In this work, a simulated aircraft fuel tank inerting system has been successfully estab- lished based on a model tank. Experiments were conducted to investigate the influences of different operating parameters on the...In this work, a simulated aircraft fuel tank inerting system has been successfully estab- lished based on a model tank. Experiments were conducted to investigate the influences of different operating parameters on the inerting effectiveness of the system, including flow rate of the inert gas （nitrogen-enriched air）, inert gas concentration, fuel load of the tank and different inerting approaches. The experimental results show that under the same operating conditions, the time span of a complete inerting process decreased as the flow rate of inert gas was increased; the time span using the inert gas with 5% oxygen concentration was much longer than that using pure nitrogen; when the fuel tank was inerted using the ullage washing approach, the time span increased as the fuel load was decreased; the ullage washing approach showed the best inerting performance when the time span of a complete inerting process was the evaluation criterion, but when the decrease of dissolved oxygen concentration in the fuel was also considered to characterize the inerting effective- ness, the approach of ullage washing and fuel scrubbing at the same time was the most effective.展开更多
The properties of aviation fuel have a great influence on the performance of oxygenconsuming inerting systems. Based on the establishment of the catalytic inerting process, the flow relationship of each gas component ...The properties of aviation fuel have a great influence on the performance of oxygenconsuming inerting systems. Based on the establishment of the catalytic inerting process, the flow relationship of each gas component flowing through the catalytic reactor was derived. The mathematical model of the gas concentration in the gas phase of the fuel tank was established based on the mass conservation equation, and the fuel tank model was verified by performing experiments.The results showed that the fuel type exerts a considerably higher influence on the performance of the oxygen-consuming inerting system compared to the corresponding influence on the hollow fiber membrane system, and the relative magnitude of the inerting rates of the four fuel types is RP5 > RP3 > RP6 > JP8. In addition, a higher catalytic efficiency or fuel load rate corresponds to a higher rate of decrease of the oxygen concentration in the gas phase, and the inerting time is inversely proportional to the suction flow rate of the fan. When different fuels are used, the amount of cooling gas and water released from the inerting system are different. Therefore, the influence of fuel type on the system performance should be extensively considered in the future.展开更多
Fuel tank inerting technologies are able to reduce the fire risk by injection of inert gas into the ullage or fuel, the former called ullage washing and the latter fuel scrubbing. The Green On-Board Inert Gas Generati...Fuel tank inerting technologies are able to reduce the fire risk by injection of inert gas into the ullage or fuel, the former called ullage washing and the latter fuel scrubbing. The Green On-Board Inert Gas Generation System（GOBIGGS） is a novel technology based on flameless catalytic combustion, and owning to its simple structure and high inerting efficiency, it has received a lot of attentions. The inert gas in the GOBIGGS is mainly comprised of CO2, N2, and O2（hereinafter, Mixed Inert Gas（MIG））, while that in the On-Board Inert Gas Generation System（OBIGGS）, which is one of the most widely used fuel tank inerting technologies, is NitrogenEnriched Air（NEA）. The solubility of CO2 is nearly 20 times higher than that of N2 in jet fuels,so the inerting capability and performance are definitely disparate if the inert gas is selected as NEA or MIG. An inerting test bench was constructed to compare the inerting capabilities between NEA and MIG. Experimental results reveal that, if ullage washing is adopted, the variations of oxygen concentrations on the ullage and in the fuel are nearly identical no matter the inert gas is NEA or MIG. However, the ullage and dissolved oxygen concentrations of MIG scrubbing are always higher than those of NEA scrubbing.展开更多
1.Introduction Artificial intelligence(AI)is a rapidly growing field of technol-ogy,which“will enliven inert objects,much as electricity did more than a century ago.Everything that we formerly electrified will now co...1.Introduction Artificial intelligence(AI)is a rapidly growing field of technol-ogy,which“will enliven inert objects,much as electricity did more than a century ago.Everything that we formerly electrified will now cognitize”[1].AI advances are constantly pushing the frontier of what machines can do.Increased attention is being placed on AI research,as well as its development and deployment by commer-cial investors,defense strategists,and policy makers[2].展开更多
The thermal stresses relaxation of Ni/NiFe2O4 system functionally graded cermet inert anode for aluminum electrolysis was optimally designed. The transient thermal stresses of the inert anode under complex boundary co...The thermal stresses relaxation of Ni/NiFe2O4 system functionally graded cermet inert anode for aluminum electrolysis was optimally designed. The transient thermal stresses of the inert anode under complex boundary condition during high-temp （955℃） electrolysis were calculated using the finite-element software ANSYS, the influence of different parameters on the distribution of the thermal stresses were analyzed. The results showed that, during the process of thermal shock, the thermal hoop tensile stress on the surface of the anode is very large, which is possibly the major cause of anode crack; when the radius of the anode is between 0.05-0.15m, a range that can be realized by recent manufacturing technology, the optimum composition distribution exponent p is 0.25; The hoop tensile stresses reduce with the decrease of anode scale and also decrease with the decrease of the convection coefficient between the electrolyte and the anode.展开更多
Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to...Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to enhance the dynamic performance. The X-structure is used as a mechanism to realize the nonlinear stiffness characteristic of the NES, which can realize the flexibility, adjustability, high efficiency, and easy operation of nonlinear stiffness, and is convenient to apply in the vehicle suspension, and the inerter is applied to replacing the mass of the NES based on the mass amplification characteristic. The dynamic model of the half-vehicle system coupled with the IX-NES is established with the Lagrange theory, and the harmonic balance method(HBM) and the pseudo-arc-length method(PALM) are used to obtain the dynamic response under road harmonic excitation. The corresponding dynamic performance under road harmonic and random excitation is evaluated by six performance indices, and compared with that of the original half-vehicle system to show the benefits of the IX-NES. Furthermore, the structural parameters of the IX-NES are optimized with the genetic algorithm. The results show that for road harmonic and random excitation, using the IX-NES can greatly reduce the resonance peaks and root mean square(RMS) values of the front and rear suspension deflections and the front and rear dynamic tire loads, while the resonance peaks and RMS values of the vehicle body vertical and pitching accelerations are slightly larger.When the structural parameters of the IX-NES are optimized, the vehicle body vertical and pitching accelerations of the half-vehicle system could reduce by 2.41% and 1.16%,respectively, and the other dynamic performance indices are within the reasonable ranges.Thus, the IX-NES combines the advantages of the inerter, X-structure, and NES, which improves the dynamic performance of the half-vehicle system and provides an effective option for vibration attenuation in the vehicle engineering.展开更多
The dynamic vibration absorber with inerter and grounded stiffness(IGDVA)is used to control a two-scale system subject to a weak periodic perturbation.The vibration suppression effect is remarkable.The amplitude of th...The dynamic vibration absorber with inerter and grounded stiffness(IGDVA)is used to control a two-scale system subject to a weak periodic perturbation.The vibration suppression effect is remarkable.The amplitude of the main system coupled with absorber is significantly reduced,and the high frequency vibration completely disappears.First,through the slow-fast analysis and stability theory,it is found that the stability of the autonomous system exerts a notable regulating effect on the vibration response of the non-autonomous system.After adding the dynamic vibrator absorber,the center in the autonomous system changes to an asymptotically stable focus,consequently suppressing the vibration in the non-autonomous system.Further research reveals that the parameters of the absorber affect the real parts of the eigenvalues of the autonomous system,thereby regulating the stability of the system.Transitioning from a qualitative standpoint to a quantitative approach,a comparison of the solutions before and after the introduction of the dynamic absorber reveals that,when the grounded stiffness ratio and the mass ratio of the dynamic absorber are not equal,the high-frequency part in the analytical solution disappears.As a result,this leads to a reduction in the amplitude of the trajectory,achieving a vibration reduction effect.展开更多
When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural dur...When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural durability and ensure the users′comfort level.This study proposed an inerter-based optimal solution to suppress the vibrational forces and energy transmitted to the supporting ground by utilizing the great potential of the inerter.For the external force,which contains various frequency bands,the stochastic response and an energy balance analysis are conducted to evaluate the force transmissibility,structural displacement,and vibration power flow.Given the benefits of the inerter,a transmitted-force-based optimal design framework is proposed for inerter systems,of which the effectiveness is validated by numerical examples.The obtained results show that inerter systems are capable of providing significant reductions in the structural displacement and the force transmitted to the supporting ground.Particularly,the closed-form power equation indicated that a grounded inerter can suppress the force transmission and vibrational energy,thus leading to a less negative impact on the ground and environment.Revealing the working mechanism and optimal design strategy of the inerter can help solve the force-transmission control problem experienced by some practical structures.展开更多
In the presence of ethyl alcohol or emulsifier OP,molybdenum(Ⅵ) forms 1∶1∶1'water soluble colored coordination com- pound with both of 2-(2-thiazolylazo)-5-diethylaminophenol (abbreviation TAE) and hydroxylamin...In the presence of ethyl alcohol or emulsifier OP,molybdenum(Ⅵ) forms 1∶1∶1'water soluble colored coordination com- pound with both of 2-(2-thiazolylazo)-5-diethylaminophenol (abbreviation TAE) and hydroxylamine.This deep blue coordination compound is inert characteristically and remains stable in 1.7 mol/L sulfuric acid,2.4 mol/L hydrochloric or ni- tric acid.It will not be decomposed by masking agents even on boiled,while in that case,almost all the colored coordination com- pounds formed by other metal ions will be decomposed completely.This inert character of the coordination compound of molybdenum(Ⅵ) and its utilization in improving the analytical selectivity have been discussed.In the coexistence of various for- eign ions,especially in the presence of a great quantity of tungsten,which always interferes with the determination of molybdenum,the direct determination of molybdenum in the aqueous solution by applying this system has shown an acceptable sensitivity and reproducibility.From the results of determination in some synthetic and standard samples,it seems feasible to use this system in the determination of molybdenum in nonferrous alloys.展开更多
Inert gas-clustered systems (Xn, X = He, Ne, Ar and n = 2 - 20) were established in this study and their stability as a result of interparticulate interaction was examined. Ferric chloride and ferrous oxides were used...Inert gas-clustered systems (Xn, X = He, Ne, Ar and n = 2 - 20) were established in this study and their stability as a result of interparticulate interaction was examined. Ferric chloride and ferrous oxides were used as catalysts to promote reaction, and 5-nitro-1,2,4-triazol-3-one (NTO) was theoretically synthesized under an inert gas (X6)-clustered environment in this study. The raw material, urea, initially underwent chlorination using chlorine as the reagent, followed by amination, formylation and nitration. Reaction routes closely related to the experimental processes were successfully constructed, and the corresponding energy barriers were estimated for each elementary reaction. The findings revealed that the average errors in the B3LYP/6-31G(d, p)-calculated geometry and vibrational frequency of NTO in an Ne6 system relative to the observed values were 0.83% and 1.84%, respectively. The neon gas-clustered system achieved greater stabilization, which results from the difference in self-consistent field energy (ESCF), than the corresponding stabilization acquired in a helium- or argon-based system. Ferric chloride serves as a good catalyst to reduce the energy barrier of the chlorination reaction, and ferrous oxide is suitable for catalyzing the amination, formylation and nitration reactions, although nitric acid is the better agent for nitration. The catalytic Ne6-clustered reaction system is suggested to be a more feasible pathway for the synthesis of NTO.展开更多
Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-car...Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-carbon emissions and no chlorine gas evolution.The clean production stems from the choice of a molten NaCl-Na_(2)CO_(3) electrolyte to prevent chlorine gas evolution,an inert nickel-based anode to produce oxygen,and a liquid metal cathode to make the cathodic product sit at the bottom of the electrolytic cell.We achieve a current efficiency of>90%for the electrolytic production of liquid Na-Sn alloy.Later,Mg-Sn alloy is prepared using the obtained Na-Sn alloy to displace Mg from molten NaCl-MgCl_(2) with a displacement efficiency of>96%.Further,Na and Mg are separated from the electrolytic Na-Sn and displaced Mg-Sn alloys by vacuum distillation with a recovery rate of>92%and Sn can be reused.Using this electrolysisdisplacement-distillation(EDD)approach,we prepare Mg from seawater.The CO_(2)emission of the EDD approach is~20.6 kg CO_(2)per kg Mg,which is less than that of the Australian Magnesium(AM)electrolysis process(~25.0 kg CO_(2)per kg Mg)and less than half that of the Pidgeon process(~45.2 kg CO_(2)per kg Mg).展开更多
The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion...The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.展开更多
A dual-halide solid electrolyte,Li_(3)YCl_(3)Br_(3),was synthesized using a wet-chemistry route instead of the conventional mechanical ball-milling route.Li_(3)YCl_(3)Br_(3) exhibits an ion conductivity of 2.08 mS/cm ...A dual-halide solid electrolyte,Li_(3)YCl_(3)Br_(3),was synthesized using a wet-chemistry route instead of the conventional mechanical ball-milling route.Li_(3)YCl_(3)Br_(3) exhibits an ion conductivity of 2.08 mS/cm and an electro-chemical stability window of 3.8 V.Additionally,an all-solid-state lithium-ion battery using Li_(3)YCl_(3)Br_(3) and LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(NCM811)as the cathode material achieves a capacity retention of 93%after 200 cycles at 0.3C and maintains a specific capacity of 115 mA·h/g during 2C cycling.This exceptional performance is attributed to the high oxidative stability of Li_(3)YCl_(3)Br_(3) and the in-situ formation of Y_(2)O_(3) inert protective layer on the NCM811 surface under high voltage.Consequently,the study demonstrates the feasibility of a simple,cost-effective wet-chemistry route for synthesizing multi-component halides,highlighting its potential for large-scale production of halide solid electrolytes for practical applications.展开更多
The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial...The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial nonlinear energy sink(NES)is applied for the first time to achieve vibration suppression in beams under moving loads.Based on the Timoshenko beam theory,the nonlinear motion equations of a beam with an inertial NES are derived using the energy method and Lagrange equations.The Newmark-βmethod combined with the Heaviside step function is adopted to calculate the responses of the beam under moving loads of constant amplitude and harmonic excitation.The accuracy of the modelling derivation and solution methodology are validated through comparisons with results from other studies.The results demonstrate that the velocity and excitation frequency of the moving load significantly affect the response of the beam as well as the performance of the inertial NES.To enhance its effectiveness under various moving load conditions,parametric optimization is numerically performed.The optimized inertial NES can achieve good performance by efficiently reducing the maximum deflection of the beam.The findings of this study contribute to advancing the understanding and application of NESs in mitigating structural vibrations caused by moving loads.展开更多
Nonlinear characteristics have demonstrated significant advantages in mitigating vibrations across various engineering applications,particularly in effectively suppressing vibrations over a wide frequency range.This p...Nonlinear characteristics have demonstrated significant advantages in mitigating vibrations across various engineering applications,particularly in effectively suppressing vibrations over a wide frequency range.This paper introduces a novel nonlinear energy sink with a magnetic inerter(MINES).The MINES features a magnetic lead screw that incorporates a pair of helical permanent magnets.When the inner part undergoes linear motion,it is transformed into the rotation of the outer part at a predetermined conversion ratio.Subsequently,the MINES is incorporated into a system with a single degree of freedom,and the corresponding differential equations of motion are derived.The approximate analytical method and the numerical method are used to validate each other.This process clarifies the effectiveness of the MINES in reducing vibrations when subjected to harmonic excitation.The influence of the parameters of the MINES is analyzed.The findings demonstrate that the MINES offers significant benefits in terms of vibration suppression efficiency when the depths of the three barriers are equal.Furthermore,with the increase in excitation amplitude,the MINES enters the nonlinear range,leading to a reduction in system damping.This can effectively prevent the phenomenon of traditional damping stiffening under conditions of high amplitude excitation.Finally,the vibration reduction capability of this nonlinear energy sink was experimentally demonstrated,enhancing its applicability in vibration mitigation.展开更多
Tungsten inert gas(TIG)welding and laser beam welding(LBW)were employed on as-cast and as-forged Mg−8Li−3Al−2Zn−0.5Y(LAZ832-0.5Y)alloys to investigate their weldability.The microstructure and mechanical properties of ...Tungsten inert gas(TIG)welding and laser beam welding(LBW)were employed on as-cast and as-forged Mg−8Li−3Al−2Zn−0.5Y(LAZ832-0.5Y)alloys to investigate their weldability.The microstructure and mechanical properties of solid solution treated samples were investigated for the purpose of further strength improvement,which were treated at 350℃ for 4 h.The ultimate tensile strength(UTS)and yield strength(YS)of the optimal TIG as-cast alloy welding joint were 159 and 122 MPa,which were obtained under the welding current of 80 A,and were lower than the UTS(184 MPa)and YS(146 MPa)of the optimal LBW as-forged welding joint under the power of 2.1 kW/2.0 kW double-side welding.After the solid solution treatment,on the one hand,the growth ofα-Mg grains in the fusion zone(FZ),heat affected zone(HAZ)and base metal(BM)of both the TIG and LBW welding joints was insignificant.On the other hand,the larger Al_(2)Y phases were still present,while the much smaller white AlLi particles were dissolved into the matrix,leading to the solid solution strengthening of the welding joints.As a result,the UTS and YS of the TIG welding joint respectively increased to 216 and 188 MPa after solid solution treatment,and those of the LBW welding joint only increased to 211 and 160 MPa,respectively.展开更多
CaO-based heat carriers have shown great prospects for thermochemical energy storage in concentrated solar power systems due to the features such as rich reserves,environmental safety,high energy storage densities and...CaO-based heat carriers have shown great prospects for thermochemical energy storage in concentrated solar power systems due to the features such as rich reserves,environmental safety,high energy storage densities and high operation temperatures.However,the density decay because of sintering and poor direct solar absorption of white CaO based heat carriers are the two main obstacles lying on the way to the realistic applications.This work introduced dark Mn-based inert support into calcium heat carriers,attempting to solve the above problems simultaneously.As an inert support,the finely dispersed Ca_(2)MnO_(4) functioned as the metal framework to resist CaCO_(3)/CaO sintering.Consequently,the cyclic stability of CaO-based heat carriers,resulting in the high energy storage densities of~2000 kJ/kg even over 20 cycles.As a dark material,Ca_(2)MnO_(4) successfully darkened CaO-based heat carriers,thereby greatly enhanced the direct solar absorption.In addition,the granulation of CaO-based heat carriers was also studied.The pellets showed satisfactory attrition resistance with only 9.85 wt% mass loss over 3200 cycles.In general,good physicochemical performance of Mn-doped CaO-based heat carrier endows it with great prospects for solar energy storage.展开更多
Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operati...Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operational costs,particularly for hydrocarbons with high boiling points or strong host-vip interactions[2].This is the same case in the newly-developed macrocyclebased crystalline adsorbents,namely nonporous adaptive crystals(NACs).To address these challenges,a recent study published in Angewandte Chemie International Edition by Jie,Ma,and co-workers reported an innovative molecular-"squeeze"triggered desorption mechanism in NACs[3-5].Specifically,ethyl acetate(EA)triggers vip desorption without penetrating the crystal pores or voids.Instead,EA molecules interact with the crystal surface through supramolecular forces,causing the adaptive closure of voids and the subsequent release of vip molecules.Unlike conventional sponges that rely on mechanical squeeze to deform themselves in the bulk for vip release,these macrocycle crystals undergo structural deformation at the molecular level and condensed phase when exposed to vaporized molecules.Because of the similar behavior between sponges and such NACs,the authors name them as sponge-likemacrocyclecrystals.展开更多
The investigation of thermal transport properties of materials has become increasingly important in technological applications,including thermal management and energy conversion.Recently,ultrahigh or low thermal condu...The investigation of thermal transport properties of materials has become increasingly important in technological applications,including thermal management and energy conversion.Recently,ultrahigh or low thermal conductivity has been reported in nitride,boride,and chalcogenide by different strategies.However,the strategy to design oxide crystals with unique thermal properties is also a challenge.In this work,a new ternary oxide crystal Ga_(2)TeO_(6) is designed and expected to show high thermal conductivity due to its lone pairs-free octahedra connected along the caxis by sharing edges.The thermal conductivities of Ga_(2)TeO_(6) crystal are determined to be 19.2 and 23.9Wm^(-1) K^(-1) along the a-and c-axis directions at 323 K,respectively,which are significantly higher than those of most reported oxide crystals.First-principles calculations and crystal structure analyses reveal that the Ga_(2)TeO_(6) crystal shows high sound velocity and weak lattice anharmonicity due to lone pairs-free octahedra and highly symmetric group arrangement.The results suggest that much attention must be paid to the polyhedron with lone pairs and its arrangement in materials design to balance the functions and thermal properties.展开更多
During the tungsten inert gas(TIG)welding process of Ti_(2)AlNb alloy,high heat input leads to the formation of coarse grains,which are detrimental to the mechanical properties of welded joints.To address this problem...During the tungsten inert gas(TIG)welding process of Ti_(2)AlNb alloy,high heat input leads to the formation of coarse grains,which are detrimental to the mechanical properties of welded joints.To address this problem,Ta microalloyed welding wires were developed to enhance the strength of the welded joints.The Ta-modifed fusion zone(FZ)exhibited a well-defned structure with a smooth,defect-free surface.Systematic analysis of the microstructure evolution and mechanical properties of the welded joints revealed that the Ta element completely dissolves into the FZ.During solidifcation,a signifcant constitutional undercooling efect occurs,promoting the columnar-to-equiaxed transition(CET)and reducing grain size from 187.42 to 133.49μm.Mechanical properties tests indicated that with increased Ta content,the strength of the welded joints initially increased and then decreased.When the Ta content in the welding wire was 1 wt%,the joints showed the best performance,with a tensile strength of 909.36 MPa and an elongation of 1.21%.Compared to the welded samples without Ta,the tensile strength and elongation increased by 153.01 MPa and 0.53%,respectively.Grain refnement and increased dislocation density were the main reasons for the improved mechanical properties.However,excessive Ta content led to signifcant the intragrain misorientation,increasing the joint’s anisotropy and causing uneven deformation during tensile testing.Therefore,further addition of Ta did not substantially enhance the tensile properties of the joint.Additionally,the paper provides a detailed analysis of the low elongation observed in the joint.After welding,dislocations were neatly arranged in the FZ,forming numerous parallel dislocation walls,leading to local stress concentration and accelerating crack initiation and propagation.Consequently,the elongation at the weld was lower than that of the base metal(BM).This research ofers a new approach to improve the mechanical properties of Ti2AlNb alloy during welding.展开更多
文摘In this work, a simulated aircraft fuel tank inerting system has been successfully estab- lished based on a model tank. Experiments were conducted to investigate the influences of different operating parameters on the inerting effectiveness of the system, including flow rate of the inert gas （nitrogen-enriched air）, inert gas concentration, fuel load of the tank and different inerting approaches. The experimental results show that under the same operating conditions, the time span of a complete inerting process decreased as the flow rate of inert gas was increased; the time span using the inert gas with 5% oxygen concentration was much longer than that using pure nitrogen; when the fuel tank was inerted using the ullage washing approach, the time span increased as the fuel load was decreased; the ullage washing approach showed the best inerting performance when the time span of a complete inerting process was the evaluation criterion, but when the decrease of dissolved oxygen concentration in the fuel was also considered to characterize the inerting effective- ness, the approach of ullage washing and fuel scrubbing at the same time was the most effective.
基金supported by National Natural Science Foundation of China Civil Aviation Joint Fund (No.U1933121)Postgraduate Research & Practice Innovation Program of Jiangsu Province (No.KYCX19_0198)The Fundamental Research Funds for the Central Universities and Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘The properties of aviation fuel have a great influence on the performance of oxygenconsuming inerting systems. Based on the establishment of the catalytic inerting process, the flow relationship of each gas component flowing through the catalytic reactor was derived. The mathematical model of the gas concentration in the gas phase of the fuel tank was established based on the mass conservation equation, and the fuel tank model was verified by performing experiments.The results showed that the fuel type exerts a considerably higher influence on the performance of the oxygen-consuming inerting system compared to the corresponding influence on the hollow fiber membrane system, and the relative magnitude of the inerting rates of the four fuel types is RP5 > RP3 > RP6 > JP8. In addition, a higher catalytic efficiency or fuel load rate corresponds to a higher rate of decrease of the oxygen concentration in the gas phase, and the inerting time is inversely proportional to the suction flow rate of the fan. When different fuels are used, the amount of cooling gas and water released from the inerting system are different. Therefore, the influence of fuel type on the system performance should be extensively considered in the future.
基金supported by Funding of Jiangsu Innovation Program for Graduate Education of China (No.KYLX15_0231)Postgraduate Research & Practice Innovation Program of Jiangsu Province of China (No.KYCX17_0279)+1 种基金the Fundamental Research Funds for the Central Universities,Aviation Industry Corporation of China Technology Innovation Fund for Fundamental Research (No.2014D60931R)Funding of Ministry of Industry and Information Technology for Civil Aircraft
文摘Fuel tank inerting technologies are able to reduce the fire risk by injection of inert gas into the ullage or fuel, the former called ullage washing and the latter fuel scrubbing. The Green On-Board Inert Gas Generation System（GOBIGGS） is a novel technology based on flameless catalytic combustion, and owning to its simple structure and high inerting efficiency, it has received a lot of attentions. The inert gas in the GOBIGGS is mainly comprised of CO2, N2, and O2（hereinafter, Mixed Inert Gas（MIG））, while that in the On-Board Inert Gas Generation System（OBIGGS）, which is one of the most widely used fuel tank inerting technologies, is NitrogenEnriched Air（NEA）. The solubility of CO2 is nearly 20 times higher than that of N2 in jet fuels,so the inerting capability and performance are definitely disparate if the inert gas is selected as NEA or MIG. An inerting test bench was constructed to compare the inerting capabilities between NEA and MIG. Experimental results reveal that, if ullage washing is adopted, the variations of oxygen concentrations on the ullage and in the fuel are nearly identical no matter the inert gas is NEA or MIG. However, the ullage and dissolved oxygen concentrations of MIG scrubbing are always higher than those of NEA scrubbing.
基金supported in part by the Shanghai Municipal Science and Technology Major Project (2021SHZDZX0100)Shanghai Municipal Commission of Science and Technology Project (19511132101)National Natural Science Foundation of China (62088101, 61720106011, and 62173034)
文摘1.Introduction Artificial intelligence(AI)is a rapidly growing field of technol-ogy,which“will enliven inert objects,much as electricity did more than a century ago.Everything that we formerly electrified will now cognitize”[1].AI advances are constantly pushing the frontier of what machines can do.Increased attention is being placed on AI research,as well as its development and deployment by commer-cial investors,defense strategists,and policy makers[2].
基金This work was supported by the National Basic Research Program of China(No.2005CB623703)National Natural Science Foundation(No.5047405I)+1 种基金Hunan Provincial Natural Science Foundation of China(No.03JJY3080)Trans-Century Excellent Persons Cultivation Project of Ministry of Education of China(in 2002).
文摘The thermal stresses relaxation of Ni/NiFe2O4 system functionally graded cermet inert anode for aluminum electrolysis was optimally designed. The transient thermal stresses of the inert anode under complex boundary condition during high-temp （955℃） electrolysis were calculated using the finite-element software ANSYS, the influence of different parameters on the distribution of the thermal stresses were analyzed. The results showed that, during the process of thermal shock, the thermal hoop tensile stress on the surface of the anode is very large, which is possibly the major cause of anode crack; when the radius of the anode is between 0.05-0.15m, a range that can be realized by recent manufacturing technology, the optimum composition distribution exponent p is 0.25; The hoop tensile stresses reduce with the decrease of anode scale and also decrease with the decrease of the convection coefficient between the electrolyte and the anode.
基金Project supported by the National Natural Science Foundation of China (Nos. 12172153 and51805216)the China Postdoctoral Science Foundation (No. 2023M731668)the Major Project of Basic Science (Natural Science) of the Jiangsu Higher Education Institutions of China(No. 22KJA410001)。
文摘Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to enhance the dynamic performance. The X-structure is used as a mechanism to realize the nonlinear stiffness characteristic of the NES, which can realize the flexibility, adjustability, high efficiency, and easy operation of nonlinear stiffness, and is convenient to apply in the vehicle suspension, and the inerter is applied to replacing the mass of the NES based on the mass amplification characteristic. The dynamic model of the half-vehicle system coupled with the IX-NES is established with the Lagrange theory, and the harmonic balance method(HBM) and the pseudo-arc-length method(PALM) are used to obtain the dynamic response under road harmonic excitation. The corresponding dynamic performance under road harmonic and random excitation is evaluated by six performance indices, and compared with that of the original half-vehicle system to show the benefits of the IX-NES. Furthermore, the structural parameters of the IX-NES are optimized with the genetic algorithm. The results show that for road harmonic and random excitation, using the IX-NES can greatly reduce the resonance peaks and root mean square(RMS) values of the front and rear suspension deflections and the front and rear dynamic tire loads, while the resonance peaks and RMS values of the vehicle body vertical and pitching accelerations are slightly larger.When the structural parameters of the IX-NES are optimized, the vehicle body vertical and pitching accelerations of the half-vehicle system could reduce by 2.41% and 1.16%,respectively, and the other dynamic performance indices are within the reasonable ranges.Thus, the IX-NES combines the advantages of the inerter, X-structure, and NES, which improves the dynamic performance of the half-vehicle system and provides an effective option for vibration attenuation in the vehicle engineering.
基金Project supported by the National Natural Science Foundation of China(Nos.12172233 and U1934201)。
文摘The dynamic vibration absorber with inerter and grounded stiffness(IGDVA)is used to control a two-scale system subject to a weak periodic perturbation.The vibration suppression effect is remarkable.The amplitude of the main system coupled with absorber is significantly reduced,and the high frequency vibration completely disappears.First,through the slow-fast analysis and stability theory,it is found that the stability of the autonomous system exerts a notable regulating effect on the vibration response of the non-autonomous system.After adding the dynamic vibrator absorber,the center in the autonomous system changes to an asymptotically stable focus,consequently suppressing the vibration in the non-autonomous system.Further research reveals that the parameters of the absorber affect the real parts of the eigenvalues of the autonomous system,thereby regulating the stability of the system.Transitioning from a qualitative standpoint to a quantitative approach,a comparison of the solutions before and after the introduction of the dynamic absorber reveals that,when the grounded stiffness ratio and the mass ratio of the dynamic absorber are not equal,the high-frequency part in the analytical solution disappears.As a result,this leads to a reduction in the amplitude of the trajectory,achieving a vibration reduction effect.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant Nos.2019EEVL03,2019D14 and 2020EEEVL0401National Natural Science Foundation of China under Grant No.51978525National Key R&D Program of China 2021YFE0112200。
文摘When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural durability and ensure the users′comfort level.This study proposed an inerter-based optimal solution to suppress the vibrational forces and energy transmitted to the supporting ground by utilizing the great potential of the inerter.For the external force,which contains various frequency bands,the stochastic response and an energy balance analysis are conducted to evaluate the force transmissibility,structural displacement,and vibration power flow.Given the benefits of the inerter,a transmitted-force-based optimal design framework is proposed for inerter systems,of which the effectiveness is validated by numerical examples.The obtained results show that inerter systems are capable of providing significant reductions in the structural displacement and the force transmitted to the supporting ground.Particularly,the closed-form power equation indicated that a grounded inerter can suppress the force transmission and vibrational energy,thus leading to a less negative impact on the ground and environment.Revealing the working mechanism and optimal design strategy of the inerter can help solve the force-transmission control problem experienced by some practical structures.
文摘In the presence of ethyl alcohol or emulsifier OP,molybdenum(Ⅵ) forms 1∶1∶1'water soluble colored coordination com- pound with both of 2-(2-thiazolylazo)-5-diethylaminophenol (abbreviation TAE) and hydroxylamine.This deep blue coordination compound is inert characteristically and remains stable in 1.7 mol/L sulfuric acid,2.4 mol/L hydrochloric or ni- tric acid.It will not be decomposed by masking agents even on boiled,while in that case,almost all the colored coordination com- pounds formed by other metal ions will be decomposed completely.This inert character of the coordination compound of molybdenum(Ⅵ) and its utilization in improving the analytical selectivity have been discussed.In the coexistence of various for- eign ions,especially in the presence of a great quantity of tungsten,which always interferes with the determination of molybdenum,the direct determination of molybdenum in the aqueous solution by applying this system has shown an acceptable sensitivity and reproducibility.From the results of determination in some synthetic and standard samples,it seems feasible to use this system in the determination of molybdenum in nonferrous alloys.
文摘Inert gas-clustered systems (Xn, X = He, Ne, Ar and n = 2 - 20) were established in this study and their stability as a result of interparticulate interaction was examined. Ferric chloride and ferrous oxides were used as catalysts to promote reaction, and 5-nitro-1,2,4-triazol-3-one (NTO) was theoretically synthesized under an inert gas (X6)-clustered environment in this study. The raw material, urea, initially underwent chlorination using chlorine as the reagent, followed by amination, formylation and nitration. Reaction routes closely related to the experimental processes were successfully constructed, and the corresponding energy barriers were estimated for each elementary reaction. The findings revealed that the average errors in the B3LYP/6-31G(d, p)-calculated geometry and vibrational frequency of NTO in an Ne6 system relative to the observed values were 0.83% and 1.84%, respectively. The neon gas-clustered system achieved greater stabilization, which results from the difference in self-consistent field energy (ESCF), than the corresponding stabilization acquired in a helium- or argon-based system. Ferric chloride serves as a good catalyst to reduce the energy barrier of the chlorination reaction, and ferrous oxide is suitable for catalyzing the amination, formylation and nitration reactions, although nitric acid is the better agent for nitration. The catalytic Ne6-clustered reaction system is suggested to be a more feasible pathway for the synthesis of NTO.
基金support from the National Natural Science Foundation of China(No’s.U22B2071,51874211,52031008)the Chilwee Group(CWDY-ZH-YJY-202101-001).
文摘Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-carbon emissions and no chlorine gas evolution.The clean production stems from the choice of a molten NaCl-Na_(2)CO_(3) electrolyte to prevent chlorine gas evolution,an inert nickel-based anode to produce oxygen,and a liquid metal cathode to make the cathodic product sit at the bottom of the electrolytic cell.We achieve a current efficiency of>90%for the electrolytic production of liquid Na-Sn alloy.Later,Mg-Sn alloy is prepared using the obtained Na-Sn alloy to displace Mg from molten NaCl-MgCl_(2) with a displacement efficiency of>96%.Further,Na and Mg are separated from the electrolytic Na-Sn and displaced Mg-Sn alloys by vacuum distillation with a recovery rate of>92%and Sn can be reused.Using this electrolysisdisplacement-distillation(EDD)approach,we prepare Mg from seawater.The CO_(2)emission of the EDD approach is~20.6 kg CO_(2)per kg Mg,which is less than that of the Australian Magnesium(AM)electrolysis process(~25.0 kg CO_(2)per kg Mg)and less than half that of the Pidgeon process(~45.2 kg CO_(2)per kg Mg).
基金financially supported by the Science and Technology Innovation Program of Hunan Province,China(No.2023RC3055)the Natural Science Foundation of Hunan Province,China(Nos.2023JJ30671,2020JJ4114)+5 种基金the Natural Science Foundation of Changsha City,China(No.Kq2208264)National Key Project of Research and Development Plan of China(Nos.2021YFC1910505,2021YFC1910504)the Young Core Teacher Foundation of Hunan Province,China(No.150220001)Key Research and Development Program of Guangdong Province,China(No.2020B010186002)the National Natural Science Foundation of China(No.51601229)the Key-Area Research and Development Program of Foshan City,China(No.2230032004640).
文摘The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.
基金financially supported by Hunan Provincial Science and Technology Department,China(No.2021JJ10058)Key Research and Development Program of Hunan Province,China(No.2023GK2016)。
文摘A dual-halide solid electrolyte,Li_(3)YCl_(3)Br_(3),was synthesized using a wet-chemistry route instead of the conventional mechanical ball-milling route.Li_(3)YCl_(3)Br_(3) exhibits an ion conductivity of 2.08 mS/cm and an electro-chemical stability window of 3.8 V.Additionally,an all-solid-state lithium-ion battery using Li_(3)YCl_(3)Br_(3) and LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(NCM811)as the cathode material achieves a capacity retention of 93%after 200 cycles at 0.3C and maintains a specific capacity of 115 mA·h/g during 2C cycling.This exceptional performance is attributed to the high oxidative stability of Li_(3)YCl_(3)Br_(3) and the in-situ formation of Y_(2)O_(3) inert protective layer on the NCM811 surface under high voltage.Consequently,the study demonstrates the feasibility of a simple,cost-effective wet-chemistry route for synthesizing multi-component halides,highlighting its potential for large-scale production of halide solid electrolytes for practical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102015 and 12472003)the General Program of Science and Technology Development Project of the Beijing Municipal Education Commission(Grant No.KM202110005030)the Key Research Project of Zhejiang Market Supervision Administration(Grant No.ZD2024013).
文摘The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial nonlinear energy sink(NES)is applied for the first time to achieve vibration suppression in beams under moving loads.Based on the Timoshenko beam theory,the nonlinear motion equations of a beam with an inertial NES are derived using the energy method and Lagrange equations.The Newmark-βmethod combined with the Heaviside step function is adopted to calculate the responses of the beam under moving loads of constant amplitude and harmonic excitation.The accuracy of the modelling derivation and solution methodology are validated through comparisons with results from other studies.The results demonstrate that the velocity and excitation frequency of the moving load significantly affect the response of the beam as well as the performance of the inertial NES.To enhance its effectiveness under various moving load conditions,parametric optimization is numerically performed.The optimized inertial NES can achieve good performance by efficiently reducing the maximum deflection of the beam.The findings of this study contribute to advancing the understanding and application of NESs in mitigating structural vibrations caused by moving loads.
基金supported by the National Natural Science Foundation of China(Grant Nos.62203076,62103065,61922053,62325302,and U2013202)China Postdoctoral Science Foundation(Grant Nos.2021M700584 and 2022M710514)+2 种基金Program of Shanghai Academic/Technology Research Leader(Grant No.21XD1421400)Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyjzdxmX0014)the“Shuguang Program”(18SG36)supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission.
文摘Nonlinear characteristics have demonstrated significant advantages in mitigating vibrations across various engineering applications,particularly in effectively suppressing vibrations over a wide frequency range.This paper introduces a novel nonlinear energy sink with a magnetic inerter(MINES).The MINES features a magnetic lead screw that incorporates a pair of helical permanent magnets.When the inner part undergoes linear motion,it is transformed into the rotation of the outer part at a predetermined conversion ratio.Subsequently,the MINES is incorporated into a system with a single degree of freedom,and the corresponding differential equations of motion are derived.The approximate analytical method and the numerical method are used to validate each other.This process clarifies the effectiveness of the MINES in reducing vibrations when subjected to harmonic excitation.The influence of the parameters of the MINES is analyzed.The findings demonstrate that the MINES offers significant benefits in terms of vibration suppression efficiency when the depths of the three barriers are equal.Furthermore,with the increase in excitation amplitude,the MINES enters the nonlinear range,leading to a reduction in system damping.This can effectively prevent the phenomenon of traditional damping stiffening under conditions of high amplitude excitation.Finally,the vibration reduction capability of this nonlinear energy sink was experimentally demonstrated,enhancing its applicability in vibration mitigation.
基金supported by the National Defense Basic Research Program of China(No.JCKY2023204A005)the Research Program of Joint Research Center of Advanced Spaceflight Technologies of China(No.USCAST2023-3)+2 种基金the National Natural Science Foundation of China(No.U2037601)the Major Scientific and Technological Innovation Project of Luoyang,Henan Province,China(No.2201029A)the Foundation Strengthening Plan Technical Field Fund,China(No.2021-JJ-0112).
文摘Tungsten inert gas(TIG)welding and laser beam welding(LBW)were employed on as-cast and as-forged Mg−8Li−3Al−2Zn−0.5Y(LAZ832-0.5Y)alloys to investigate their weldability.The microstructure and mechanical properties of solid solution treated samples were investigated for the purpose of further strength improvement,which were treated at 350℃ for 4 h.The ultimate tensile strength(UTS)and yield strength(YS)of the optimal TIG as-cast alloy welding joint were 159 and 122 MPa,which were obtained under the welding current of 80 A,and were lower than the UTS(184 MPa)and YS(146 MPa)of the optimal LBW as-forged welding joint under the power of 2.1 kW/2.0 kW double-side welding.After the solid solution treatment,on the one hand,the growth ofα-Mg grains in the fusion zone(FZ),heat affected zone(HAZ)and base metal(BM)of both the TIG and LBW welding joints was insignificant.On the other hand,the larger Al_(2)Y phases were still present,while the much smaller white AlLi particles were dissolved into the matrix,leading to the solid solution strengthening of the welding joints.As a result,the UTS and YS of the TIG welding joint respectively increased to 216 and 188 MPa after solid solution treatment,and those of the LBW welding joint only increased to 211 and 160 MPa,respectively.
基金Project(2024BAB094)supported by the Key Research and Development Program of Hubei Province,ChinaProject(2024040801020296)supported by the Natural Science Foundation of Wuhan City,ChinaProject(52276113)supported by the National Natural Science Foundation of China。
文摘CaO-based heat carriers have shown great prospects for thermochemical energy storage in concentrated solar power systems due to the features such as rich reserves,environmental safety,high energy storage densities and high operation temperatures.However,the density decay because of sintering and poor direct solar absorption of white CaO based heat carriers are the two main obstacles lying on the way to the realistic applications.This work introduced dark Mn-based inert support into calcium heat carriers,attempting to solve the above problems simultaneously.As an inert support,the finely dispersed Ca_(2)MnO_(4) functioned as the metal framework to resist CaCO_(3)/CaO sintering.Consequently,the cyclic stability of CaO-based heat carriers,resulting in the high energy storage densities of~2000 kJ/kg even over 20 cycles.As a dark material,Ca_(2)MnO_(4) successfully darkened CaO-based heat carriers,thereby greatly enhanced the direct solar absorption.In addition,the granulation of CaO-based heat carriers was also studied.The pellets showed satisfactory attrition resistance with only 9.85 wt% mass loss over 3200 cycles.In general,good physicochemical performance of Mn-doped CaO-based heat carrier endows it with great prospects for solar energy storage.
基金the Natural Science Foundation of Jiangsu Province(No.BK20240679)National Natural Science Foundation of China(No.22101134)are greatly acknowledged。
文摘Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operational costs,particularly for hydrocarbons with high boiling points or strong host-vip interactions[2].This is the same case in the newly-developed macrocyclebased crystalline adsorbents,namely nonporous adaptive crystals(NACs).To address these challenges,a recent study published in Angewandte Chemie International Edition by Jie,Ma,and co-workers reported an innovative molecular-"squeeze"triggered desorption mechanism in NACs[3-5].Specifically,ethyl acetate(EA)triggers vip desorption without penetrating the crystal pores or voids.Instead,EA molecules interact with the crystal surface through supramolecular forces,causing the adaptive closure of voids and the subsequent release of vip molecules.Unlike conventional sponges that rely on mechanical squeeze to deform themselves in the bulk for vip release,these macrocycle crystals undergo structural deformation at the molecular level and condensed phase when exposed to vaporized molecules.Because of the similar behavior between sponges and such NACs,the authors name them as sponge-likemacrocyclecrystals.
基金supported by the National Natural Science Foundation of China(No.62175129)the Taishan Scholar of Shandong Province(No.tsqn202306014)the Qilu Young Scholar of Shandong University.
文摘The investigation of thermal transport properties of materials has become increasingly important in technological applications,including thermal management and energy conversion.Recently,ultrahigh or low thermal conductivity has been reported in nitride,boride,and chalcogenide by different strategies.However,the strategy to design oxide crystals with unique thermal properties is also a challenge.In this work,a new ternary oxide crystal Ga_(2)TeO_(6) is designed and expected to show high thermal conductivity due to its lone pairs-free octahedra connected along the caxis by sharing edges.The thermal conductivities of Ga_(2)TeO_(6) crystal are determined to be 19.2 and 23.9Wm^(-1) K^(-1) along the a-and c-axis directions at 323 K,respectively,which are significantly higher than those of most reported oxide crystals.First-principles calculations and crystal structure analyses reveal that the Ga_(2)TeO_(6) crystal shows high sound velocity and weak lattice anharmonicity due to lone pairs-free octahedra and highly symmetric group arrangement.The results suggest that much attention must be paid to the polyhedron with lone pairs and its arrangement in materials design to balance the functions and thermal properties.
基金supported by the National Natural Science Foundation of China(No.52171041)the Science and Technology Special Project(K19168).
文摘During the tungsten inert gas(TIG)welding process of Ti_(2)AlNb alloy,high heat input leads to the formation of coarse grains,which are detrimental to the mechanical properties of welded joints.To address this problem,Ta microalloyed welding wires were developed to enhance the strength of the welded joints.The Ta-modifed fusion zone(FZ)exhibited a well-defned structure with a smooth,defect-free surface.Systematic analysis of the microstructure evolution and mechanical properties of the welded joints revealed that the Ta element completely dissolves into the FZ.During solidifcation,a signifcant constitutional undercooling efect occurs,promoting the columnar-to-equiaxed transition(CET)and reducing grain size from 187.42 to 133.49μm.Mechanical properties tests indicated that with increased Ta content,the strength of the welded joints initially increased and then decreased.When the Ta content in the welding wire was 1 wt%,the joints showed the best performance,with a tensile strength of 909.36 MPa and an elongation of 1.21%.Compared to the welded samples without Ta,the tensile strength and elongation increased by 153.01 MPa and 0.53%,respectively.Grain refnement and increased dislocation density were the main reasons for the improved mechanical properties.However,excessive Ta content led to signifcant the intragrain misorientation,increasing the joint’s anisotropy and causing uneven deformation during tensile testing.Therefore,further addition of Ta did not substantially enhance the tensile properties of the joint.Additionally,the paper provides a detailed analysis of the low elongation observed in the joint.After welding,dislocations were neatly arranged in the FZ,forming numerous parallel dislocation walls,leading to local stress concentration and accelerating crack initiation and propagation.Consequently,the elongation at the weld was lower than that of the base metal(BM).This research ofers a new approach to improve the mechanical properties of Ti2AlNb alloy during welding.
