Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electr...Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.展开更多
Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is presen...Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is present.In order to address these challenges,short polymer fibers are randomly dispersed in a cement-based matrix to forma highly ductile engineered cementitious composite(ECC).Thismaterial exhibits high ductility under tensile forces,with its tensile strain being several hundred times greater than conventional concrete.Since concrete is inherently weak in tension,the tensile strain capacity(TSC)has become one of the most extensively researched properties.As a result,developing a model to predict the TSC of the ECC and to optimize the mixture proportions becomes challenging.Meanwhile,the effort required for laboratory trial batches to determine the TSC is reduced.To achieve the research objectives,five distinct models,artificial neural network(ANN),nonlinear model(NLR),linear relationship model(LR),multi-logistic model(MLR),and M5P-tree model(M5P),are investigated and employed to predict the TSCof ECCmixtures containing fly ash.Data from115 mixtures are gathered and analyzed to develop a new model.The input variables include mixture proportions,fiber length and diameter,and the time required for curing the various mixtures.The model’s effectiveness is evaluated and verified based on statistical parameters such as R2,mean absolute error(MAE),scatter index(SI),root mean squared error(RMSE),and objective function(OBJ)value.Consequently,the ANN model outperforms the others in predicting the TSC of the ECC,with RMSE,MAE,OBJ,SI,and R2 values of 0.42%,0.3%,0.33%,0.135%,and 0.98,respectively.展开更多
The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carrie...The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carried out at room temperature at the strain rate of 4.17 × 10<sup>-3</sup> s<sup>-1</sup>, 20.85 × 10<sup>-3</sup> s<sup>-1</sup>, and 208.5 × 10<sup>-3</sup> s<sup>-1</sup>. It is seen that the tensile strength increases and the ductility decrease with increasing the strain rate over the investigated range. From the strain rate change test results, the strain sensitivity values are found in the range of 0.0831 to 0.1455 due to the addition of different alloying elements.展开更多
Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the (100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperature...Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the (100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperatures and strain rates. The temperature and strain rate dependences of tensile properties were investigated. The simulation results show that the elastic modulus and the yield strength are gradually decreasing with the increase of temperature, while with the increase of the strain rate, the stress--strain curves fluctuate more intensely and the ultrathin nickel nanowires rupture at one smaller and smaller strain. At an ideal temperature of 0.01 K, the yield strength of the nanowires drops rapidly with the increase of strain rate, and at other temperatures the strain rate has a little influence on the elastic modulus and the yield strength. Finally, the effects of size on the tensile properties of ultrathin nickel nanowires were briefly discussed.展开更多
Tensile mechanical properties of 1.6Si-1.58Mn-0.195C TRIP (transformation-induced plasticity) steels under high strain rate and effects of DP (dual-phase) treatments were studied and compared to the quasi-static tensi...Tensile mechanical properties of 1.6Si-1.58Mn-0.195C TRIP (transformation-induced plasticity) steels under high strain rate and effects of DP (dual-phase) treatments were studied and compared to the quasi-static tensile behavior. The results show that the increasing of strain rate leads to increasing in their strengths and decreasing in the uniform elongation remarkably. Because the stable retained austenite in TRIP steel can transform to martensite during tensile testing and the material exhibits excellent characteristic of transformation induced plasticity, the plastic deformation behavior is evidently improved and the combination of strength and elongation is superior to that of dual-phase steel, although its strength is smaller than that of DP steel. However, DP treated steel shown lower elongation under dynamic tension in spite of higher strength. A model was proposed to explain the excellent elongation rate of TRIP steel compared with DP steel on the basis of SEM analysis and the strength of the components in microstructure.展开更多
A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect...A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect.Moreover,the most important is that very low polarization dependence of gain (<0 7dB),fiber to fiber lossless operation current (70~90mA) and a high extinction ratio (>50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520~1609nm) which nearly covers the spectral region of the whole C band (1525~1565nm) and the whole L band (1570~1610nm).The gating time is also improved by decreasing carrier lifetime.The wide band polarization insensitive SOA gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.展开更多
The design of efficient Ru-based electrocatalysts with high intrinsic activities for acidic water oxidation is highly desirable and challenging for water splitting in proton exchange membrane electrolyzers.Here,for th...The design of efficient Ru-based electrocatalysts with high intrinsic activities for acidic water oxidation is highly desirable and challenging for water splitting in proton exchange membrane electrolyzers.Here,for the first time,we engineer the charge density of Ru(IV)by creating tensile strains in the RuO2 shell of Ru@RuO2 core-shell nanoparticles,viz.Ru@RuO2-L.High-resolution spectroscopic characterizations confirm the presence of av.6%tensile strain in Ru-O bonds,which results in an effective reduction of the Ru(IV)charge density.The resultant Ru^X+(4<X<5)active sites greatly accelerate the oxygen evolution reaction(OER)in an acidic electrolyte,leading to a remarkably low overpotential of 191 mV at 10 mA cm^-2.These values are lower than those for the benchmark RuO2 catalyst and are also among the lowest for efficient Ru-based electrocatalysts reported thus far.The specific activity and mass activity are also greatly enhanced 4.2-fold and 17.7-fold compared to those of RuO2,respectively.The acidic OER activity improvement is ascribed to the lowered adsorption energy of*OOH,owing to the reduced charge density of Ru(IV),and the rapid charge transport owing to the Ru core.Ru@RuO2-L also demonstrates high feasibility as the anode catalyst for the overall water splitting in acidic media.展开更多
The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive...The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive to the strain rate at room temperature but significantly sensitive to the strain rate at high temperature. An increase of the strain rate or a decrease of the temperature results in an obvious change of fracture mode. It is found that the strain rate sensitivity of this alloy varying with temperature is due to the dislocation climb generated at high temperature.展开更多
A self designed Split Hopkinson tensile bar setup with a rotating disk was used to investigate room temperature tensile properties of a γ TiAl alloy in duplex (DP) and fully lamellar (FL) microstructural forms under ...A self designed Split Hopkinson tensile bar setup with a rotating disk was used to investigate room temperature tensile properties of a γ TiAl alloy in duplex (DP) and fully lamellar (FL) microstructural forms under the dynamic strain rates between 70 and 800 s -1 . It was found that for both forms the alloy is brittle at these strain rates, exhibiting near zero ductility. The σ b at dynamic strain rate is greater than that at the static strain rate of 5×10 -1 s -1 , and the σ b of the DP material is higher than that of the FL material. Fractography analysis indicated that both materials at dynamic strain rates fracture in a mixed mode of predominant transgranular cleavage and minor intergranular cracking, which is similar to that at the static strain rate. The room temperature brittleness of the alloy is not environmentally related. : A self designed Split Hopkinson tensile bar setup with a rotating disk was used to investigate room temperature tensile properties of a γ TiAl alloy in duplex (DP) and fully lamellar (FL) microstructural forms under the dynamic strain rates between 70 and 800 s -1 . It was found that for both forms the alloy is brittle at these strain rates, exhibiting near zero ductility. The σ b at dynamic strain rate is greater than that at the static strain rate of 5×10 -1 s -1 , and the σ b of the DP material is higher than that of the FL material. Fractography analysis indicated that both materials at dynamic strain rates fracture in a mixed mode of predominant transgranular cleavage and minor intergranular cracking, which is similar to that at the static strain rate. The room temperature brittleness of the alloy is not environmentally related.展开更多
The quasi-static and dynamic tensile tests of aramid and high strength PVA fiber bundles are carried out under a wider range of strain rate by use of MTS (Materials Testing System) and bar-bar tensile impact apparatus...The quasi-static and dynamic tensile tests of aramid and high strength PVA fiber bundles are carried out under a wider range of strain rate by use of MTS (Materials Testing System) and bar-bar tensile impact apparatus. The influences of strain rate on mechanical properties of aramid and high strength polyvinyl alcohol fibers are studied. Micro failure mechanisms of fibers at different strain rates are examined by means of SEM.展开更多
Tensile properties of a two phase γ Ti 47Al 1.5Cr 0.5Mn 2.8Nb alloy with a duplex microstructure were tested under strain rates ranging from 5×10 -5 to 5×10 -3 s -1 at temperatures from 1 123 K to 1 273 K. ...Tensile properties of a two phase γ Ti 47Al 1.5Cr 0.5Mn 2.8Nb alloy with a duplex microstructure were tested under strain rates ranging from 5×10 -5 to 5×10 -3 s -1 at temperatures from 1 123 K to 1 273 K. It was found that there exists approximately linear relationship between the flow stresses and the logarithm of the strain rate at different temperatures. The strain rate dependence was analyzed by thermal activation theory, and dislocation climbing has been identified as the rate controlling mechanism.展开更多
The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direct...The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.展开更多
The effects of Al-8B grain refiner on microstructure and tensile properties of an Al-12Zn-3Mg-2.5Cu alloy produced by modified strain induced melt activation process were investigated. Pre-deformation of 60% was used ...The effects of Al-8B grain refiner on microstructure and tensile properties of an Al-12Zn-3Mg-2.5Cu alloy produced by modified strain induced melt activation process were investigated. Pre-deformation of 60% was used by hot working at 300 ℃. After pre-deformation, the samples were heated to a temperature above the solidus and below the liquidus point and maintained in the isothermal conditions at three different temperatures(500, 550 and 590 ℃) for varying time(10, 20 and 40 min). It was observed that strain induced melt activation has caused the globular morphology of α(Al) grains. Microstructural study was carried out on the alloy by using optical microscope and scanning electron microscope in both unrefined and B-refined conditions. The results showed that for the desired microstructures of the alloy during SIMA process, the optimum temperature and time are 550 ℃ and 10 min, respectively. After the T6 heat treatment, the average tensile strengths increased from 278 to 585 MPa and 252 to 560 MPa for samples refined with 3.75% Al-8B before and after SIMA process, respectively. The ultimate strength of SIMA specimens is lower than that of B-refined specimens.展开更多
This work investigates the feasibility of utilizing reactive recycled powder(RP)from construction and demolition(C&D)waste as supplementary cementitious material(SCM)to achieve a ductile strain hardening cementiti...This work investigates the feasibility of utilizing reactive recycled powder(RP)from construction and demolition(C&D)waste as supplementary cementitious material(SCM)to achieve a ductile strain hardening cementitious composites(SHCC).The recycled mortar powder(RMP)from mortar waste,recycled concrete powder(RCP)from concrete waste and recycled brick powder(RBP)from clay brick waste were first prepared,and the micro-properties and tensile behavior of SHCC containing various types and replacement ratios of RPs were determined.The incorporated RP promotes pozzolanic and filler effects,while the hydration products in cementitious materials decrease with RP incorporation;therefore,the incorporated RP decreases the compressive strength of SHCC.Attributed to the reduction in the matrix strength,the incorporated RP increases the crack-bridging extent and ductility of SHCC;the irregular micro-structure and high reactivity of RP also help the strain-hardening performance of the prepared SHCC.In addition,the strainhardening performance of SHCC containing RMP and RBP is surperior to that of SHCC with RCP and is slightly lower than that of SHCC with fly ash(FA);for instance,the ultimate strain of SHCC containing 54%FA,RMP,RCP and RBP is 3.67%,3.61%,2.52%and 3.53%,respectively.In addition,the strain-hardening behavior of an SHCC doubled mix with FA and RMP or RBP has a similar ultimate strain and a higher ultimate stress than SHCC containing only FA.展开更多
The effects of biaxial tensile pre-strain on the forming limit of DP590 high-strength steel under high strain rate were investigated. The stress-strain curves of DP590 steel sheet under the biaxial tensile of differen...The effects of biaxial tensile pre-strain on the forming limit of DP590 high-strength steel under high strain rate were investigated. The stress-strain curves of DP590 steel sheet under the biaxial tensile of different load ratios were obtained. The forming limit diagrams(FLDs) of DP590 steel sheet under biaxial tensile pre-strain and electromagnetic hybrid forming were established. Results showed that the biaxial tensile pre-strain had significant effects on the formability of DP590 steel. The pre-strain in a certain range improved the forming limit of DP590 steel under high rate, and the forming limit increased with the pre-strain. The prestrain in the same direction of high rate increased the forming limit of the final deformation under complex strain paths conditions, but the pre-strain in the vertical direction decreased the minor strain under the high strain rate.展开更多
The oxygen evolution reaction(OER)is a crucial step in metal-air batteries and water splitting technologies,playing a significant role in the efficiency and achievable heights of these two technologies.However,the OER...The oxygen evolution reaction(OER)is a crucial step in metal-air batteries and water splitting technologies,playing a significant role in the efficiency and achievable heights of these two technologies.However,the OER is a four-step,four-electron reaction,and its slow kinetics result in high overpotentials,posing a challenge.To address this issue,numerous strategies involving modified catalysts have been proposed and proven to be highly efficient.In these strategies,the introduction of strain has been widely reported because it is generally believed to effectively regulate the electronic structure of metal sites and alter the adsorption energy of catalyst surfaces with reaction intermediates.However,strain has many other effects that are not well known,making it an important yet unexplored area.Based on this,this review provides a detailed introduction to the various roles of strain in OER.To better explain these roles,the review also presents the definition of strain and elucidates the potential mechanisms of strain in OER based on the d-band center theory and adsorption volcano plot.Additionally,the review showcases various ways of introducing strain in OER through examples reported in the latest literature,aiming to provide a comprehensive perspective for the development of strain engineering.Finally,the review analyzes the appropriate proportion of strain introduction,compares compressive and tensile strain,and examines the impact of strain on stability.And the review offers prospects for future research directions in this emerging field.展开更多
The first-order Raman spectroscopy of diamond exhibits splitting and redshift after the burst of high-pressure(160–200 GPa) and high-temperature(~2000 K). The observed longitudinal optical(LO) and the transverse opt...The first-order Raman spectroscopy of diamond exhibits splitting and redshift after the burst of high-pressure(160–200 GPa) and high-temperature(~2000 K). The observed longitudinal optical(LO) and the transverse optical(TO) splitting of Raman phonon is related to the tensile-strain induced activation of the forbidden or silent Raman modes that arise in the proximity of the Brillouin zone center.展开更多
Tensile-strained Ge/SiGe multiple quantum wells (MQWs) were grown on a Ge-on-Si virtual substrate using ultrahigh vacuum chemical vapor deposition on an n+-Si (001) substrate. Direct-bandgap electroluminescence f...Tensile-strained Ge/SiGe multiple quantum wells (MQWs) were grown on a Ge-on-Si virtual substrate using ultrahigh vacuum chemical vapor deposition on an n+-Si (001) substrate. Direct-bandgap electroluminescence from the MQWs light emitting diode was observed at room temperature. The quantum confinement effect of the direct-bandgap transitions is in good agreement with the theoretical calculated results. The redshift mechanism of emission wavelength related to the thermal effect is discussed,展开更多
The hole subband structures and effective masses of tensile strained Si/Sil-yGey quantum wells are calculated by using the 6 × 6 k·p method. The results show that when the tensile strain is induced in the qu...The hole subband structures and effective masses of tensile strained Si/Sil-yGey quantum wells are calculated by using the 6 × 6 k·p method. The results show that when the tensile strain is induced in the quantum well, the light-hole state becomes the ground state, and the light hole effective masses in the growth direction are strongly reduced while the in-plane effective masses are considerable. Quantitative calculation of the valence intersubband transition between two light hole states in a 7nm tensile strained Si/Si0.55Ge0.45 quantum well grown on a relaxed Si0.5Ge0.5 (100) substrates shows a large absorption coefficient of 8400 cm^-1.展开更多
After constructing a stress and strain model, the valence bands of in-plane biaxial tensile strained Si is calculated by k·p method. In the paper we calculate the accurate anisotropy valance bands and the splitti...After constructing a stress and strain model, the valence bands of in-plane biaxial tensile strained Si is calculated by k·p method. In the paper we calculate the accurate anisotropy valance bands and the splitting energy between light and heavy hole bands. The results show that the valance bands are highly distorted, and the anisotropy is more obvious. To obtain the density of states (DOS) effective mass, which is a very important parameter for device modeling, a DOS effective mass model of biaxial tensile strained Si is constructed based on the valance band calculation. This model can be directly used in the device model of metal-oxide semiconductor field effect transistor (MOSFET). It also a provides valuable reference for biaxial tensile strained silicon MOSFET design.展开更多
基金supported by the National Natural Science Foundation of China(21872040,22162004)the Excellent Scholars and Innovation Team of Guangxi Universities,the Innovation Project of Guangxi Graduate Education(YCBZ2022038)the High-performance Computing Platform of Guangxi University.
文摘Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.
文摘Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is present.In order to address these challenges,short polymer fibers are randomly dispersed in a cement-based matrix to forma highly ductile engineered cementitious composite(ECC).Thismaterial exhibits high ductility under tensile forces,with its tensile strain being several hundred times greater than conventional concrete.Since concrete is inherently weak in tension,the tensile strain capacity(TSC)has become one of the most extensively researched properties.As a result,developing a model to predict the TSC of the ECC and to optimize the mixture proportions becomes challenging.Meanwhile,the effort required for laboratory trial batches to determine the TSC is reduced.To achieve the research objectives,five distinct models,artificial neural network(ANN),nonlinear model(NLR),linear relationship model(LR),multi-logistic model(MLR),and M5P-tree model(M5P),are investigated and employed to predict the TSCof ECCmixtures containing fly ash.Data from115 mixtures are gathered and analyzed to develop a new model.The input variables include mixture proportions,fiber length and diameter,and the time required for curing the various mixtures.The model’s effectiveness is evaluated and verified based on statistical parameters such as R2,mean absolute error(MAE),scatter index(SI),root mean squared error(RMSE),and objective function(OBJ)value.Consequently,the ANN model outperforms the others in predicting the TSC of the ECC,with RMSE,MAE,OBJ,SI,and R2 values of 0.42%,0.3%,0.33%,0.135%,and 0.98,respectively.
文摘The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carried out at room temperature at the strain rate of 4.17 × 10<sup>-3</sup> s<sup>-1</sup>, 20.85 × 10<sup>-3</sup> s<sup>-1</sup>, and 208.5 × 10<sup>-3</sup> s<sup>-1</sup>. It is seen that the tensile strength increases and the ductility decrease with increasing the strain rate over the investigated range. From the strain rate change test results, the strain sensitivity values are found in the range of 0.0831 to 0.1455 due to the addition of different alloying elements.
基金Project(51205302)supported by the National Natural Science Foundation of ChinaProject(2013JM7017)supported by the Natural Science Basic Research Plan in Shanxi Province of ChinaProject(K5051304006)supported by the Fundamental Research Funds for the Central Universities,China
文摘Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the (100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperatures and strain rates. The temperature and strain rate dependences of tensile properties were investigated. The simulation results show that the elastic modulus and the yield strength are gradually decreasing with the increase of temperature, while with the increase of the strain rate, the stress--strain curves fluctuate more intensely and the ultrathin nickel nanowires rupture at one smaller and smaller strain. At an ideal temperature of 0.01 K, the yield strength of the nanowires drops rapidly with the increase of strain rate, and at other temperatures the strain rate has a little influence on the elastic modulus and the yield strength. Finally, the effects of size on the tensile properties of ultrathin nickel nanowires were briefly discussed.
基金the financial supports of Shanghai Development Foun-dation of Auto Industry and the National Natural Science Foundation of China (No. 50171038).
文摘Tensile mechanical properties of 1.6Si-1.58Mn-0.195C TRIP (transformation-induced plasticity) steels under high strain rate and effects of DP (dual-phase) treatments were studied and compared to the quasi-static tensile behavior. The results show that the increasing of strain rate leads to increasing in their strengths and decreasing in the uniform elongation remarkably. Because the stable retained austenite in TRIP steel can transform to martensite during tensile testing and the material exhibits excellent characteristic of transformation induced plasticity, the plastic deformation behavior is evidently improved and the combination of strength and elongation is superior to that of dual-phase steel, although its strength is smaller than that of DP steel. However, DP treated steel shown lower elongation under dynamic tension in spite of higher strength. A model was proposed to explain the excellent elongation rate of TRIP steel compared with DP steel on the basis of SEM analysis and the strength of the components in microstructure.
文摘A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect.Moreover,the most important is that very low polarization dependence of gain (<0 7dB),fiber to fiber lossless operation current (70~90mA) and a high extinction ratio (>50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520~1609nm) which nearly covers the spectral region of the whole C band (1525~1565nm) and the whole L band (1570~1610nm).The gating time is also improved by decreasing carrier lifetime.The wide band polarization insensitive SOA gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.
文摘The design of efficient Ru-based electrocatalysts with high intrinsic activities for acidic water oxidation is highly desirable and challenging for water splitting in proton exchange membrane electrolyzers.Here,for the first time,we engineer the charge density of Ru(IV)by creating tensile strains in the RuO2 shell of Ru@RuO2 core-shell nanoparticles,viz.Ru@RuO2-L.High-resolution spectroscopic characterizations confirm the presence of av.6%tensile strain in Ru-O bonds,which results in an effective reduction of the Ru(IV)charge density.The resultant Ru^X+(4<X<5)active sites greatly accelerate the oxygen evolution reaction(OER)in an acidic electrolyte,leading to a remarkably low overpotential of 191 mV at 10 mA cm^-2.These values are lower than those for the benchmark RuO2 catalyst and are also among the lowest for efficient Ru-based electrocatalysts reported thus far.The specific activity and mass activity are also greatly enhanced 4.2-fold and 17.7-fold compared to those of RuO2,respectively.The acidic OER activity improvement is ascribed to the lowered adsorption energy of*OOH,owing to the reduced charge density of Ru(IV),and the rapid charge transport owing to the Ru core.Ru@RuO2-L also demonstrates high feasibility as the anode catalyst for the overall water splitting in acidic media.
基金This work was financially supported by the National Natural Science Foundation of China (No.50274005) and the State Key Projectfor Fundamental Research Developing Plan (No.G2000067206-2).
文摘The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive to the strain rate at room temperature but significantly sensitive to the strain rate at high temperature. An increase of the strain rate or a decrease of the temperature results in an obvious change of fracture mode. It is found that the strain rate sensitivity of this alloy varying with temperature is due to the dislocation climb generated at high temperature.
文摘A self designed Split Hopkinson tensile bar setup with a rotating disk was used to investigate room temperature tensile properties of a γ TiAl alloy in duplex (DP) and fully lamellar (FL) microstructural forms under the dynamic strain rates between 70 and 800 s -1 . It was found that for both forms the alloy is brittle at these strain rates, exhibiting near zero ductility. The σ b at dynamic strain rate is greater than that at the static strain rate of 5×10 -1 s -1 , and the σ b of the DP material is higher than that of the FL material. Fractography analysis indicated that both materials at dynamic strain rates fracture in a mixed mode of predominant transgranular cleavage and minor intergranular cracking, which is similar to that at the static strain rate. The room temperature brittleness of the alloy is not environmentally related. : A self designed Split Hopkinson tensile bar setup with a rotating disk was used to investigate room temperature tensile properties of a γ TiAl alloy in duplex (DP) and fully lamellar (FL) microstructural forms under the dynamic strain rates between 70 and 800 s -1 . It was found that for both forms the alloy is brittle at these strain rates, exhibiting near zero ductility. The σ b at dynamic strain rate is greater than that at the static strain rate of 5×10 -1 s -1 , and the σ b of the DP material is higher than that of the FL material. Fractography analysis indicated that both materials at dynamic strain rates fracture in a mixed mode of predominant transgranular cleavage and minor intergranular cracking, which is similar to that at the static strain rate. The room temperature brittleness of the alloy is not environmentally related.
文摘The quasi-static and dynamic tensile tests of aramid and high strength PVA fiber bundles are carried out under a wider range of strain rate by use of MTS (Materials Testing System) and bar-bar tensile impact apparatus. The influences of strain rate on mechanical properties of aramid and high strength polyvinyl alcohol fibers are studied. Micro failure mechanisms of fibers at different strain rates are examined by means of SEM.
文摘Tensile properties of a two phase γ Ti 47Al 1.5Cr 0.5Mn 2.8Nb alloy with a duplex microstructure were tested under strain rates ranging from 5×10 -5 to 5×10 -3 s -1 at temperatures from 1 123 K to 1 273 K. It was found that there exists approximately linear relationship between the flow stresses and the logarithm of the strain rate at different temperatures. The strain rate dependence was analyzed by thermal activation theory, and dislocation climbing has been identified as the rate controlling mechanism.
基金National Natural Science Foundations of China(Nos.11272087,11572085)Financial Supports from Foundation for the Fok Ying-Tong Education Foundation of China(No.141070)the Fundamental Research Funds for the Central Universities of China(No.170310103)
文摘The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.
文摘The effects of Al-8B grain refiner on microstructure and tensile properties of an Al-12Zn-3Mg-2.5Cu alloy produced by modified strain induced melt activation process were investigated. Pre-deformation of 60% was used by hot working at 300 ℃. After pre-deformation, the samples were heated to a temperature above the solidus and below the liquidus point and maintained in the isothermal conditions at three different temperatures(500, 550 and 590 ℃) for varying time(10, 20 and 40 min). It was observed that strain induced melt activation has caused the globular morphology of α(Al) grains. Microstructural study was carried out on the alloy by using optical microscope and scanning electron microscope in both unrefined and B-refined conditions. The results showed that for the desired microstructures of the alloy during SIMA process, the optimum temperature and time are 550 ℃ and 10 min, respectively. After the T6 heat treatment, the average tensile strengths increased from 278 to 585 MPa and 252 to 560 MPa for samples refined with 3.75% Al-8B before and after SIMA process, respectively. The ultimate strength of SIMA specimens is lower than that of B-refined specimens.
基金The authors gratefully acknowledge the project funded by Key R&D Program of China 2018YFD1101002National Natural Science Foundation of China(51778309).
文摘This work investigates the feasibility of utilizing reactive recycled powder(RP)from construction and demolition(C&D)waste as supplementary cementitious material(SCM)to achieve a ductile strain hardening cementitious composites(SHCC).The recycled mortar powder(RMP)from mortar waste,recycled concrete powder(RCP)from concrete waste and recycled brick powder(RBP)from clay brick waste were first prepared,and the micro-properties and tensile behavior of SHCC containing various types and replacement ratios of RPs were determined.The incorporated RP promotes pozzolanic and filler effects,while the hydration products in cementitious materials decrease with RP incorporation;therefore,the incorporated RP decreases the compressive strength of SHCC.Attributed to the reduction in the matrix strength,the incorporated RP increases the crack-bridging extent and ductility of SHCC;the irregular micro-structure and high reactivity of RP also help the strain-hardening performance of the prepared SHCC.In addition,the strainhardening performance of SHCC containing RMP and RBP is surperior to that of SHCC with RCP and is slightly lower than that of SHCC with fly ash(FA);for instance,the ultimate strain of SHCC containing 54%FA,RMP,RCP and RBP is 3.67%,3.61%,2.52%and 3.53%,respectively.In addition,the strain-hardening behavior of an SHCC doubled mix with FA and RMP or RBP has a similar ultimate strain and a higher ultimate stress than SHCC containing only FA.
基金Funded by the National Natural Science Foundation of China(Nos.51205298 and 51475345)the China Postdoctoral Science Foundation(No.2014M552096)the Open Fund Project of State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(No.P2015-01)
文摘The effects of biaxial tensile pre-strain on the forming limit of DP590 high-strength steel under high strain rate were investigated. The stress-strain curves of DP590 steel sheet under the biaxial tensile of different load ratios were obtained. The forming limit diagrams(FLDs) of DP590 steel sheet under biaxial tensile pre-strain and electromagnetic hybrid forming were established. Results showed that the biaxial tensile pre-strain had significant effects on the formability of DP590 steel. The pre-strain in a certain range improved the forming limit of DP590 steel under high rate, and the forming limit increased with the pre-strain. The prestrain in the same direction of high rate increased the forming limit of the final deformation under complex strain paths conditions, but the pre-strain in the vertical direction decreased the minor strain under the high strain rate.
基金financially supported by the National Natural Science Foundation of China(52071072)the Fundamental Research Funds for the Central Universities(2023GFZD03)+4 种基金the Natural Science Foundation-Steel,the Iron Foundation of Hebei Province(E2022501030)the Key Research and Development Plan of Qinhuangdao City(202302B013)the Liaoning Applied Basic Research Program(2023JH2/101300011)the Basic scientific research project of Liaoning Province Department of Education(LJKZZ20220024)the Shenyang Science and Technology Project(23-407-3-13)。
文摘The oxygen evolution reaction(OER)is a crucial step in metal-air batteries and water splitting technologies,playing a significant role in the efficiency and achievable heights of these two technologies.However,the OER is a four-step,four-electron reaction,and its slow kinetics result in high overpotentials,posing a challenge.To address this issue,numerous strategies involving modified catalysts have been proposed and proven to be highly efficient.In these strategies,the introduction of strain has been widely reported because it is generally believed to effectively regulate the electronic structure of metal sites and alter the adsorption energy of catalyst surfaces with reaction intermediates.However,strain has many other effects that are not well known,making it an important yet unexplored area.Based on this,this review provides a detailed introduction to the various roles of strain in OER.To better explain these roles,the review also presents the definition of strain and elucidates the potential mechanisms of strain in OER based on the d-band center theory and adsorption volcano plot.Additionally,the review showcases various ways of introducing strain in OER through examples reported in the latest literature,aiming to provide a comprehensive perspective for the development of strain engineering.Finally,the review analyzes the appropriate proportion of strain introduction,compares compressive and tensile strain,and examines the impact of strain on stability.And the review offers prospects for future research directions in this emerging field.
基金Project supported by the National Natural Science Foundation of China(Grant No.11774247)
文摘The first-order Raman spectroscopy of diamond exhibits splitting and redshift after the burst of high-pressure(160–200 GPa) and high-temperature(~2000 K). The observed longitudinal optical(LO) and the transverse optical(TO) splitting of Raman phonon is related to the tensile-strain induced activation of the forbidden or silent Raman modes that arise in the proximity of the Brillouin zone center.
基金supported by the National Basic Research Program of China(Grant No.2013CB632103)the National Natural Science Foundation of China(Grant Nos.61036003,61176013,and 61177038)the High Technology Research and Development Program of China(Grant No.2011AA010302)
文摘Tensile-strained Ge/SiGe multiple quantum wells (MQWs) were grown on a Ge-on-Si virtual substrate using ultrahigh vacuum chemical vapor deposition on an n+-Si (001) substrate. Direct-bandgap electroluminescence from the MQWs light emitting diode was observed at room temperature. The quantum confinement effect of the direct-bandgap transitions is in good agreement with the theoretical calculated results. The redshift mechanism of emission wavelength related to the thermal effect is discussed,
基金supported by National Natural Science Foundation of China (Grant Nos 50672079,60336010 and 60676027)National Basic Research Program of China (Grant No 2007CB613400)
文摘The hole subband structures and effective masses of tensile strained Si/Sil-yGey quantum wells are calculated by using the 6 × 6 k·p method. The results show that when the tensile strain is induced in the quantum well, the light-hole state becomes the ground state, and the light hole effective masses in the growth direction are strongly reduced while the in-plane effective masses are considerable. Quantitative calculation of the valence intersubband transition between two light hole states in a 7nm tensile strained Si/Si0.55Ge0.45 quantum well grown on a relaxed Si0.5Ge0.5 (100) substrates shows a large absorption coefficient of 8400 cm^-1.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60976068 and 60936005)the Cultivation Fund of the Key Scientific and Technical Innovation Project,Ministry of Education of China (Grant No. 78083)
文摘After constructing a stress and strain model, the valence bands of in-plane biaxial tensile strained Si is calculated by k·p method. In the paper we calculate the accurate anisotropy valance bands and the splitting energy between light and heavy hole bands. The results show that the valance bands are highly distorted, and the anisotropy is more obvious. To obtain the density of states (DOS) effective mass, which is a very important parameter for device modeling, a DOS effective mass model of biaxial tensile strained Si is constructed based on the valance band calculation. This model can be directly used in the device model of metal-oxide semiconductor field effect transistor (MOSFET). It also a provides valuable reference for biaxial tensile strained silicon MOSFET design.