Because the bonding interface of dissimilar metal joint between AZ31 B Mg alloy and DP600 galvanized steel by keyholeless friction stir spot welding(KFSSW)is permanent bonding,the interface morphology cannot be direct...Because the bonding interface of dissimilar metal joint between AZ31 B Mg alloy and DP600 galvanized steel by keyholeless friction stir spot welding(KFSSW)is permanent bonding,the interface morphology cannot be directly observed.If the joint is separated by external force,the original features of bonding interface of joint will be destroyed,which has influence on the accuracy for observation and analysis of the result.In this paper,the coordinates of the key point at the interface of every cross-section at intervals of 0.2 mm were measured and connected into an outline.The outline of all interfaces makes up the three-dimensional morphologies of bonding interface between AZ31 B Mg alloy and DP600 steel by KFSSW,which was constructed by Solidworks software to restore the real mechanical bonding state of joint.Combined with the microhardness analysis of cross-section and results of in-situ tensile test,the unique bonding state and morphology of Mg and steel in the welded joint were confirmed.展开更多
In rock engineering,the shear strength of the basalt-concrete bonding interface is a key factor affecting the shear performance of hydroelectric dam foundations,embedded rock piles and rock bolts.In this study,30 sets...In rock engineering,the shear strength of the basalt-concrete bonding interface is a key factor affecting the shear performance of hydroelectric dam foundations,embedded rock piles and rock bolts.In this study,30 sets of in-situ direct shear tests were conducted on the basalt-concrete bond interface in the Baihetan dam area to investigate the shear strength characteristics of the basalt-concrete bonding interface.The bonding interface contains two states,i.e.,the bonding interface is not sheared,termed as se(symbolic meaning see Table 1);the bonding interface is sheared with rupture surface,termed as si.The effects of lithology,Joints structure,rock type grade and concrete compressive strength on the shear strength of the concrete-basalt contact surface were investigated.The test results show that the shear strength of the bonding interface(s_(e)&s_(i))of columnar jointed basalt with concrete is greater than that of the bonding interface(s_(e)&s_(i))of non-columnar jointed one with the same rock type grade.When the rock type grade isⅢ_(2),fcol is 1.22 times higher than fncol and ccol is 1.13 times greater than cncol.The shear strength parameters of the basalt-concrete bonding interface differ significantly for different lithologies.The cohesion of the bonding interface(s_(i))of cryptocrystalline basalt with concrete is 2.05 times higher than that of the bonding interface(s_(i))of breccia lava with concrete under the same rock type grade condition.Rock type grade has a large influence on the shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i)).cnol increases by 33%when the grade of rock type rises fromⅢ_(1)toⅡ_(1).the rock type grade has a greater effect on bonding interface(s_(i))cohesion than the coefficient of friction.When the rock type grade is reduced fromⅢ_(2)toⅢ_(1),f_(ncol)′increases by 2%and c_(ncol)′improves by 44%.The shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i))increases with the increase of the compressive strength of concrete.When concrete compressive strength rises from 22.2 to 27.6 MPa,the cohesion increases by 94%.展开更多
Complete understanding of the evolution behaviors of the microstructures and intermetallic compounds(IMCs)along the interface materials flow path in friction stir welding(FSW)of dissimilar Al to Mg alloys is of great ...Complete understanding of the evolution behaviors of the microstructures and intermetallic compounds(IMCs)along the interface materials flow path in friction stir welding(FSW)of dissimilar Al to Mg alloys is of great significance.In this study,conventional FSW and ultrasonic vibration enhanced FSW(UVeFSW)experiments of Al/Mg alloys were performed,and the instantaneous evolution features of the interface materials around the tool were"frozen"by using the"sudden stop"and simultaneous cooling techniques.The microstructures and IMCs formation at different locations around the exit hole were observed and characterized by scanning electron microscope,energy dispersive spectrometer and transmission elec-tron microscope.It was found that before the materials started to deposit near the back of the tool,“IMC+Mg+IMC+Al”multilayer microstructure and simple IMC layer with(β+γ)sequentially emerged on the Al/Mg interface.With the application of ultrasonic vibration,the multi-layered interface structure only appeared at the middle stage of materials flow around the pin,and ultrasonic vibration just began to play a suppression role on the growth of two sub-layers IMC at a position where the materials deposit.With assistance of ultrasonic vibration in UVeFSW,the tool drove a larger volume of Mg alloy to move toward the retreating side,and the final IMCs thickness was thinner than that in FSW.展开更多
This study focuses on the bonding interface characteristics and mechanical properties of the bobbin tool friction stir welded dissimilar AA6056 and AA2219 aluminum alloy joints using diff erent welding speeds.Voids ar...This study focuses on the bonding interface characteristics and mechanical properties of the bobbin tool friction stir welded dissimilar AA6056 and AA2219 aluminum alloy joints using diff erent welding speeds.Voids arise solely in the stir zone at the AA2219 side.A distinct boundary with limited material mixing develops at the middle section of the bonding interface,while excellent material mixing with an irregularly jagged pattern forms at the top and bottom sections of the bonding interface.Increasing the welding speed,the material mixing is rarely changed at the middle section in comparison with the bottom section.Furthermore,a small diff erence between Guinier–Preston dissolution and Q phase precipitation leads to rare change of hardness in the heat aff ected zone(HAZ)at the AA6056 side.The increased hardness of the HAZ at the AA2219 side is attributed to avoidance of the dissolution ofθ’’phase precipitates.A maximum tensile strength of 181 MPa is obtained at 300 mm min-1.Fractures occur at the AA6056 side near the top and bottom surfaces and at the bonding interface in the middle section of the joints.The regions close to the top and bottom surfaces of the joints show a better ductility.展开更多
Oxygen anion redox reaction provides a high theoretical capacity for Li-rich manganese-based cathodes.However,irreversible surface oxygen release often results in further oxygen loss and exacerbates the decomposition ...Oxygen anion redox reaction provides a high theoretical capacity for Li-rich manganese-based cathodes.However,irreversible surface oxygen release often results in further oxygen loss and exacerbates the decomposition of the electrolyte,which could reduce the capacity contribution from the anionic redox and produce more acidic substances to corrode the surface of the material.In this paper,the surface oxygen release is suppressed by moderating oxygen anion redox activity via constructing chemical bonds between M(M=Fe and La)in LaFeO_(3)and surface oxygen anions of Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2).The constructed interface layer stabilizes the surface lattice oxygen and retards the electrolyte from being attacked by the nucleophilic oxygen generated in the process of oxygen release,as evidenced by Differential Electrochemical Mass Spectrometry(DEMS)and X-ray Photoelectron Spectroscopy(XPS)detections.Moreover,in the charge and discharge process,the formed FeF_(3),located at the cathode electrolyte interfacial layer,is conducive to the stability of the cathode surface.The modified Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2)electrode with 3 wt%LaFeO_(13)exhibits a high specific capacity of 189.5 mA h g-at 1C(200 mA g^(-1))after 150 cycles with capacity retentions of 96.6%,and 112.6 mA h g^(-1)(84.7%)at 5C after 200 cycles higher than the pristine sample.This study provides a rational design chemical bonding method to suppress the oxygen release from the cathode surface and enhance cyclic stability.展开更多
The microstructure, interface thickness, element distribution and interfacial mechanical behavior of Ti-6Al-4V/Al couples prepared by an insert moulding method were investigated in depth in this paper. Moreover, Ti/Al...The microstructure, interface thickness, element distribution and interfacial mechanical behavior of Ti-6Al-4V/Al couples prepared by an insert moulding method were investigated in depth in this paper. Moreover, Ti/Al bonding was also given as a comparison for understanding the interface bonding mechanism. It is shown that there is much thinner compact sub-layer for the interface of the Ti-6Al-4V/Al joint, whose morphology is obviously different from that of the Ti/Al joint. The Ti-6Al-4V/Al interface has been proven to contain a slight content of vanadium. Moreover, both the shear strength and the interface reaction rate of Ti-6Al-4V/Al compound materials are lower than those of the Ti/Al ones.展开更多
Silicon carbide nanofibers grew on the surface of carbon fibers of a unidirectional carbon preform by CCVD and then chemical vapor infiltration was used to densify the preform to get the SiCNF-C/C composite. The effec...Silicon carbide nanofibers grew on the surface of carbon fibers of a unidirectional carbon preform by CCVD and then chemical vapor infiltration was used to densify the preform to get the SiCNF-C/C composite. The effects of silicon carbide nanofibers on the microstructure of the pyrolytic carbon and the thermal conductivity of the SiCNF-C/C composite were investigated. Results show that silicon carbide nanofibers on the surface of carbon fibers induce the deposition of high texture pyrolytic carbon around them. The interface bonding between carbon fibers and pyrolytic carbon is well adjusted. So the efficiency of heat transfer in the interface of the composite is well enhanced. The thermal conductivity of the SiCNF-C/C composite is greater than that of the C/C composite, especially the thermal conductivity perpendicular to the fiber axis.展开更多
Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloy...Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloying/dealloying processes and low electronic conductivity of Si anodes restrict their electrochemical performance.Thus,carbon(C)materials with special physical and chemical properties are applied in Si anodes to effectively solve these problems.This review focuses on current status in the exploration of Si/C anodes,including the lithiation mechanism and solid electrolyte interface formation,various carbon sources in Si/C anodes,such as traditional carbon sources(graphite,pitch,biomass),and novel carbon sources(MXene,graphene,MOFs-derived carbon,graphdiyne,etc.),as well as interfacial bonding modes of Si and C in the Si/C anodes.Finally,we summarize and prospect the selection of carbonaceous materials,structural design and interface control of Si/C anodes,and application of Si/C anodes in all-solid-state lithium-ion batteries and sodium-ion batteries et al.This review will help researchers in the design of novel Si/C anodes for rechargeable batteries.展开更多
The metallurgical bonding quality of bonding joints is affected by the substrate surface state in hot-compression bonding(HCB),and the surface roughness is a core indicator of the surface state.However,the effects of ...The metallurgical bonding quality of bonding joints is affected by the substrate surface state in hot-compression bonding(HCB),and the surface roughness is a core indicator of the surface state.However,the effects of surface roughness on interface bonding performance(IBP)in the HCB process are unclear for substrates with refractory oxide scales.This study presents the effects of surface roughness on IBP for 316H stainless steel joints fabricated by HCB.A set of HCB parameters for interface bonding critical state of 316H stainless steel joints was determined.The HCB experiments were carried out under parameters of interface bonding critical state to amplify the effect of surface roughness.The interface morphologies,element distribution,and tensile properties were used to characterize the IBP.As a result,the formation mechanisms of the interface pits were revealed and the variation trend of pit number with the roughness was summarized.Finally,the mapping relation between surface roughness and IBP was established.The results show that the degree of rotational dynamic recrystallization becomes weaker with the decrease in the surface roughness and the interface bonding mechanism is completely transformed into discontinuous dynamic recrystallization when the roughness is lower than 0.020μm Sa.The number of interfacial pits decreases as the roughness decreases owing to the weakening of oxide scale aggregation and abrasive inclusion mechanism.The elongation of the tensile specimen cannot increase significantly while the roughness is lower than 0.698μm Sa.展开更多
Solid-state diffusion bonding(DB)of TiAl alloy and Ti2 AlNb alloy was carried out using pure Ti as an interlayer at 1000℃under 20 MPa for 60-120 min.The effects of bonding times on the interfacial microstructure and ...Solid-state diffusion bonding(DB)of TiAl alloy and Ti2 AlNb alloy was carried out using pure Ti as an interlayer at 1000℃under 20 MPa for 60-120 min.The effects of bonding times on the interfacial microstructure and mechanical performance of the TiAl/Ti/Ti_(2)AlNb bonded joints at room temperature(RT)were investigated detailly.The results demonstrated that the diffusion layers(DLs)mainly consisted of four characteristic layers,(Ⅰ)single coarseα_(2)phase adjacent TiAl alloy,(Ⅱ)single refinedα_(2)phase at the bonding interface,(Ⅲ)equiaxed/acicularα_(2)phase embedded inβphase adjacent Ti_(2)AtNb alloy and(IV)both equiaxedα_(2)phase and acicular O phase embedded inβphase adj acent Ti_(2)AlNb alloy,respectively.The thickness of the four layers increased with the increasing of the bonding time.The growth of DLs is controlled by diffusion and the reaction rate constant k for regionⅠ,Ⅱ,ⅢandⅣare 1.22×10^(-6),1.27×10^(-6),2.6×10^(-7)and 7.7×10^(-7)m·s^(-1/2),respectively.Meanwhile,the interfaceα_(2)grain grows up without texture.The maximum tensile strength of 281 MPa was maintained at1000℃for 90 min under the pressure of 20 MPa.Consequently,the phase transformation and dynamic recrystallization behavior of the DLs were discussed.展开更多
A large number of scraps are produced in the fabrication process of magnesium alloy products. It is necessary to recycle these scraps for the development and scale application of magnesium alloys. In this research,a m...A large number of scraps are produced in the fabrication process of magnesium alloy products. It is necessary to recycle these scraps for the development and scale application of magnesium alloys. In this research,a method for recycling AZ91D magnesium alloy scraps fabricated by hot-press / extrusion was studied. Mechanical properties and microstructure of the recycled specimens were investigated. Microstructural analyses were performed by using the techniques of optical microscopy and scanning electron microscopy. Microstructural observations reveal that the recycled specimens consisted of fine grains when adopting the extrusion temperature of 400- 450 ℃,the extrusion ratio of( 25- 100) ∶ 1 and the extrusion rate of 0. 10- 0. 20 mm / s. Ultimate tensile strength and elongation to failure increased with the increase of the extrusion temperature,the extrusion ratio and the extrusion rate,respectively. Recycled specimens reached the highest ultimate tensile strength of average 361. 47 MPa and the highest elongation to failure of average 11. 55% when adopting the hot-press,the extrusion temperature of 400± 5 ℃,the extrusion ratio of 100 ∶ 1 and the extrusion rate of 0. 15 mm / s. The shape of bonding interface was tightly relation with the ultimate tensile strength. When the bonding interface formed continuous curves,the ultimate tensile strength decreased almost linearly with increasing the average width of the bonding interface. When the bonding interface formed discontinuous curves,the ultimate tensile strength increased almost linearly with the increase the proportion of the fine bonding length accounting for the measured interface length. Ultimate tensile strength of the recycled specimens could be calculated by using the forecastable equation.展开更多
The consolidation Mg-Gd-Y-Zn-Zr billets containing long period-stacking ordered(LPSO)phase were recycled from the metal chips through the spark plasma sintering(SPS)process,which achieves the effective metallurgical b...The consolidation Mg-Gd-Y-Zn-Zr billets containing long period-stacking ordered(LPSO)phase were recycled from the metal chips through the spark plasma sintering(SPS)process,which achieves the effective metallurgical bonding between metal chips.The effects of the sintering parameters on the microstructure characteristic and mechanical properties of the recycled billets were studied.The metal chips were effectively bonded in the recycled billets sintered at 500°C,however,the metal chips partly melted into semi-solid state as sintering temperature increased to 550°C.The oxidation films of rare earth(RE)element formed at the bond interface between metal chips during SPS recycling process.The consolidation recycled billets through SPS demonstrated the rival compression failure strain and superior compression stress compared with the referenced cast alloy.The lamellar 14H-LPSO phases hardly precipitate in the vicinity of the bond interface between metal chips after heat treatment with air cooling.However,the furnace cooling facilitates the precipitation of 14H-LPSO phases within the a-Mg grains,even the a-Mg matrix adjacent to the bond interface.The oxide films at the bond interface between the metal chips were zigzagged and fragmented during the isothermal compression.The cracks or holes were hardly observed adjacent to the bond interface during isothermal compression,which reveals superior bond properties and deformation consistency performance between metal chips.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.展开更多
The influences of new,scrap,and five modified Mo fibers on interface bonding strength of fiber-matrix and mechanical strength of RMC were studied.Typical specimens with different fibers and mass ratio of resin and har...The influences of new,scrap,and five modified Mo fibers on interface bonding strength of fiber-matrix and mechanical strength of RMC were studied.Typical specimens with different fibers and mass ratio of resin and hardener were prepared to verify the above assumptions.Theoretical analysis and experimental results prove that,compared with ordinary new Mo fibers,scrap Mo fibers can perform better in improving interface bonding strength and mechanical properties of RMC because many discharge pits randomly distribute on the surface of scrap fibers.For five modified Mo fibers,interface bonding strength and the reinforcing effect on RMC have been improved obviously.Wherein,comprehensive mechanical properties of RMC are optimal with the addition of M6 fibers which have undergone combined surface treatment including acidification,gas-phase oxidation and coupling treatment.And interface bonding strength between M6 fiber and matrix is the maximum.展开更多
This study was designed to solve the problem of large waste volume from bamboo processing residues in recent years.Using magnesium oxychloride(MO)cementitious material as the main material and bamboo residue(BR)as the...This study was designed to solve the problem of large waste volume from bamboo processing residues in recent years.Using magnesium oxychloride(MO)cementitious material as the main material and bamboo residue(BR)as the reinforcing material,a BR/MO composite material was prepared.The effects of BR amount on the molding properties,mechanical strength,and water resistance of BR/MO composites were examined and discussed.Scanning electron microscopy(SEM),X-ray diffractometry(XRD),and thermogravimetric analysis were used to characterize composite microscopic morphology,crystalline structure,and heat resistance.The results showed that,when the BR content was 1.00%(by wt),the flowability of MO paste was beneficial to composite molding.Composite mechanical properties and water resistance were greatly affected by BR addition.When the BR content was 1.00%,composite compressive and bending strengths and softening coefficient all reached maximum values.Meanwhile,increases in water absorption by 24 h and decreases of contact angle were small.These results suggested that,when the BR content was 1.00%,composite mechanical properties and water resistance were the best and the mechanical strength also improved with extended composite storage time.SEM analysis indicated that BR played the role of a reinforcing phase in MO matrices.However,when the BR content exceeded 1.00%,interfacial bonding between BR and MO became less.XRD analysis showed that,with 1.00%BR content,composites showed more 5-phase crystals with high strength.This further explained the reason why this composite’s mechanical properties were the best and the heat resistance not deteriorated due to BR,which was easily decomposed.展开更多
Inspired by the multi-layer architecture of mammal skins,interfacial robust,stretchable,and entirely healable gel-elastomer hybrids hold great potential in diverse fields including biomedical devices,wearable electric...Inspired by the multi-layer architecture of mammal skins,interfacial robust,stretchable,and entirely healable gel-elastomer hybrids hold great potential in diverse fields including biomedical devices,wearable electrical devices,and soft robotics.However,existing gel-elastomer hybrids have numerous limitations including low interfacial bonding toughness,complex and time-consuming preparation process,unhealable,and non-reconfiguration.Herein,we propose a simple and general chemical strategy through the interfacial dynamic bonding between gel and elastomer to simultaneously address the abovementioned obstacles.Dynamic covalent bonds readily and repeatably covalent bonding ionogel and elastomer(interfacial toughness:390 J m^(-2)),endowed the hybrids with entire self-healing features like skin and enabled discretionary assembly and reconfiguration.Moreover,this strategy resolved the troublesome contradiction between interfacial stability and reconfiguration.Taking advantage of the aforementioned features,we readily constructed a multi-module,self-healing,self-powered,and realtime monitoring of personal status integrated elastic electronics,which could simply reconfigure the output signal of elastic electronics into an input signal of the devices-braille keyboard.展开更多
Facile and ecofriendly loading of micro/nano function-specific substances to create functional materials is a trend being pursued by researchers.However,current micro/nano particles loading approaches are often hinder...Facile and ecofriendly loading of micro/nano function-specific substances to create functional materials is a trend being pursued by researchers.However,current micro/nano particles loading approaches are often hindered by issues such as uneven distribution,unsatisfactory stability and complicate procedure.In this work,we present an aqueous phase reshaping method that only utilizes the moisture to fabricate the"bubble particles",which could perfectly cater to the topography of the substrate.The green preparation of bubble particles adopts an absolutely zero-pollution method,realizing the firm loading of particles on the substrate.Integrating the preparation and loading of particles overcomes the traditional complicate process,while the aqueous phase reshaping ensures uniform and firm loading of the"bubble particles"onto the substrate.Our mechanism demonstrates a significant enhancement in the interface relation after aqueous phase reshaping,with a 121-fold increase in contact surface area achieved by reducing the height by 1μm.Furthermore,we explore for the first time the influence of the nature of the receiving substrate on the interface morphology of particles during electrostatic spraying,which has important guiding significance for the interface relationship of electrostatic spraying and even electrostatic spinning materials.We also screen out the natural antibacterial essential oil linalool as the effective specialized antibacterial agent,which can specifically inhibit the odor-producing Proteus in urine,with an antibacterial rate of up to 100%.Taken together,this simple,ecofriendly method for fabricating functional materials with optimal interface stability appears highly promising for use in various products formed by electrostatic spraying/spinning.展开更多
The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength ...The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength in metal matrix composites. In this study, citric acid was employed as the precursor for synthesizing multiscale carbon nanomaterials(graphene quantum dots and graphene, abbreviated as GQDs and GN). The GQDs@GN/Cu composites were fabricated through a segmented ball milling process in conjunction with subsequent spark plasma sintering(SPS). The intragranular GQDs and intergranular GQDs@GN had synergistically reinforced Cu composites through Orowan strengthening, load transfer strengthening and refinement strengthening. Furthermore,the robust interface bonding between GQDs@GN and Cu effectively mitigated interfacial impedance stemming from electron-boundary scattering. The yield strength and ultimate tensile strength of the GQDs@GN/Cu composites were recorded as 270 and 314 MPa, respectively, representing an improvement of 92 and 28% over pure Cu, while maintaining electrical conductivity at a level comparable to that of pure Cu. This study advances the understanding of the possibility of realizing a synergistic compatibility between electrical conductivity and mechanical strength in Cu composites.展开更多
Transition metal carbide/nitride cores within MXenes make them considerably useful for ultra-high-temperature reinforcement.However,extensive research on Ti_(3)C_(2)T_(x) MXene has revealed its tendency to undergo a p...Transition metal carbide/nitride cores within MXenes make them considerably useful for ultra-high-temperature reinforcement.However,extensive research on Ti_(3)C_(2)T_(x) MXene has revealed its tendency to undergo a phase transition to TiCy at temperatures above 800℃due to high activity of a superficial Ti atomic layer.Herein,spark plasma sintering of Ti_(3)C_(2)T_(x) and TiC is performed to prevent the Ti_(3)C_(2)T_(x) phase transition at temperatures up to 1900℃through the fabrication of composites at a pressure of 50 MPa.Using a focused ion beam scanning electron microscope to separate layered substances in the composites and examining selected area diffraction spots in a transmission electron microscope enabled identification of non-phase-transitioned MXene.First-principles calculations based on density functional theory indicated the formation of strong chemical bonding interfaces between Ti_(3)C_(2)T_(x) and TiC,which imposed a stability constraint on the Ti atomic layer at the Ti_(3)C_(2)T_(x) surface.Mechanical performance tests,such as three-point bending and fracture toughness analysis,demonstrated that the addition of Ti_(3)C_(2)T_(x) can effectively improve the cross-scale strengthening and toughening of the TiC matrix,providing a new path for designing and developing two-dimensional(2D)carbides cross-scale-enhanced three-dimensional(3D)carbides with the same elements relying on a wide variety of MXenes.展开更多
Carbide-dispersion strengthened(CDS)vanadium alloy is a kind of advanced structural material for V/Li fusion blanket.The welding technology for the alloy is very important for its application in fusion reactors.In the...Carbide-dispersion strengthened(CDS)vanadium alloy is a kind of advanced structural material for V/Li fusion blanket.The welding technology for the alloy is very important for its application in fusion reactors.In the present study,preliminary investigation on dissimilar-metal bonding by hot isostatic pressing(HIP)was carried out for the CDS V alloy by joining with the conventional V-4Cr-4Ti alloy.Microstructural characterization for the bonding interfaces and mechanical tests for bonding property evaluation were analyzed for the HIP joint.The results show that after the HIP,the grain size of the V-4Cr-4Ti base metal(BM)obviously increases,while the grain size near the interface is much smaller than that in the V-4Cr-4Ti BM.This is the reason why the hardness near the interface is larger than that of the V-4Cr-4Ti BM.By shear test evaluation,the HIP joint possesses good bonding property with sound strength and ductility.Because there is no phase transformation during HIP,no post-bond heat treatment(PBHT)is necessary for the dissimilar-metal joint.展开更多
Here,we report the leading manu facture of the large-scale integral weldless stainless steel forging ring(φ=15.6 m)by the multilayer additive hot-compression bonding technology.Moreover,the detailed interface healing...Here,we report the leading manu facture of the large-scale integral weldless stainless steel forging ring(φ=15.6 m)by the multilayer additive hot-compression bonding technology.Moreover,the detailed interface healing mecha nism involving interfacial oxide evolution is elucidated,which validates the feasibility and reliability of the technique we proposed.展开更多
基金supported by Natural Science Foundation of Shandong Province(No.ZR2019PEE042)。
文摘Because the bonding interface of dissimilar metal joint between AZ31 B Mg alloy and DP600 galvanized steel by keyholeless friction stir spot welding(KFSSW)is permanent bonding,the interface morphology cannot be directly observed.If the joint is separated by external force,the original features of bonding interface of joint will be destroyed,which has influence on the accuracy for observation and analysis of the result.In this paper,the coordinates of the key point at the interface of every cross-section at intervals of 0.2 mm were measured and connected into an outline.The outline of all interfaces makes up the three-dimensional morphologies of bonding interface between AZ31 B Mg alloy and DP600 steel by KFSSW,which was constructed by Solidworks software to restore the real mechanical bonding state of joint.Combined with the microhardness analysis of cross-section and results of in-situ tensile test,the unique bonding state and morphology of Mg and steel in the welded joint were confirmed.
基金supported by the National Natural Science Foundation of China Key Projects of International Cooperation and Exchanges(No.42020104006)the National Natural Science Foundation of China(No.41630643)+1 种基金the Fundamental Research Funds for the Central Universities(No.CUGCJ1701)the Scientific Research Project of China Three Gorges Corporation LTD.
文摘In rock engineering,the shear strength of the basalt-concrete bonding interface is a key factor affecting the shear performance of hydroelectric dam foundations,embedded rock piles and rock bolts.In this study,30 sets of in-situ direct shear tests were conducted on the basalt-concrete bond interface in the Baihetan dam area to investigate the shear strength characteristics of the basalt-concrete bonding interface.The bonding interface contains two states,i.e.,the bonding interface is not sheared,termed as se(symbolic meaning see Table 1);the bonding interface is sheared with rupture surface,termed as si.The effects of lithology,Joints structure,rock type grade and concrete compressive strength on the shear strength of the concrete-basalt contact surface were investigated.The test results show that the shear strength of the bonding interface(s_(e)&s_(i))of columnar jointed basalt with concrete is greater than that of the bonding interface(s_(e)&s_(i))of non-columnar jointed one with the same rock type grade.When the rock type grade isⅢ_(2),fcol is 1.22 times higher than fncol and ccol is 1.13 times greater than cncol.The shear strength parameters of the basalt-concrete bonding interface differ significantly for different lithologies.The cohesion of the bonding interface(s_(i))of cryptocrystalline basalt with concrete is 2.05 times higher than that of the bonding interface(s_(i))of breccia lava with concrete under the same rock type grade condition.Rock type grade has a large influence on the shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i)).cnol increases by 33%when the grade of rock type rises fromⅢ_(1)toⅡ_(1).the rock type grade has a greater effect on bonding interface(s_(i))cohesion than the coefficient of friction.When the rock type grade is reduced fromⅢ_(2)toⅢ_(1),f_(ncol)′increases by 2%and c_(ncol)′improves by 44%.The shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i))increases with the increase of the compressive strength of concrete.When concrete compressive strength rises from 22.2 to 27.6 MPa,the cohesion increases by 94%.
基金This work was financially supported by the National Natural Science Foundation of China(No.52035005).
文摘Complete understanding of the evolution behaviors of the microstructures and intermetallic compounds(IMCs)along the interface materials flow path in friction stir welding(FSW)of dissimilar Al to Mg alloys is of great significance.In this study,conventional FSW and ultrasonic vibration enhanced FSW(UVeFSW)experiments of Al/Mg alloys were performed,and the instantaneous evolution features of the interface materials around the tool were"frozen"by using the"sudden stop"and simultaneous cooling techniques.The microstructures and IMCs formation at different locations around the exit hole were observed and characterized by scanning electron microscope,energy dispersive spectrometer and transmission elec-tron microscope.It was found that before the materials started to deposit near the back of the tool,“IMC+Mg+IMC+Al”multilayer microstructure and simple IMC layer with(β+γ)sequentially emerged on the Al/Mg interface.With the application of ultrasonic vibration,the multi-layered interface structure only appeared at the middle stage of materials flow around the pin,and ultrasonic vibration just began to play a suppression role on the growth of two sub-layers IMC at a position where the materials deposit.With assistance of ultrasonic vibration in UVeFSW,the tool drove a larger volume of Mg alloy to move toward the retreating side,and the final IMCs thickness was thinner than that in FSW.
基金the support provided by the China Scholarship Council(No.201806290070)the fund by the State Key Laboratory of Solidifi cation Processing in NWPU(No.2019-QZ-01)。
文摘This study focuses on the bonding interface characteristics and mechanical properties of the bobbin tool friction stir welded dissimilar AA6056 and AA2219 aluminum alloy joints using diff erent welding speeds.Voids arise solely in the stir zone at the AA2219 side.A distinct boundary with limited material mixing develops at the middle section of the bonding interface,while excellent material mixing with an irregularly jagged pattern forms at the top and bottom sections of the bonding interface.Increasing the welding speed,the material mixing is rarely changed at the middle section in comparison with the bottom section.Furthermore,a small diff erence between Guinier–Preston dissolution and Q phase precipitation leads to rare change of hardness in the heat aff ected zone(HAZ)at the AA6056 side.The increased hardness of the HAZ at the AA2219 side is attributed to avoidance of the dissolution ofθ’’phase precipitates.A maximum tensile strength of 181 MPa is obtained at 300 mm min-1.Fractures occur at the AA6056 side near the top and bottom surfaces and at the bonding interface in the middle section of the joints.The regions close to the top and bottom surfaces of the joints show a better ductility.
基金supported by the National Natural Science Foundation of China(22175070,22293041,51902081,and 21871106)Key Fund in Hebei Province Department of Education China(ZD2022042)。
文摘Oxygen anion redox reaction provides a high theoretical capacity for Li-rich manganese-based cathodes.However,irreversible surface oxygen release often results in further oxygen loss and exacerbates the decomposition of the electrolyte,which could reduce the capacity contribution from the anionic redox and produce more acidic substances to corrode the surface of the material.In this paper,the surface oxygen release is suppressed by moderating oxygen anion redox activity via constructing chemical bonds between M(M=Fe and La)in LaFeO_(3)and surface oxygen anions of Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2).The constructed interface layer stabilizes the surface lattice oxygen and retards the electrolyte from being attacked by the nucleophilic oxygen generated in the process of oxygen release,as evidenced by Differential Electrochemical Mass Spectrometry(DEMS)and X-ray Photoelectron Spectroscopy(XPS)detections.Moreover,in the charge and discharge process,the formed FeF_(3),located at the cathode electrolyte interfacial layer,is conducive to the stability of the cathode surface.The modified Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2)electrode with 3 wt%LaFeO_(13)exhibits a high specific capacity of 189.5 mA h g-at 1C(200 mA g^(-1))after 150 cycles with capacity retentions of 96.6%,and 112.6 mA h g^(-1)(84.7%)at 5C after 200 cycles higher than the pristine sample.This study provides a rational design chemical bonding method to suppress the oxygen release from the cathode surface and enhance cyclic stability.
基金supported by The Fundamental Research Funds for the Central Universities(No.FRF-TD-12-001)Constructed Project for the Key Laboratory of Beijing(No.FRF-SD-B-378 005B)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120006110019)the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials(No.2012Z-13)
文摘The microstructure, interface thickness, element distribution and interfacial mechanical behavior of Ti-6Al-4V/Al couples prepared by an insert moulding method were investigated in depth in this paper. Moreover, Ti/Al bonding was also given as a comparison for understanding the interface bonding mechanism. It is shown that there is much thinner compact sub-layer for the interface of the Ti-6Al-4V/Al joint, whose morphology is obviously different from that of the Ti/Al joint. The Ti-6Al-4V/Al interface has been proven to contain a slight content of vanadium. Moreover, both the shear strength and the interface reaction rate of Ti-6Al-4V/Al compound materials are lower than those of the Ti/Al ones.
文摘Silicon carbide nanofibers grew on the surface of carbon fibers of a unidirectional carbon preform by CCVD and then chemical vapor infiltration was used to densify the preform to get the SiCNF-C/C composite. The effects of silicon carbide nanofibers on the microstructure of the pyrolytic carbon and the thermal conductivity of the SiCNF-C/C composite were investigated. Results show that silicon carbide nanofibers on the surface of carbon fibers induce the deposition of high texture pyrolytic carbon around them. The interface bonding between carbon fibers and pyrolytic carbon is well adjusted. So the efficiency of heat transfer in the interface of the composite is well enhanced. The thermal conductivity of the SiCNF-C/C composite is greater than that of the C/C composite, especially the thermal conductivity perpendicular to the fiber axis.
基金supported by the National Natural Science Foundation of China(5197219862133007)the Taishan Scholars Program of Shandong Province(tsqn201812002,ts20190908)+1 种基金the Shenzhen Fundamental Research Program(JCYJ20190807093405503)The Natural Science Foundation of Shandong Province(No.ZR2020JQ19)。
文摘Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloying/dealloying processes and low electronic conductivity of Si anodes restrict their electrochemical performance.Thus,carbon(C)materials with special physical and chemical properties are applied in Si anodes to effectively solve these problems.This review focuses on current status in the exploration of Si/C anodes,including the lithiation mechanism and solid electrolyte interface formation,various carbon sources in Si/C anodes,such as traditional carbon sources(graphite,pitch,biomass),and novel carbon sources(MXene,graphene,MOFs-derived carbon,graphdiyne,etc.),as well as interfacial bonding modes of Si and C in the Si/C anodes.Finally,we summarize and prospect the selection of carbonaceous materials,structural design and interface control of Si/C anodes,and application of Si/C anodes in all-solid-state lithium-ion batteries and sodium-ion batteries et al.This review will help researchers in the design of novel Si/C anodes for rechargeable batteries.
基金supported by the National Key Research and Development Program(No.2018YFA0702900)the National Natural Science Foundation of China(No.51975096).
文摘The metallurgical bonding quality of bonding joints is affected by the substrate surface state in hot-compression bonding(HCB),and the surface roughness is a core indicator of the surface state.However,the effects of surface roughness on interface bonding performance(IBP)in the HCB process are unclear for substrates with refractory oxide scales.This study presents the effects of surface roughness on IBP for 316H stainless steel joints fabricated by HCB.A set of HCB parameters for interface bonding critical state of 316H stainless steel joints was determined.The HCB experiments were carried out under parameters of interface bonding critical state to amplify the effect of surface roughness.The interface morphologies,element distribution,and tensile properties were used to characterize the IBP.As a result,the formation mechanisms of the interface pits were revealed and the variation trend of pit number with the roughness was summarized.Finally,the mapping relation between surface roughness and IBP was established.The results show that the degree of rotational dynamic recrystallization becomes weaker with the decrease in the surface roughness and the interface bonding mechanism is completely transformed into discontinuous dynamic recrystallization when the roughness is lower than 0.020μm Sa.The number of interfacial pits decreases as the roughness decreases owing to the weakening of oxide scale aggregation and abrasive inclusion mechanism.The elongation of the tensile specimen cannot increase significantly while the roughness is lower than 0.698μm Sa.
基金the National Natural Science Foundation of China(No.51771150)the National Key Research and Development Program of China(No.2016YFB0701303)+1 种基金the Aeronautical Science Foundation of China(No.201936053001)the Research Fund of the State Key Laboratory of Solidification(NWPU),China(No.2019-TS-07)。
文摘Solid-state diffusion bonding(DB)of TiAl alloy and Ti2 AlNb alloy was carried out using pure Ti as an interlayer at 1000℃under 20 MPa for 60-120 min.The effects of bonding times on the interfacial microstructure and mechanical performance of the TiAl/Ti/Ti_(2)AlNb bonded joints at room temperature(RT)were investigated detailly.The results demonstrated that the diffusion layers(DLs)mainly consisted of four characteristic layers,(Ⅰ)single coarseα_(2)phase adjacent TiAl alloy,(Ⅱ)single refinedα_(2)phase at the bonding interface,(Ⅲ)equiaxed/acicularα_(2)phase embedded inβphase adjacent Ti_(2)AtNb alloy and(IV)both equiaxedα_(2)phase and acicular O phase embedded inβphase adj acent Ti_(2)AlNb alloy,respectively.The thickness of the four layers increased with the increasing of the bonding time.The growth of DLs is controlled by diffusion and the reaction rate constant k for regionⅠ,Ⅱ,ⅢandⅣare 1.22×10^(-6),1.27×10^(-6),2.6×10^(-7)and 7.7×10^(-7)m·s^(-1/2),respectively.Meanwhile,the interfaceα_(2)grain grows up without texture.The maximum tensile strength of 281 MPa was maintained at1000℃for 90 min under the pressure of 20 MPa.Consequently,the phase transformation and dynamic recrystallization behavior of the DLs were discussed.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50974048)the Doctoral Fund of Ministry of Education of China(Grant No.200802140004)+1 种基金the Foundation of Heilongjiang Educational Committee(Grant No.12531116)the Harbin Special Funds for Creative Talents in Science and Technology(Grant No.2013RFQXJ102)
文摘A large number of scraps are produced in the fabrication process of magnesium alloy products. It is necessary to recycle these scraps for the development and scale application of magnesium alloys. In this research,a method for recycling AZ91D magnesium alloy scraps fabricated by hot-press / extrusion was studied. Mechanical properties and microstructure of the recycled specimens were investigated. Microstructural analyses were performed by using the techniques of optical microscopy and scanning electron microscopy. Microstructural observations reveal that the recycled specimens consisted of fine grains when adopting the extrusion temperature of 400- 450 ℃,the extrusion ratio of( 25- 100) ∶ 1 and the extrusion rate of 0. 10- 0. 20 mm / s. Ultimate tensile strength and elongation to failure increased with the increase of the extrusion temperature,the extrusion ratio and the extrusion rate,respectively. Recycled specimens reached the highest ultimate tensile strength of average 361. 47 MPa and the highest elongation to failure of average 11. 55% when adopting the hot-press,the extrusion temperature of 400± 5 ℃,the extrusion ratio of 100 ∶ 1 and the extrusion rate of 0. 15 mm / s. The shape of bonding interface was tightly relation with the ultimate tensile strength. When the bonding interface formed continuous curves,the ultimate tensile strength decreased almost linearly with increasing the average width of the bonding interface. When the bonding interface formed discontinuous curves,the ultimate tensile strength increased almost linearly with the increase the proportion of the fine bonding length accounting for the measured interface length. Ultimate tensile strength of the recycled specimens could be calculated by using the forecastable equation.
基金National Natural Science Foundation of China(Grant No.51875127).
文摘The consolidation Mg-Gd-Y-Zn-Zr billets containing long period-stacking ordered(LPSO)phase were recycled from the metal chips through the spark plasma sintering(SPS)process,which achieves the effective metallurgical bonding between metal chips.The effects of the sintering parameters on the microstructure characteristic and mechanical properties of the recycled billets were studied.The metal chips were effectively bonded in the recycled billets sintered at 500°C,however,the metal chips partly melted into semi-solid state as sintering temperature increased to 550°C.The oxidation films of rare earth(RE)element formed at the bond interface between metal chips during SPS recycling process.The consolidation recycled billets through SPS demonstrated the rival compression failure strain and superior compression stress compared with the referenced cast alloy.The lamellar 14H-LPSO phases hardly precipitate in the vicinity of the bond interface between metal chips after heat treatment with air cooling.However,the furnace cooling facilitates the precipitation of 14H-LPSO phases within the a-Mg grains,even the a-Mg matrix adjacent to the bond interface.The oxide films at the bond interface between the metal chips were zigzagged and fragmented during the isothermal compression.The cracks or holes were hardly observed adjacent to the bond interface during isothermal compression,which reveals superior bond properties and deformation consistency performance between metal chips.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.
基金Fouded by the National Natural Science Foundation of China(No.51175308)the National Science and Technology Major Project of China(No.2012ZX04010032)。
文摘The influences of new,scrap,and five modified Mo fibers on interface bonding strength of fiber-matrix and mechanical strength of RMC were studied.Typical specimens with different fibers and mass ratio of resin and hardener were prepared to verify the above assumptions.Theoretical analysis and experimental results prove that,compared with ordinary new Mo fibers,scrap Mo fibers can perform better in improving interface bonding strength and mechanical properties of RMC because many discharge pits randomly distribute on the surface of scrap fibers.For five modified Mo fibers,interface bonding strength and the reinforcing effect on RMC have been improved obviously.Wherein,comprehensive mechanical properties of RMC are optimal with the addition of M6 fibers which have undergone combined surface treatment including acidification,gas-phase oxidation and coupling treatment.And interface bonding strength between M6 fiber and matrix is the maximum.
基金supported by the National Natural Science Foundation of China(31971743)Forestry Science and Technology Innovation Outstanding Youth Scientific Research Project of Hunan Province,China(XLK201945)+2 种基金Natural Science Foundation of Hunan Province,China(2019JJ40540)Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology,China(2019RS2040)National College Students Innovation and Entrepreneurship Training Program in China(S202010538013).
文摘This study was designed to solve the problem of large waste volume from bamboo processing residues in recent years.Using magnesium oxychloride(MO)cementitious material as the main material and bamboo residue(BR)as the reinforcing material,a BR/MO composite material was prepared.The effects of BR amount on the molding properties,mechanical strength,and water resistance of BR/MO composites were examined and discussed.Scanning electron microscopy(SEM),X-ray diffractometry(XRD),and thermogravimetric analysis were used to characterize composite microscopic morphology,crystalline structure,and heat resistance.The results showed that,when the BR content was 1.00%(by wt),the flowability of MO paste was beneficial to composite molding.Composite mechanical properties and water resistance were greatly affected by BR addition.When the BR content was 1.00%,composite compressive and bending strengths and softening coefficient all reached maximum values.Meanwhile,increases in water absorption by 24 h and decreases of contact angle were small.These results suggested that,when the BR content was 1.00%,composite mechanical properties and water resistance were the best and the mechanical strength also improved with extended composite storage time.SEM analysis indicated that BR played the role of a reinforcing phase in MO matrices.However,when the BR content exceeded 1.00%,interfacial bonding between BR and MO became less.XRD analysis showed that,with 1.00%BR content,composites showed more 5-phase crystals with high strength.This further explained the reason why this composite’s mechanical properties were the best and the heat resistance not deteriorated due to BR,which was easily decomposed.
基金supported by the National Key Research and Development Program of China(2021YFC2101800,2021YFC2400802)the National Natural Science Foundation of China(52173117,21991123)+1 种基金the Ningbo 2025 Science and Technology Major Project(2019B10068)the Science and Technology Commission of Shanghai(20DZ2254900,20DZ2270800)。
文摘Inspired by the multi-layer architecture of mammal skins,interfacial robust,stretchable,and entirely healable gel-elastomer hybrids hold great potential in diverse fields including biomedical devices,wearable electrical devices,and soft robotics.However,existing gel-elastomer hybrids have numerous limitations including low interfacial bonding toughness,complex and time-consuming preparation process,unhealable,and non-reconfiguration.Herein,we propose a simple and general chemical strategy through the interfacial dynamic bonding between gel and elastomer to simultaneously address the abovementioned obstacles.Dynamic covalent bonds readily and repeatably covalent bonding ionogel and elastomer(interfacial toughness:390 J m^(-2)),endowed the hybrids with entire self-healing features like skin and enabled discretionary assembly and reconfiguration.Moreover,this strategy resolved the troublesome contradiction between interfacial stability and reconfiguration.Taking advantage of the aforementioned features,we readily constructed a multi-module,self-healing,self-powered,and realtime monitoring of personal status integrated elastic electronics,which could simply reconfigure the output signal of elastic electronics into an input signal of the devices-braille keyboard.
基金supported by Capacity building project of local universities Science and Technology Commission of Shanghai Municipality(No.19090503500)the National Natural Science Foundation of China(No.51803028)+2 种基金Shanghai Gaofeng&Gaoyuan Project for University Academic Program Development,Collaborative Innovation Center of Fragrance Flavour and Cosmetics,the Fundamental Research Funds for the Central Universities,DHU Distinguished Young Professor Program(No.LZB2021004)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-D-2021020)The authors would like to acknowledge the fellowship from the China Scholarship Council(CSC)under Grant CSC No.202106630044.
文摘Facile and ecofriendly loading of micro/nano function-specific substances to create functional materials is a trend being pursued by researchers.However,current micro/nano particles loading approaches are often hindered by issues such as uneven distribution,unsatisfactory stability and complicate procedure.In this work,we present an aqueous phase reshaping method that only utilizes the moisture to fabricate the"bubble particles",which could perfectly cater to the topography of the substrate.The green preparation of bubble particles adopts an absolutely zero-pollution method,realizing the firm loading of particles on the substrate.Integrating the preparation and loading of particles overcomes the traditional complicate process,while the aqueous phase reshaping ensures uniform and firm loading of the"bubble particles"onto the substrate.Our mechanism demonstrates a significant enhancement in the interface relation after aqueous phase reshaping,with a 121-fold increase in contact surface area achieved by reducing the height by 1μm.Furthermore,we explore for the first time the influence of the nature of the receiving substrate on the interface morphology of particles during electrostatic spraying,which has important guiding significance for the interface relationship of electrostatic spraying and even electrostatic spinning materials.We also screen out the natural antibacterial essential oil linalool as the effective specialized antibacterial agent,which can specifically inhibit the odor-producing Proteus in urine,with an antibacterial rate of up to 100%.Taken together,this simple,ecofriendly method for fabricating functional materials with optimal interface stability appears highly promising for use in various products formed by electrostatic spraying/spinning.
基金financially supported by the National Natural Science Foundation of China (Nos.52174345 and 52064032)the Science and Technology Major Project of Yunnan Province (No.202202AG050004)。
文摘The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength in metal matrix composites. In this study, citric acid was employed as the precursor for synthesizing multiscale carbon nanomaterials(graphene quantum dots and graphene, abbreviated as GQDs and GN). The GQDs@GN/Cu composites were fabricated through a segmented ball milling process in conjunction with subsequent spark plasma sintering(SPS). The intragranular GQDs and intergranular GQDs@GN had synergistically reinforced Cu composites through Orowan strengthening, load transfer strengthening and refinement strengthening. Furthermore,the robust interface bonding between GQDs@GN and Cu effectively mitigated interfacial impedance stemming from electron-boundary scattering. The yield strength and ultimate tensile strength of the GQDs@GN/Cu composites were recorded as 270 and 314 MPa, respectively, representing an improvement of 92 and 28% over pure Cu, while maintaining electrical conductivity at a level comparable to that of pure Cu. This study advances the understanding of the possibility of realizing a synergistic compatibility between electrical conductivity and mechanical strength in Cu composites.
基金the financial support from the National Natural Science Foundation of China(Grant Nos.11872171,91016014,and 51872062)Fundamental Research Funds for the Central Universities(Grant No.B200202117)。
文摘Transition metal carbide/nitride cores within MXenes make them considerably useful for ultra-high-temperature reinforcement.However,extensive research on Ti_(3)C_(2)T_(x) MXene has revealed its tendency to undergo a phase transition to TiCy at temperatures above 800℃due to high activity of a superficial Ti atomic layer.Herein,spark plasma sintering of Ti_(3)C_(2)T_(x) and TiC is performed to prevent the Ti_(3)C_(2)T_(x) phase transition at temperatures up to 1900℃through the fabrication of composites at a pressure of 50 MPa.Using a focused ion beam scanning electron microscope to separate layered substances in the composites and examining selected area diffraction spots in a transmission electron microscope enabled identification of non-phase-transitioned MXene.First-principles calculations based on density functional theory indicated the formation of strong chemical bonding interfaces between Ti_(3)C_(2)T_(x) and TiC,which imposed a stability constraint on the Ti atomic layer at the Ti_(3)C_(2)T_(x) surface.Mechanical performance tests,such as three-point bending and fracture toughness analysis,demonstrated that the addition of Ti_(3)C_(2)T_(x) can effectively improve the cross-scale strengthening and toughening of the TiC matrix,providing a new path for designing and developing two-dimensional(2D)carbides cross-scale-enhanced three-dimensional(3D)carbides with the same elements relying on a wide variety of MXenes.
基金This work was financially supported by the National Key Research and Development Program of China on Magnetic Confinement Nuclear Fusion Energy(Grant No.2018YFE0307101).
文摘Carbide-dispersion strengthened(CDS)vanadium alloy is a kind of advanced structural material for V/Li fusion blanket.The welding technology for the alloy is very important for its application in fusion reactors.In the present study,preliminary investigation on dissimilar-metal bonding by hot isostatic pressing(HIP)was carried out for the CDS V alloy by joining with the conventional V-4Cr-4Ti alloy.Microstructural characterization for the bonding interfaces and mechanical tests for bonding property evaluation were analyzed for the HIP joint.The results show that after the HIP,the grain size of the V-4Cr-4Ti base metal(BM)obviously increases,while the grain size near the interface is much smaller than that in the V-4Cr-4Ti BM.This is the reason why the hardness near the interface is larger than that of the V-4Cr-4Ti BM.By shear test evaluation,the HIP joint possesses good bonding property with sound strength and ductility.Because there is no phase transformation during HIP,no post-bond heat treatment(PBHT)is necessary for the dissimilar-metal joint.
基金supported by the National Key Research and Development Program[Grant No.2018YFA0702900]the National Natural Science Foundation of China[Grant No.51774265]+2 种基金the National Science and Technology Major Project of China[Grant No.2019ZX06004010]Program of CAS Interdisciplinary Innovation TeamYouth Innovation Promotion Association,CAS。
文摘Here,we report the leading manu facture of the large-scale integral weldless stainless steel forging ring(φ=15.6 m)by the multilayer additive hot-compression bonding technology.Moreover,the detailed interface healing mecha nism involving interfacial oxide evolution is elucidated,which validates the feasibility and reliability of the technique we proposed.
