℃and the mass gain was significant.The intermediate layer between the scale and the substrate was first composed of Laves/Z phase but changed toα2/Z phase with prolonged oxidation.The intermediate layer with high Ti/Al ratio favors the forma-tion of a thick Al2O_(3)+TiO_(2) mixed layer in the oxide scale which is prone to initiate cracks and cause the spalling of oxides.The doping of W in TiO_(2) effectively inhibited its generation and promoted the for-mation of a dense Al2O_(3) layer,resulting in a significant improvement in the oxidation resistance of the alloy.Compared to Ti42Al5Mn alloy,Ti42Al5Mn0.8 W showed no spallation after 300 h cyclic oxidation and the kinetic curve changed from liner law to parabolic law.The intermediate layer of Ti42Al5Mn0.8 W alloy was composed of a single Laves phase and remained unchanged even after 1000 h oxidation at 800℃,offering a favorable basis for the generation of a stable protective oxide layer in the alloy.The addi-tion of 0.1 at.%B to Ti42Al5Mn0.5 W alloy refined its microstructure and further improved its spallation resistance to a level close to that of Ti42Al5Mn0.8 W alloy.展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
The tensile strength of rocks under real-time high-temperatures is essential for enhanced geothermal system development.However,the complex occurrence and deep burial of hot dry rocks limit the quantity and quality of...The tensile strength of rocks under real-time high-temperatures is essential for enhanced geothermal system development.However,the complex occurrence and deep burial of hot dry rocks limit the quantity and quality of standard samples for mechanical testing.This paper compared the tensile strengths obtained from Brazilian splitting tests on standard samples(with a diameter of 50 mm and a thickness of 25 mm)and micro-tensile samples(with a diameter of 50 mm and a thickness of 25 mm)of two types of granites.A power-law size effect model was established between the two sets of data,validating the reliability of the testing method.Then,miniature Brazilian splitting under real-time high-temperature,combined with X-ray diffraction(XRD)revealed temperature-dependent strength variations and microstructural damage mechanisms.The results show that:(1)The comparison error between the tensile strength obtained by the fitting model and that of the measured standard samples was less than 6%.(2)In real-time high-temperature conditions,tensile strength of granite exhibited non-monotonic behavior,increasing below 300°C before decreasing,with sharp declines at 400–500°C and 600–700°C.(3)Thermal damage stems from the differences in the high-temperature behavior of minerals,including dehydration,phase transformation,and differential expansion.展开更多
With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components ope...With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components operating in high-temperature environments within the aerospace sector.However,typical high-temperature coatings currently face challenges in effectively integrating excellent oxidation resistance,wear resistance,and lubrication properties in high-temperature settings.Studies have demonstrated the significant potential of Transition Metal Dichalcogenides(TMDCs)as lubricant additives in high-temperature lubrication,attributable to their distinctive crystal structures.Thus,this review concentrates on the compositional design of individual MX_(2)-type(M=W,Mo,Nb,Ta;X=S,Se)TMDCs(molybdenum disulfide(MoS_(2)),tungsten disulfide(WS2),niobium diselenide(NbSe_(2)),molybdenum diselenide(MoSe_(2)),tungsten diselenide(WSe_(2)))and their composites,including inorganic oxygen-containing sulfides,and explores the utilization of TMDCs in self-lubricating coatings.Furthermore,conventional preparation methods(mechanical exfoliation,liquid-phase ultrasonic exfoliation,chemical vapour deposition)for synthesizing TMDCs are outlined.Finally,an analysis of the lubrication mechanism of MX_(2)-type TMDCs is provided,along with future directions for enhancing the high-temperature lubrication performance of composite coatings.展开更多
Investigating highly effective electrocatalysts for high-temperature proton exchange membrane fuel cells(HT-PEMFC)requires the resistance to phosphate acid(PA)poisoning at cathodic oxygen reduction reaction(ORR).Recen...Investigating highly effective electrocatalysts for high-temperature proton exchange membrane fuel cells(HT-PEMFC)requires the resistance to phosphate acid(PA)poisoning at cathodic oxygen reduction reaction(ORR).Recent advancements in catalysts have focused on alleviating phosphoric anion adsorption on Pt-based catalysts with modified electronic structure or catalytic interface and developing Fe-N-C based catalysts with immunity of PA poisoning.Fe-N-C-based catalysts have emerged as promising alternatives to Pt-based catalysts,offering significant potential to overcome the characteristic adsorption of phosphate anion on Pt.An overview of these developments provides insights into catalytic mechanisms and facilitates the design of more efficient catalysts.This review begins with an exploration of basic poisoning principles,followed by a critical summary of characterization techniques employed to identified the underlying mechanism of poisoning effect.Attention is then directed to endeavors aimed at enhancing the HT-PEMFC performance by well-designed catalysts.Finally,the opportunities and challenges in developing the anti-PA poisoning strategy and practical HT-PEMFC is discussed.Through these discussions,a comprehensive understanding of PA-poisoning bottlenecks and inspire future research directions is aim to provided.展开更多
The Al-Cu alloy is a historical model alloy system in the physical metallurgy of engineering aluminum al-loys.Nevertheless,a few fundamental phenomena of phase transformation occurring in this simple alloy are still n...The Al-Cu alloy is a historical model alloy system in the physical metallurgy of engineering aluminum al-loys.Nevertheless,a few fundamental phenomena of phase transformation occurring in this simple alloy are still not adequately understood.Among all,for instance,the formation mechanisms of its key harden-ingθ'-phase remain mysterious.There is strong evidence thatθ'-precipitates can form from a different high-temperature precipitation pathway,while their formation mechanism via the conventional pathway well-known since 1938 remains to be clarified.Using state-of-the-art electron microscopy,here we report a secondary high-temperature precipitation pathway ofθ'-precipitates.It is demonstrated that led by a secondary high-temperature precursor,namedθ'_(S-HTP),very fineθ'-precipitates can form in the unde-formed bulk Al-Cu alloys at elevated temperatures(≥250℃).Interestingly is that with Sc-microalloying the surviving rate of meta-stableθ'_(S-HTP) precipitates increases drastically and the formedθ'-precipitates become much finer,significantly enhancing the alloys’strength and thermal stability.It is also revealed that aθ'_(S-HTP) precipitate can genetically evolve into aθ'-precipitate without having to change its mor-phology and orientation.Our study provides new insights into understanding the industry bulk alloys’microstructures and properties.展开更多
Considering the fracture problem of the silica-based ceramic core in the integrated casting of hollow turbine blades during directional solidification,the influence of various whiskers,including silicon carbide whiske...Considering the fracture problem of the silica-based ceramic core in the integrated casting of hollow turbine blades during directional solidification,the influence of various whiskers,including silicon carbide whiskers,silicon nitride whiskers,and mullite whiskers,on the high-temperature strength of the silica-based ceramic core was investigated.Additionally,the formation of microstructure morphology and phase structure was analyzed.Research results show that silicon carbide whiskers can reduce the microcracks caused by the shrinkage of cristobalite.During the sintering process,some of the silicon carbide whiskers oxidize and react with aluminum powder to form mullite,which can improve the high-temperature strength of the ceramic cores.When the content of silicon carbide whiskers is 3wt.%,the high-temperature bending strength of the cores reaches the maximum value of 21 MPa.Silicon nitride whiskers decompose in a high-temperature environment and react with aluminum powder in the matrix material to form mullite whiskers.When the content of silicon nitride whiskers is 5wt.%,the high-temperature bending strength of the cores reaches 20 MPa.By adding mullite whiskers,a structure of cristobalite wrapped mullite whiskers can be formed to achieve toughening.When the content of mullite whiskers is 4wt.%,the high-temperature bending strength can reach 17.2 MPa.By comparing the performance of silicon carbide whiskers,silicon nitride whiskers,and mullite whiskers,along with conducting slurry viscosity tests and casting experiments,it is determined that a ceramic slurry containing 4wt.%mullite whiskers is the most suitable for making the cores used in the integrated casting of hollow turbine blades.展开更多
The launch of International Thermonuclear Experimental Reactor project paves the way to wide adoption of DT fusion energy as future energy source.Efficient fuel cycle to minimize strategic tritium inventory proves cru...The launch of International Thermonuclear Experimental Reactor project paves the way to wide adoption of DT fusion energy as future energy source.Efficient fuel cycle to minimize strategic tritium inventory proves crucial for commercially viable fusion technologies.ZrCo alloy is considered as a promising candidate for fast isotope handling.However,cycling degradation caused by hydrogen-induced disproportionation results in severe tritium trapping,thus impeding its practical application.Herein,an isostructural transition is successfully constructed with low hysterisis,ameliorated plateau flatness of pressure-composition isotherms and improved high-temperature durability for hydrogen trapping minimization.Specifically,the optimal Zr_(0.7)Hf_(0.15)Nb_(0.15)Co_(0.6)Cu_(0.15)Ni_(0.25) alloy adopts Hf-Nb and Cu-Ni as Zr and Co side doping elements,exhibiting substantial thermodynamic destabilization with nearly 90℃ reduction of delivery temperature,and significant kinetic promotion with a threefold lower energy barrier.More importantly,both hydrogen utilization and cycling retention of optimal alloy are increased by about twenty times compared with pristine alloy after 100 cycles at 500℃.Minimized disproportionation driving force from both isostructural transition and suppressed 8e hydrogen occupation realizes full potential of optimal alloy.This work demonstrates the effectiveness of combining isostructural transformation and high-temperature durability improvement to enhance the hydrogen utilization of ZrCo-based alloys and other hydrogen storage materials.展开更多
Surface recrystallization(RX) is a typical grain defect observed in directionally solidified(DS) Ni-based superalloys. Most studies have focused on the RX behavior and its impact on the mechanical properties of single...Surface recrystallization(RX) is a typical grain defect observed in directionally solidified(DS) Ni-based superalloys. Most studies have focused on the RX behavior and its impact on the mechanical properties of single-crystal(SC) superalloys, with limited research on its influence on the high-temperature mechanical properties of DS superalloys. This study systematically investigated the effect of RX on the high-temperature tensile properties of a DS DZ409 superalloy. The results show that at 650℃, the yield strength decreases almost linearly with an increase in RX fraction. A significant reduction in elongation is observed as the RX fraction increases from 0% to 4.9%. However, beyond this point, further increase in RX fraction leads to minimal changes in elongation. At 950℃, both yield strength and elongation decrease as the RX fraction increases from 0% to 4.9%. At 650℃, fractures in the RX DS superalloys exhibit a mixed mode of transgranular and intergranular cleavage fracture, while at 950℃, it features a combination of ductile and intergranular dimple fractures. The failure mechanism of the RX DS superalloy is associated with the introduction of transverse grain boundaries(GBs) during RX. In the early stages of tensile testing at intermediate and high temperatures, cracks can easily initiate at these GBs. Subsequently, the cracks propagate along the GBs into the DS matrix, ultimately leading to failure of the DS superalloy.展开更多
By using fatigue crack propagation testing and microstructural characterization,the crack fracture and propagation mechanisms of K4169 superalloy under various loads were investigated.The results demonstrate that the ...By using fatigue crack propagation testing and microstructural characterization,the crack fracture and propagation mechanisms of K4169 superalloy under various loads were investigated.The results demonstrate that the grain sizes of K4169 superalloy significantly increase,and the precipitation of the needle-likeδphase and the Laves phase is observed.Voids and microcracks form at location of Laves phase enrichment,creating conditions for crack propagation.By the a−N(a is the crack length,and N is the number of cycles)relationship curve,the change in the fatigue crack growth rate with the increasing number of cycles progresses through three separate stages.The fracture process of K4169 superalloy under low-stress cyclic loading(3 kN)exhibits the ductile fracture.Subsequently,the fracture process starts to change from the ductile fracture to the brittle fracture as the stress increases to 4.5 kN.In the microstructures of fractures in both stress states,intergranular propagation is the mechanism responsible for crack propagation.Moreover,the Laves phase exists near the fracture crack,which is in line with the post-service structural phenomenon.展开更多
The development of flexible supercapacitors(FSCs) capable of operating at high temperatures is crucial for expanding the application areas and operating conditions of supercapacitors. Gel polymer electrolytes and elec...The development of flexible supercapacitors(FSCs) capable of operating at high temperatures is crucial for expanding the application areas and operating conditions of supercapacitors. Gel polymer electrolytes and electrode materials stand as two key components that significantly impact the efficacy of hightemperature-tolerant FSCs(HT-FSCs). They should not only exhibit high electrochemical performance and excellent flexibility, but also withstand intense thermal stress. Considerable efforts have been devoted to enhancing their thermal stability while maintaining high electrochemical and mechanical performance. In this review, the fundamentals of HT-FSCs are outlined. A comprehensive overview of state-of-the-art progress and achievements in HT-FSCs, with a focus on thermally stable gel polymer electrolytes and electrode materials is provided. Finally, challenges and future perspectives regarding HT-FSCs are discussed, alongside strategies for elevating operational temperatures and performance.This review offers both theoretical foundations and practical guidelines for designing and manufacturing HT-FSCs, further promoting their widespread adoption across diverse fields.展开更多
The research demonstrated that laser powder bed fusion(LPBF)coupled with controlled annealing at 1200°C,could significantly increase the proportion of coincidence site lattice(CSL)grain boundary,thereby achieving...The research demonstrated that laser powder bed fusion(LPBF)coupled with controlled annealing at 1200°C,could significantly increase the proportion of coincidence site lattice(CSL)grain boundary,thereby achieving an outstanding synergy of enhanced strength and exceptional ductility.The plastic deformation behavior,strain hardening behavior,and fracture behavior of LPBF 316L steel annealing at 1200℃for 20 h were studied through quasi-in-situ tensile process.It was found that LPBF 316L steel formed a certain proportion of deformation twins during the tensile process,and the formation of twins changed the crystal orientation,thus promoting further slip and crystal deformation.The synergistic effect of slip and twin promoted higher plasticity.LPBF process coupled with controlled annealing at 1200°C for 20 h leads to a ultimate tensile strength of 613 MPa and total elongation of 73.8%.展开更多
Traditionally,the construction of stable interphases relies on solvent structures dominated by aggregated anionic structures(AGG/AGG+).Nonetheless,we find that the construction of stable interphases in hightemperature...Traditionally,the construction of stable interphases relies on solvent structures dominated by aggregated anionic structures(AGG/AGG+).Nonetheless,we find that the construction of stable interphases in hightemperature environments is based on contact ion pairs(CIPs)dominated solvation structure here.In detail,in the long-chain phosphate ester-based electrolyte,the spatial site-blocking effect enables the strong solvation co-solvent ether(diethylene glycol dimethyl ether,G2)to exhibit strong ion-dipole interactions,further multicomponent competitive coordination maintaining the CIP,balancing electrode kinetics,and optimizing the high-temperature interphases.High-temperature in-situ Raman spectroscopy monitors the changes in the stable solvent structure during charge/discharge processes for the first time,and time of flight secondary ion mass spectrometry(TOF-SIMS)reveals the stable solid electrolyte interphase(SEI)with full-depth enrichment of the inorganic component.Benefiting from the high-temperature interfacial chemistry-dependent solvent structure,the advanced electrolyte enables stable cycling of 1.6 Ah 18650 batterie at 100-125℃and discharging with high current pulses(~1.83 A)at 150℃,which has rarely been reported so far.In addition,pin-pricking of 18650 batteries at100%state of charge(SoC)without fire or smoke and the moderate thermal runaway temperature(187℃)tested via the accelerating rate calorimetry(ARC)demonstrate the excellent safety of the optimized electrolyte.展开更多
基金supported by the National basic scientific research projects(JCKY2021204A004)the National Ministries and Commissions Projects(2019-112hbz)the National Natural Science Foundation of China(No.52271113).
文摘Ti750s titanium alloy,a novel high-temperature titanium alloy designed for short-term service at elevated temperatures(700–750℃),has previously lacked comprehensive understanding of its hot processing behavior.In this study,the high-temperature deformation behavior and microstructural evolution of the Ti750s alloy were systematically investigated through thermal simulation compression tests conducted at temperatures ranging from 900 to 1070℃and strain rates between 0.1 and 10 s⁻1.A hot processing map was constructed using the dynamic material model to optimize the hot processing parameters.The results indicated that the optimal processing window was between 1040 and 1070℃with a strain rate of 0.1 s⁻1.Processing within the instability region resulted in localized plastic deformation,manifesting as pronounced shear bands and a highly heterogeneous strain distribution;this region should be avoided during hot deformation.Within theα+βphase safety zone characterized by low power dissipation rates between 0.32 and 0.4,the primary deformation mechanism in this region was dynamic recovery(DRV),where the lamellarαgrains underwent deformation and rotation.Conversely,in theα+βphase safety zone with high-power dissipation rates between 0.45 and 0.52,dynamic spheroidization of theαphase and dynamic recrystallization(DRX)of theβphase occurred concurrently.In theβphase safety zone with low power dissipation rates between 0.32 and 0.51,the primary deformation mechanism consisted of DRV ofβgrains,accompanied by limited DRX.However,in theβphase safety zone with high-power dissipation rates exceeding 0.56,both DRV and DRX ofβgrains took place,resulted in a significant increase in the size and number of recrystallized grains compared to those observed under low power dissipation conditions.
基金the joint financial support from the National Natural Science Foundation of China and Baowu Group Co.,Ltd.(Grant No.U1660205)the Fundamental Research Funds for the Central Universities(Grant No.N2007001).
文摘The high melting point element W and the rare earth element Ce were added to 18Cr-Mo(444-type)ferritic stainless steel to improve its high-temperature oxidation resistance in exhaust gas.A simulated exhaust gas was filled in the simultaneous thermal analyzer to simulate the service environment,and the oxidation behavior in high-temperature exhaust gas environment of 444-type ferritic stainless steel alloyed with W and Ce was investigated.The oxide structure and composition formed in this process were analyzed and characterized by scanning electron microscopy/energy-dispersive spectroscopy and electron probe analysis,and the mechanism of W and Ce in the oxidation process was revealed.The results show that 18Cr-Mo ferritic stainless steel containing W and Ce has better oxidation resistance in high-temperature exhaust gas.The element W can promote the precipitation of Laves phase at the matrix/interface,inhibit the interface diffusion of oxidizing elements and prevent the inward growth of the oxide film.The element Ce can suppress the volume of SiO_(2)at the oxide film/interface,reducing the breakaway oxidation caused by cracking of the oxide film.The CeO_(2)provides nucleation sites for oxide particles,promoting the healing of cracks and voids within the oxide film.
文摘This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standard system was established for comprehensive quality evaluation of HTD.There were obvious changes in the physicochemical properties,enzyme activities,and volatile flavor components at different storage periods,which affected the sensory evaluation of HTD to a certain extent.The results of high-throughput sequencing revealed significant microbial diversity,and showed that the bacterial community changed significantly more than did the fungal community.During the storage process,the dominant bacterial genera were Kroppenstedtia and Thermoascus.The correlation between dominant microorganisms and quality indicators highlighted their role in HTD quality.Lactococcus,Candida,Pichia,Paecilomyces,and protease activity played a crucial role in the formation of isovaleraldehyde.Acidic protease activity had the greatest impact on the microbial community.Moisture promoted isobutyric acid generation.Furthermore,the comprehensive quality evaluation standard system was established by the entropy weight method combined with multi-factor fuzzy mathematics.Consequently,this study provides innovative insights for comprehensive quality evaluation of HTD during storage and establishes a groundwork for scientific and rational storage of HTD and quality control of sauce-flavor Baijiu.
基金supported by the National Natural Science Foundation of China(Grant No.U21B2062)supported by the Key Laboratory for Carbonate Reservoirs of China National Petroleum Corporation。
文摘Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.
基金supported by the National Key R&D Program of China(No.2022YFB3707700)National Natural Science Foundation of China(No.52302121)+3 种基金Shanghai Sailing Program(No.23YF1454700)Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664)Shanghai Science and Technology Innovation Action Plan(No.21511104800).
文摘The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.
基金National Natural Science Foundation of China(52376076)Open Fund of Material Corrosion and Protection Key Laboratory of Sichuan Province(2023CL13)Laiwu Vocational and Technical College Teachers Research Fund(2023jsky05)。
文摘Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose hardness is 65 HRC and flexural strength is 1450 MPa.The high-temperature oxidation mechanism of TiC-based cermets was investigated through an X-ray diffractometer and scanning electron microscope.The added elements Ni and Cr along with their solid solutions not only bond with the hard phase TiC to ensure the physical performance of the cermet,but also impede the internal diffusion during oxidation by forming a dense composite oxide layer,thereby enhancing the oxidation resistance.The TiC-NiCr cermet exhibits a dense protective oxide layer at 900℃ and can endure continuous oxidation for approximately 1000 h.A methodology for fabricating TiC-NiCr metal matrix composites is proposed,and their oxidation resistance is evaluated,providing a theoretical and practical basis for simultaneously enhancing the mechanical properties and oxidation resistance and reducing production costs.
基金National Natural Science Foundation of China(12404230,52061027)Science and Technology Program Project of Gansu Province(22YF7GA155)+1 种基金Lanzhou Youth Science and Technology Talent Innovation Project(2023-QN-91)Zhejiang Provincial Natural Science Foundation of China(LY23E010002)。
文摘(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co content on microstructure and mechanical properties were investigated.The results indicate that the grain size of the alloy decreases with increasing the Co content.In the as-cast state,the alloy consists primarily of the B19′phase,with a trace of B2 phase.The fracture morphology is predominantly composed of the B19′phase,whereas the B2 phase is nearly absent.Increasing the Co content or reducing the sample dimensions(d)markedly enhance the compressive strength and ductility of the alloy.When d=2 mm,the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy demonstrates the optimal mechanical properties,achieving a compressive strength of 2142.39±1.8 MPa and a plasticity of 17.31±0.3%.The compressive cyclic test shows that with increasing the compressive strain,the residual strain of the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy increases while the recovery ability declines.The superelastic recovery capability of the alloy is continuously enhanced.The superelastic recovery rate increases from 1.36%to 2.12%,the residual strain rate rises from 1.79%to 5.52%,the elastic recovery rate ascends from 3.86%to 7.36%,while the total recovery rate declines from 74.48%to 63.20%.
基金National Natural Science Foundation of China(Grant No.51971215).
文摘In this study,the oxidation behavior of Ti42Al5Mn,Ti42Al5Mn0.5 W,Ti42Al5Mn0.5W0.1B,and Ti42Al5Mn0.8 W was investigated at 800℃.Due to the inability to form a dense protective Al2O_(3) layer,Ti42Al5Mn suffered severe spallation during oxidation at 800℃and the mass gain was significant.The intermediate layer between the scale and the substrate was first composed of Laves/Z phase but changed toα2/Z phase with prolonged oxidation.The intermediate layer with high Ti/Al ratio favors the forma-tion of a thick Al2O_(3)+TiO_(2) mixed layer in the oxide scale which is prone to initiate cracks and cause the spalling of oxides.The doping of W in TiO_(2) effectively inhibited its generation and promoted the for-mation of a dense Al2O_(3) layer,resulting in a significant improvement in the oxidation resistance of the alloy.Compared to Ti42Al5Mn alloy,Ti42Al5Mn0.8 W showed no spallation after 300 h cyclic oxidation and the kinetic curve changed from liner law to parabolic law.The intermediate layer of Ti42Al5Mn0.8 W alloy was composed of a single Laves phase and remained unchanged even after 1000 h oxidation at 800℃,offering a favorable basis for the generation of a stable protective oxide layer in the alloy.The addi-tion of 0.1 at.%B to Ti42Al5Mn0.5 W alloy refined its microstructure and further improved its spallation resistance to a level close to that of Ti42Al5Mn0.8 W alloy.
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
基金supported by the National Natural Science Foundation of China(Nos.52174175 and 52274078)the Program for the Scientific and Technological Innovation Team in Universities of Henan Province(No.23IRTSTHN005)。
文摘The tensile strength of rocks under real-time high-temperatures is essential for enhanced geothermal system development.However,the complex occurrence and deep burial of hot dry rocks limit the quantity and quality of standard samples for mechanical testing.This paper compared the tensile strengths obtained from Brazilian splitting tests on standard samples(with a diameter of 50 mm and a thickness of 25 mm)and micro-tensile samples(with a diameter of 50 mm and a thickness of 25 mm)of two types of granites.A power-law size effect model was established between the two sets of data,validating the reliability of the testing method.Then,miniature Brazilian splitting under real-time high-temperature,combined with X-ray diffraction(XRD)revealed temperature-dependent strength variations and microstructural damage mechanisms.The results show that:(1)The comparison error between the tensile strength obtained by the fitting model and that of the measured standard samples was less than 6%.(2)In real-time high-temperature conditions,tensile strength of granite exhibited non-monotonic behavior,increasing below 300°C before decreasing,with sharp declines at 400–500°C and 600–700°C.(3)Thermal damage stems from the differences in the high-temperature behavior of minerals,including dehydration,phase transformation,and differential expansion.
文摘With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components operating in high-temperature environments within the aerospace sector.However,typical high-temperature coatings currently face challenges in effectively integrating excellent oxidation resistance,wear resistance,and lubrication properties in high-temperature settings.Studies have demonstrated the significant potential of Transition Metal Dichalcogenides(TMDCs)as lubricant additives in high-temperature lubrication,attributable to their distinctive crystal structures.Thus,this review concentrates on the compositional design of individual MX_(2)-type(M=W,Mo,Nb,Ta;X=S,Se)TMDCs(molybdenum disulfide(MoS_(2)),tungsten disulfide(WS2),niobium diselenide(NbSe_(2)),molybdenum diselenide(MoSe_(2)),tungsten diselenide(WSe_(2)))and their composites,including inorganic oxygen-containing sulfides,and explores the utilization of TMDCs in self-lubricating coatings.Furthermore,conventional preparation methods(mechanical exfoliation,liquid-phase ultrasonic exfoliation,chemical vapour deposition)for synthesizing TMDCs are outlined.Finally,an analysis of the lubrication mechanism of MX_(2)-type TMDCs is provided,along with future directions for enhancing the high-temperature lubrication performance of composite coatings.
文摘Investigating highly effective electrocatalysts for high-temperature proton exchange membrane fuel cells(HT-PEMFC)requires the resistance to phosphate acid(PA)poisoning at cathodic oxygen reduction reaction(ORR).Recent advancements in catalysts have focused on alleviating phosphoric anion adsorption on Pt-based catalysts with modified electronic structure or catalytic interface and developing Fe-N-C based catalysts with immunity of PA poisoning.Fe-N-C-based catalysts have emerged as promising alternatives to Pt-based catalysts,offering significant potential to overcome the characteristic adsorption of phosphate anion on Pt.An overview of these developments provides insights into catalytic mechanisms and facilitates the design of more efficient catalysts.This review begins with an exploration of basic poisoning principles,followed by a critical summary of characterization techniques employed to identified the underlying mechanism of poisoning effect.Attention is then directed to endeavors aimed at enhancing the HT-PEMFC performance by well-designed catalysts.Finally,the opportunities and challenges in developing the anti-PA poisoning strategy and practical HT-PEMFC is discussed.Through these discussions,a comprehensive understanding of PA-poisoning bottlenecks and inspire future research directions is aim to provided.
基金supported by the National Natural Science Foundation of China(Nos.51831004 and 52171006).
文摘The Al-Cu alloy is a historical model alloy system in the physical metallurgy of engineering aluminum al-loys.Nevertheless,a few fundamental phenomena of phase transformation occurring in this simple alloy are still not adequately understood.Among all,for instance,the formation mechanisms of its key harden-ingθ'-phase remain mysterious.There is strong evidence thatθ'-precipitates can form from a different high-temperature precipitation pathway,while their formation mechanism via the conventional pathway well-known since 1938 remains to be clarified.Using state-of-the-art electron microscopy,here we report a secondary high-temperature precipitation pathway ofθ'-precipitates.It is demonstrated that led by a secondary high-temperature precursor,namedθ'_(S-HTP),very fineθ'-precipitates can form in the unde-formed bulk Al-Cu alloys at elevated temperatures(≥250℃).Interestingly is that with Sc-microalloying the surviving rate of meta-stableθ'_(S-HTP) precipitates increases drastically and the formedθ'-precipitates become much finer,significantly enhancing the alloys’strength and thermal stability.It is also revealed that aθ'_(S-HTP) precipitate can genetically evolve into aθ'-precipitate without having to change its mor-phology and orientation.Our study provides new insights into understanding the industry bulk alloys’microstructures and properties.
文摘Considering the fracture problem of the silica-based ceramic core in the integrated casting of hollow turbine blades during directional solidification,the influence of various whiskers,including silicon carbide whiskers,silicon nitride whiskers,and mullite whiskers,on the high-temperature strength of the silica-based ceramic core was investigated.Additionally,the formation of microstructure morphology and phase structure was analyzed.Research results show that silicon carbide whiskers can reduce the microcracks caused by the shrinkage of cristobalite.During the sintering process,some of the silicon carbide whiskers oxidize and react with aluminum powder to form mullite,which can improve the high-temperature strength of the ceramic cores.When the content of silicon carbide whiskers is 3wt.%,the high-temperature bending strength of the cores reaches the maximum value of 21 MPa.Silicon nitride whiskers decompose in a high-temperature environment and react with aluminum powder in the matrix material to form mullite whiskers.When the content of silicon nitride whiskers is 5wt.%,the high-temperature bending strength of the cores reaches 20 MPa.By adding mullite whiskers,a structure of cristobalite wrapped mullite whiskers can be formed to achieve toughening.When the content of mullite whiskers is 4wt.%,the high-temperature bending strength can reach 17.2 MPa.By comparing the performance of silicon carbide whiskers,silicon nitride whiskers,and mullite whiskers,along with conducting slurry viscosity tests and casting experiments,it is determined that a ceramic slurry containing 4wt.%mullite whiskers is the most suitable for making the cores used in the integrated casting of hollow turbine blades.
基金supports from the National Key Research and Development Program of China(2022YFE03170002)the National Natural Science Foundation of China(52071286 and U2030208).
文摘The launch of International Thermonuclear Experimental Reactor project paves the way to wide adoption of DT fusion energy as future energy source.Efficient fuel cycle to minimize strategic tritium inventory proves crucial for commercially viable fusion technologies.ZrCo alloy is considered as a promising candidate for fast isotope handling.However,cycling degradation caused by hydrogen-induced disproportionation results in severe tritium trapping,thus impeding its practical application.Herein,an isostructural transition is successfully constructed with low hysterisis,ameliorated plateau flatness of pressure-composition isotherms and improved high-temperature durability for hydrogen trapping minimization.Specifically,the optimal Zr_(0.7)Hf_(0.15)Nb_(0.15)Co_(0.6)Cu_(0.15)Ni_(0.25) alloy adopts Hf-Nb and Cu-Ni as Zr and Co side doping elements,exhibiting substantial thermodynamic destabilization with nearly 90℃ reduction of delivery temperature,and significant kinetic promotion with a threefold lower energy barrier.More importantly,both hydrogen utilization and cycling retention of optimal alloy are increased by about twenty times compared with pristine alloy after 100 cycles at 500℃.Minimized disproportionation driving force from both isostructural transition and suppressed 8e hydrogen occupation realizes full potential of optimal alloy.This work demonstrates the effectiveness of combining isostructural transformation and high-temperature durability improvement to enhance the hydrogen utilization of ZrCo-based alloys and other hydrogen storage materials.
基金supported by the National Science and Technology Major Project(No.HT-J2019-VI-0020-0136)the National Youth Talent Support Program,and the Fundamental Research Funds for the Central Universities(No.xtr072024004).
文摘Surface recrystallization(RX) is a typical grain defect observed in directionally solidified(DS) Ni-based superalloys. Most studies have focused on the RX behavior and its impact on the mechanical properties of single-crystal(SC) superalloys, with limited research on its influence on the high-temperature mechanical properties of DS superalloys. This study systematically investigated the effect of RX on the high-temperature tensile properties of a DS DZ409 superalloy. The results show that at 650℃, the yield strength decreases almost linearly with an increase in RX fraction. A significant reduction in elongation is observed as the RX fraction increases from 0% to 4.9%. However, beyond this point, further increase in RX fraction leads to minimal changes in elongation. At 950℃, both yield strength and elongation decrease as the RX fraction increases from 0% to 4.9%. At 650℃, fractures in the RX DS superalloys exhibit a mixed mode of transgranular and intergranular cleavage fracture, while at 950℃, it features a combination of ductile and intergranular dimple fractures. The failure mechanism of the RX DS superalloy is associated with the introduction of transverse grain boundaries(GBs) during RX. In the early stages of tensile testing at intermediate and high temperatures, cracks can easily initiate at these GBs. Subsequently, the cracks propagate along the GBs into the DS matrix, ultimately leading to failure of the DS superalloy.
基金National Natural Science Foundation of China (No. 51975200)Hunan Provincial Innovation Foundation for Postgraduate,China (No. QL20220201)。
文摘By using fatigue crack propagation testing and microstructural characterization,the crack fracture and propagation mechanisms of K4169 superalloy under various loads were investigated.The results demonstrate that the grain sizes of K4169 superalloy significantly increase,and the precipitation of the needle-likeδphase and the Laves phase is observed.Voids and microcracks form at location of Laves phase enrichment,creating conditions for crack propagation.By the a−N(a is the crack length,and N is the number of cycles)relationship curve,the change in the fatigue crack growth rate with the increasing number of cycles progresses through three separate stages.The fracture process of K4169 superalloy under low-stress cyclic loading(3 kN)exhibits the ductile fracture.Subsequently,the fracture process starts to change from the ductile fracture to the brittle fracture as the stress increases to 4.5 kN.In the microstructures of fractures in both stress states,intergranular propagation is the mechanism responsible for crack propagation.Moreover,the Laves phase exists near the fracture crack,which is in line with the post-service structural phenomenon.
基金Fundamental Research Funds for the Central Universities of China(Grant No. SWU-KT22030)Scientific and Technological Research Program of Chongqing Municipal Education Commission of China (No.KJQN202300205)financial support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under the project of 457444676。
文摘The development of flexible supercapacitors(FSCs) capable of operating at high temperatures is crucial for expanding the application areas and operating conditions of supercapacitors. Gel polymer electrolytes and electrode materials stand as two key components that significantly impact the efficacy of hightemperature-tolerant FSCs(HT-FSCs). They should not only exhibit high electrochemical performance and excellent flexibility, but also withstand intense thermal stress. Considerable efforts have been devoted to enhancing their thermal stability while maintaining high electrochemical and mechanical performance. In this review, the fundamentals of HT-FSCs are outlined. A comprehensive overview of state-of-the-art progress and achievements in HT-FSCs, with a focus on thermally stable gel polymer electrolytes and electrode materials is provided. Finally, challenges and future perspectives regarding HT-FSCs are discussed, alongside strategies for elevating operational temperatures and performance.This review offers both theoretical foundations and practical guidelines for designing and manufacturing HT-FSCs, further promoting their widespread adoption across diverse fields.
基金Project(52474418)supported by the National Natural Science Foundation of ChinaProject(YDZJSX2022A012)supported by the Central Guiding Local Science and Technology Development Foundation,China。
文摘The research demonstrated that laser powder bed fusion(LPBF)coupled with controlled annealing at 1200°C,could significantly increase the proportion of coincidence site lattice(CSL)grain boundary,thereby achieving an outstanding synergy of enhanced strength and exceptional ductility.The plastic deformation behavior,strain hardening behavior,and fracture behavior of LPBF 316L steel annealing at 1200℃for 20 h were studied through quasi-in-situ tensile process.It was found that LPBF 316L steel formed a certain proportion of deformation twins during the tensile process,and the formation of twins changed the crystal orientation,thus promoting further slip and crystal deformation.The synergistic effect of slip and twin promoted higher plasticity.LPBF process coupled with controlled annealing at 1200°C for 20 h leads to a ultimate tensile strength of 613 MPa and total elongation of 73.8%.
基金supported by the National Natural Science Foundation of China(grant no.52072322,52202235)the Department of Science and Technology of Sichuan Province(CN)(grant no.23GJHZ0147)the Research and Innovation Fund for Graduate Students of Southwest Petroleum University(No.:2022KYCX111)。
文摘Traditionally,the construction of stable interphases relies on solvent structures dominated by aggregated anionic structures(AGG/AGG+).Nonetheless,we find that the construction of stable interphases in hightemperature environments is based on contact ion pairs(CIPs)dominated solvation structure here.In detail,in the long-chain phosphate ester-based electrolyte,the spatial site-blocking effect enables the strong solvation co-solvent ether(diethylene glycol dimethyl ether,G2)to exhibit strong ion-dipole interactions,further multicomponent competitive coordination maintaining the CIP,balancing electrode kinetics,and optimizing the high-temperature interphases.High-temperature in-situ Raman spectroscopy monitors the changes in the stable solvent structure during charge/discharge processes for the first time,and time of flight secondary ion mass spectrometry(TOF-SIMS)reveals the stable solid electrolyte interphase(SEI)with full-depth enrichment of the inorganic component.Benefiting from the high-temperature interfacial chemistry-dependent solvent structure,the advanced electrolyte enables stable cycling of 1.6 Ah 18650 batterie at 100-125℃and discharging with high current pulses(~1.83 A)at 150℃,which has rarely been reported so far.In addition,pin-pricking of 18650 batteries at100%state of charge(SoC)without fire or smoke and the moderate thermal runaway temperature(187℃)tested via the accelerating rate calorimetry(ARC)demonstrate the excellent safety of the optimized electrolyte.
