Recrystallization behavior of a low carbon X70 pipeline steel was studied in the plane strain compression condition. It was found that the dynamic recovery but no dynamic recrystal- lization occurred in the current ex...Recrystallization behavior of a low carbon X70 pipeline steel was studied in the plane strain compression condition. It was found that the dynamic recovery but no dynamic recrystal- lization occurred in the current experimental condition. A method for examining the prior austenite grain boundary corrosion was supposed.展开更多
The development of efficient and durable electrocatalysts for oxygen reduction reaction(ORR)holds a pivotal significance in the successful commercialization of proton exchange membrane fuel cells(PEMFCs)but is still c...The development of efficient and durable electrocatalysts for oxygen reduction reaction(ORR)holds a pivotal significance in the successful commercialization of proton exchange membrane fuel cells(PEMFCs)but is still challenging.Herein,we report a worm-liked PtCu nanocrystals dispersed on nitrogen-doped carbon hollow microspheres(Pt_(0.38)Cu_(0.62)/N-HCS).Benefiting from its structural and compositional advantages,the resulting Pt_(0.38)Cu_(0.62)/N-HCS catalyst delivers exceptional electrocatalytic activity for ORR,with a half-wave potential(E_(1/2))of 0.837 V,a mass activity of 0.672 A mgPt^(-1),and a Tafel slope of 50.66 mV dec^(-1),surpassing that of commercial Pt/C.Moreover,the Pt_(0.38)Cu_(0.62)/N-HCS follows the desired four-electron transfer mechanism throughout the ORR process,thereby displaying a high selectivity for direct reduction of O_(2)to H_(2)O.Remarkably,this catalyst also showcases high stability,with only a 25 mV drop in E_(1/2)after 10,000 cycles in an acidic electrolyte.Theoretical calculations elucidate the incorporation of Cu into Pt lattice induces compressive strain,which effectively tailors the d band center of Pt active sites and strengthens the surface chemisorption of O_(2)molecules on PtCu alloys.Consequently,the Pt_(0.38)Cu_(0.62)/N-HCS catalyst exhibits an improved ability to adsorb O_(2)molecules on its surface,accelerating the reaction kinetics of O_(2)conversion to*OOH.Additionally,Cu atoms,not only serving as sacrificial anode,undergo preferential oxidation during PEMFCs operation when compared to Pt,but also the stable Cu species in PtCu alloys contributes significantly to maintaining the strain effect,collectively enhancing both activity and durability.Overall,this research offers an effective and promising approach to enhance the activity and stability of Pt-based ORR electrocatalysts in PEMFCs.展开更多
Strain effects have garnered significant attention in catalytic applications due to their ability to modulate the electronic structure and surface adsorption properties of catalysts.In this study,we propose a novel ap...Strain effects have garnered significant attention in catalytic applications due to their ability to modulate the electronic structure and surface adsorption properties of catalysts.In this study,we propose a novel approach called“similar stacking”for stress modulation,achieved through the loading of Co_(2)P on Ni_(2)P(Ni_(2)P/Co_(2)P).Theoretical simulations reveal that the compressive strain induced by Co_(2)P influences orbital overlap and electron transfer with hydrogen atoms.Furthermore,the number of stacked layers can be adjusted by varying the precursor soaking time,which further modulates the strain range and hydrogen adsorption.Under a 2-h soaking condition,the strain effect proves favorable for efficient hydrogen production.Experimental characterizations using X-ray diffraction,high-angel annular dark-field scanning transmission election microscope(HAADF-STEM),and X-ray absorption near-edge structure spectroscopy successfully demonstrate lattice contraction of Co_(2)P and bond length shortening of Co-P.Remarkably,our catalyst shows an ultrahigh current density of 1 A cm^(-2) at an overpotential of only 388 mV,surpassing that of commercial Pt/C,while maintaining long-term stability.This material design strategy of similar stacking opens up new avenues of strain modulation and the deeper development of electrocatalysts.展开更多
Flow behavior and microstructure of a homogenized ZK60 magnesium alloy were investigated during compression in the temperature range of 250-400 ℃ and the strain rate range of 0.1-50 s^-1. The results showed that dyna...Flow behavior and microstructure of a homogenized ZK60 magnesium alloy were investigated during compression in the temperature range of 250-400 ℃ and the strain rate range of 0.1-50 s^-1. The results showed that dynamic recrystallization （DRX） developed mainly at grain boundaries at lower strain rate （0.1-1 s^-1）, while in the case of higher strain rate （10-50 s^-1）, DRX occurred extensively both at twins and grain boundaries at all temperature range, especially at temperature lower than 350 ℃, which resulted in a more homogeneous microstructure than that under other deformation conditions. The DRX extent determines the hot workability of the workpiece, therefore, hot deformation at the strain rate of 10-50 s^-1 and in the temperature range of 250-350 ℃ was desirable for ZK60 alloy. Twin induced DRX during high strain rate compression included three steps. Firstly, twins with high dislocation subdivided the initial grain, then dislocation arrays subdivided the twins into subgrains, and after that DRX took place with a further increase of strain.展开更多
The compressively strained InGaAs/InGaAsP quantum well distributed feedback laser with ridge-wave- guide is fabricated at 1.74μm. It is grown by low-pressure metal organic chemical vapor deposition（MOCVD）. A strain...The compressively strained InGaAs/InGaAsP quantum well distributed feedback laser with ridge-wave- guide is fabricated at 1.74μm. It is grown by low-pressure metal organic chemical vapor deposition（MOCVD）. A strain buffer layer is used to avoid indium segregation. The threshold current of the device uncoated with length of 300μm is 11.5mA. The maximum output power is 14mW at 100mA. A side mode suppression ratio of 35.5dB is obtained.展开更多
Dealloying by which the transition metal is partially or completely leached from an alloy precursor is an effective way to optimize the fundamental effects for further enhancing the electrocatalysis of a catalyst.Here...Dealloying by which the transition metal is partially or completely leached from an alloy precursor is an effective way to optimize the fundamental effects for further enhancing the electrocatalysis of a catalyst.Herein,to address the deficiencies associated with the commonly used dealloying methods,for example,electrochemical and sulfuric acid/nitric acid treatment,we report an acetic acid-assisted mild strategy to dealloy Cu atoms from the outer surface layers of CuPd alloy nanoparticles to achieve high-efficiency electrocatalysis for oxygen reduction and ethanol oxidation in an alkaline electrolyte.The leaching of Cu atoms by acetic acid exerts an additional compressive strain effect on the surface layers and exposes more active Pd atoms,which is beneficial for boosting the catalytic performance of a dealloyed catalyst for the oxygen reduction reaction(ORR)and the ethanol oxidation reaction(EOR).In particular,for ORR,the CuPd nanoparticles with a Pd/Cu molar ratio of 2:1 after acetic dealloying show a half-wave potential of 0.912 V(vs.RHE)and a mass activity of 0.213 AmgPd^(-1)at 0.9 V,respectively,while for EOR,the same dealloyed sample has a mass activity and a specific activity of 8.4 Amg^(-1)and 8.23 mA cm^(-2),respectively,much better than their dealloyed counterparts at other temperatures and commercial Pd/C as well as a Pt/C catalyst.展开更多
Superconducting thin films are widely used in superconducting quantum interferometers,microwave devices,etc.The electrical performance of a superconducting thin film is often affected by structural deformation or stre...Superconducting thin films are widely used in superconducting quantum interferometers,microwave devices,etc.The electrical performance of a superconducting thin film is often affected by structural deformation or stress.Based on four-point bending of a Cu-Be beam,we constructed a device that could apply uniaxial,uniform.compressive strain to a superconducting thin film at both room temperature and the temperature of liquid nitrogen.The thin film was placed into a slot carved in the Cu-Be beam.We optimized the size of this slot via numerical simulation.Our results indicated that the slot width was optimal when it was same as the width of the Cu-Be beam.Notably,the sample bended hardly after machining two slits along width direction on both sides of the slot.A YBa2Cu3O7-δSrTiO3(YBCO-STO)film was used as an example.It was loadedby the aforementioned device to determine its electrical characteristics as functions of the uniaxial-uniform-compressive strain.The optimized design allowed the sample to be compressed to a larger strain without breaking it.展开更多
A dent is a common type of defects for submarine pipeline.For submarine pipelines,high hydrostatic pressure and internal pressure are the main loads.Once pipelines bend due to complex subsea conditions,the compression...A dent is a common type of defects for submarine pipeline.For submarine pipelines,high hydrostatic pressure and internal pressure are the main loads.Once pipelines bend due to complex subsea conditions,the compression strain capacity may be exceeded.Research into the local buckling failure and accurate prediction of the compressive strain capacity are important.A finite element model of a pipeline with a dent is established.Local buckling failure under a bending moment is investigated,and the compressive strain capacity is calculated.The effects of different parameters on pipeline local buckling are analyzed.The results show that the dent depth,external pressure and internal pressure lead to different local buckling failure modes of the pipeline.A higher internal pressure indicates a larger compressive strain capacity,and the opposite is true for external pressure.When the ratio of external pressure to collapse pressure of intact pipeline is greater than 0.1,the deeper the dent,the greater the compressive strain capacity of the pipeline.And as the ratio is less than 0.1,the opposite is true.On the basis of these results,a regression equation for predicting the compressive strain capacity of a dented submarine pipeline is proposed,which can be referred to during the integrity assessment of a submarine pipeline.展开更多
Effects of strain rate and water-to-cement ratio on the dynamic compressive mechanical behavior of cement mortar are investigated by split Hopkinson pressure bar(SHPB) tests. 124 specimens are subjected to dynamic uni...Effects of strain rate and water-to-cement ratio on the dynamic compressive mechanical behavior of cement mortar are investigated by split Hopkinson pressure bar(SHPB) tests. 124 specimens are subjected to dynamic uniaxial compressive loadings.Strain rate sensitivity of the materials is measured in terms of failure modes, stress-strain curves, compressive strength, dynamic increase factor(DIF) and critical strain at peak stress. A significant change in the stress-strain response of the materials with each order of magnitude increase in strain rate is clearly seen from test results. The slope of the stress-strain curve after peak value for low water-to-cement ratio is steeper than that of high water-to-cement ratio mortar. The compressive strength increases with increasing strain rate. With increase in strain rate, the dynamic increase factor(DIF) increases. However, this increase in DIF with increase in strain rate does not appear to be a function of the water-to-cement ratio. The critical compressive strain increases with the 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
In order to investigate the influence of compressive strain on indium incorporation in In Al N and In Ga N ternary nitrides, In Al N/Ga N heterostructures and In Ga N films were grown by metal–organic chemical vapor ...In order to investigate the influence of compressive strain on indium incorporation in In Al N and In Ga N ternary nitrides, In Al N/Ga N heterostructures and In Ga N films were grown by metal–organic chemical vapor deposition. For the heterostructures, different compressive strains are produced by Ga N buffer layers grown on unpatterned and patterned sapphire substrates thanks to the distinct growth mode; while for the In Ga N films, compressive strains are changed by employing Al Ga N templates with different aluminum compositions. By various characterization methods, we find that the compressive strain will hamper the indium incorporation in both In Al N and In Ga N. Furthermore, compressive strain is conducive to suppress the non-uniform distribution of indium in In Ga N ternary alloys.展开更多
The Kapitza resistance is of fundamental importance for the thermal stability of the interface between the ceramic top coat and the thermal growth oxide layer in the thermal barrier coating structure,which is widely u...The Kapitza resistance is of fundamental importance for the thermal stability of the interface between the ceramic top coat and the thermal growth oxide layer in the thermal barrier coating structure,which is widely used to protect high-temperature components in current gas turbine engines.The top coat typically consists of the ZrO_(2)partially stabilized by 8%Y2O3(YSZ),and the main component of the thermal growth oxide isα-Al_(2)O_(3).In this work,the Kapitza resistance is found to be a small value of 0.69 m^(2)K/GW for the YSZ/α-Al_(2)O_(3)interface based on the heat dissipation simulation method.It indicates that the localization of thermal energy is rather weak,which is beneficial for the thermal stability of the YSZ/α-Al_(2)O_(3)interface.This Kapitza resistance can be further reduced to 0.50 m^(2)K/GW by a mechanical or thermal compressive strain of 8%.To explore the underlying mechanism for this strain effect,we analyze the phonon vibration and the microscopic deformation in the interface region.It is revealed that the interface becomes denser through the compression-induced twisting of some Al-O_(zr)and A1-O_(Al)chemical bonds in the interface region,which is responsible for the reduction in the Kapitza resistance.The temperature effect and crystal size effect on the Kapitza resistance of the YSZ/α-Al_(2)O_(3)interface are also systematically studied.These findings shall provide valuable information for further understanding of the thermal conductivity and thermal stability of the thermal barrier coating structures.展开更多
The stabilities and migration behaviors of 1/2<110>perfect vacancy loops in various FCC metals are studied by molecular dynamics(MD)simulations.Compression strain can suppress the spontaneous structural transfor...The stabilities and migration behaviors of 1/2<110>perfect vacancy loops in various FCC metals are studied by molecular dynamics(MD)simulations.Compression strain can suppress the spontaneous structural transformation from perfect vacancy loops to sessile stacking fault tetrahedra(SFTs).Instead,an intermediate stable structure containing four stacking faults and exhibiting one-dimensional(1-D)fast migration is formed.The migration is essentially enhanced with the compression strain,the corresponding migration barrier can be as low as 0.002 eV for perfect loop containing 100 vacancies in Cu under 4%compression strain.Furthermore,the stabilities and mobilities of intermediate structures are increased with the decrease of stacking fault energy(SFE)for Au,Cu,Ni and Al.Two different migration modes,including collective glide and change of habit planes,are observed,the dominant migration behavior depends on the loop size and compression strain.The energetics of 1/2<110>perfect vacancy loops and SFTs,as well as the energy landscapes of two 1-D migration modes,are calculated to interpret its structural transformation and migration behaviors.This study first reveals the fast migration behaviors of perfect vacancy loops in FCC metals and the underlying mechanisms,especially the important role of compression strain,which would provide important clues for understanding the variations of microstructures and properties related with vacancy behaviors.展开更多
The exploitation of durable and highly active Pt-based electrocatalysts for the oxygen reduction reaction(ORR)is essential for the commercialization of proton exchange membrane fuel cells(PEMFCs).Herein,we designed Pt...The exploitation of durable and highly active Pt-based electrocatalysts for the oxygen reduction reaction(ORR)is essential for the commercialization of proton exchange membrane fuel cells(PEMFCs).Herein,we designed Pt@Pt_(3)Ti core-shell nanoparticles with atomic-controllable shells through precise thermal diffusing Ti into Pt nanoparticles for effective and durable ORR.Combining theoretical and experiment analysis,we found that the lattice strain of Pt_(3)Ti shells can be tailored by precisely controlling the thick-ness of Pt_(3)Ti shell in atomic-scale on account of the lattice constant difference between Pt and Pt_(3)Ti to optimize adsorption properties of Pt_(3)Ti for ORR intermediates,thus enhancing its performance.The Pt@Pt_(3)Ti catalyst with one-atomic Pt_(3)Ti shell(Pt@1L-Pt_(3)Ti/TiO_(2)-C)demonstrates excellent performance with mass activity of 592 mA mgpt-1 and durability nearly 19.5-fold that of commercial Pt/C with negligible decay(2%)after 30,000 potential cycles(0.6-1.0 V vs.RHE).Notably,at higher potential cycles(1.0 V-1.5 V vs.RHE),Pt@1L-Pt_(3)Ti/TiO_(2)-C also showed far superior durability than Pt/C(9.6%decayed while 54.8% for commercial Pt/C).This excellent stability is derived from the intrinsic stability of Pt_(3)Ti alloy and the confinement effect of TiO_(2)-C.The catalyst's enhancement was further confirmed in PEMFC configuration.展开更多
High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation.Among them,tungsten-based alloys demonstrate exceptional potential owing to their superior irradiat...High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation.Among them,tungsten-based alloys demonstrate exceptional potential owing to their superior irradiation resistance.Recent experimental studies have demonstrated that W-Ta-Cr-V alloys exhibit excellent irradiation resistance under helium(He)ion irradiation.However,the underlying mechanisms,especially the migration behavior of He atoms,remain unclear.In this work,the influences of uniaxial tensile and compressive strain on He migration in W-Ta-Cr-V complex alloys have been systematically studied through first-principles calculations.Our results demonstrate that He atoms preferentially occupy the tetrahedral interstitial sites,with interstitial formation energies significantly reduced compared to pure W.The introduction of Ta,Cr,and V alloying elements markedly increases the He migration barriers,effectively suppressing He diffusion.Compressive strain increases the migration barriers,inhibiting He bubbles nucleation and growth,while tensile strain decreases the barriers,facilitating bubble formation.Compared to pure W,the W-Ta-Cr-V alloys exhibit both lower He interstitial formation energies and higher migration barriers,with further enhancement under compressive strain.Specifically,compressive strain of 6%increases the He migration barrier of the W-Ta-Cr-V alloy by 0.166 e V,which further widens the difference relative to pure W.These findings provide a theoretical explanation for the superior irradiation resistance of tungsten-based alloys observed experimentally and promote the understanding of irradiation damage in these alloys under strain.展开更多
The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on m...The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled transformation-induced plasticity steel.The thermomechanical-controlled processing was carried out with thermomechanical simulation machine,and the samples were compressed to compression strains of 0,0.15,0.25 and 0.35 at compression temperatures of 850,900 and 950°C.The results showed that the volume fraction of polygonal ferrite increased with the increasing compression strain,while the volume fraction of retained austenite reached the maximum value at compression strain of 0.25.The volume fraction of polygonal ferrite decreased with the increasing compression temperature,whereas the volume fraction of retained austenite possessed the maximum value at compression temperature of 850°C.Some granular retained austenite was present in uncompressed samples,and some pearlite appeared at large compression strain,while the hardness of the samples exhibited the similar variation tendency to the volume fraction of retained austenite.展开更多
Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines...Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength, which are under different conditions, including pure bending and bending combined with internal pressure. Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes. In parametric analysis, a series of parameters,including pipe geometrical dimension, pipe material properties and internal pressure, were selected to study their influences on the critical bending moment, critical compressive stress and critical compressive strain of pipes.Especially the hardening exponent of pipe material was introduced to the parameter analysis by using the Ramberg–Osgood constitutive model. Results showed that geometrical dimensions, material and internal pressure can exert similar effects on the critical bending moment and critical compressive stress, which have different, even reverse effects on the critical compressive strain. Based on these analyses, more accurate design models of critical bending moment and critical compressive stress have been proposed for high-strength pipelines under bendingconditions, which provide theoretical methods for highstrength pipeline engineering.展开更多
In order to investigate the deformation and failure of reinforced sand, and the reinforcing mechanism of flexible and rigid reinforcement, a set of plane strain compression tests of dense Toyoura reinforced sand with ...In order to investigate the deformation and failure of reinforced sand, and the reinforcing mechanism of flexible and rigid reinforcement, a set of plane strain compression tests of dense Toyoura reinforced sand with planar reinforcement of a wide range of stiffness were analysed by a nonlinear finite element method. The analysis was incorporated into an energy-based elasto-plastic constitutive model for sand to develop a stress path-independent work-hardening parameter based on the modified plastic strain energy concept. Numerical results indicate that the global stress-strain relations of sand specimens are reinforced by using relatively flexible and rigid reinforcement, and an unreinforced sand specimen can be reasonably simulated by the current finite element method. It is also found that the reinforcing mechanism and progressive failure with a development of shear bands in reinforced sand can be reasonably examined by the finite element method.展开更多
文摘Recrystallization behavior of a low carbon X70 pipeline steel was studied in the plane strain compression condition. It was found that the dynamic recovery but no dynamic recrystal- lization occurred in the current experimental condition. A method for examining the prior austenite grain boundary corrosion was supposed.
基金the Young Elite Scientists Sponsorship Program by CAST(2021QNRC001)Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX0557,cstb2023nscq-msx0979)+3 种基金Talent Introduction of Chongqing University of Science and Technology(ckrc2021050,ckrc20230401,ckrc2021053)the Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202201532,KJQN202301542)the National Natural Science Foundation of China(22109016)Open Research Fund of CNMGE Platform&NSCC-TJ(CNMGE2023016).
文摘The development of efficient and durable electrocatalysts for oxygen reduction reaction(ORR)holds a pivotal significance in the successful commercialization of proton exchange membrane fuel cells(PEMFCs)but is still challenging.Herein,we report a worm-liked PtCu nanocrystals dispersed on nitrogen-doped carbon hollow microspheres(Pt_(0.38)Cu_(0.62)/N-HCS).Benefiting from its structural and compositional advantages,the resulting Pt_(0.38)Cu_(0.62)/N-HCS catalyst delivers exceptional electrocatalytic activity for ORR,with a half-wave potential(E_(1/2))of 0.837 V,a mass activity of 0.672 A mgPt^(-1),and a Tafel slope of 50.66 mV dec^(-1),surpassing that of commercial Pt/C.Moreover,the Pt_(0.38)Cu_(0.62)/N-HCS follows the desired four-electron transfer mechanism throughout the ORR process,thereby displaying a high selectivity for direct reduction of O_(2)to H_(2)O.Remarkably,this catalyst also showcases high stability,with only a 25 mV drop in E_(1/2)after 10,000 cycles in an acidic electrolyte.Theoretical calculations elucidate the incorporation of Cu into Pt lattice induces compressive strain,which effectively tailors the d band center of Pt active sites and strengthens the surface chemisorption of O_(2)molecules on PtCu alloys.Consequently,the Pt_(0.38)Cu_(0.62)/N-HCS catalyst exhibits an improved ability to adsorb O_(2)molecules on its surface,accelerating the reaction kinetics of O_(2)conversion to*OOH.Additionally,Cu atoms,not only serving as sacrificial anode,undergo preferential oxidation during PEMFCs operation when compared to Pt,but also the stable Cu species in PtCu alloys contributes significantly to maintaining the strain effect,collectively enhancing both activity and durability.Overall,this research offers an effective and promising approach to enhance the activity and stability of Pt-based ORR electrocatalysts in PEMFCs.
基金Self-innovation Capability Construction of Jilin Province Development and Reform Commission,Grant/Award Number:2021C026National Natural Science Foundation of China,Grant/Award Numbers:12034002,22202080,22279044,51872116Jilin Province Science and Technology Development Program,Grant/Award Number:20210301009GX。
文摘Strain effects have garnered significant attention in catalytic applications due to their ability to modulate the electronic structure and surface adsorption properties of catalysts.In this study,we propose a novel approach called“similar stacking”for stress modulation,achieved through the loading of Co_(2)P on Ni_(2)P(Ni_(2)P/Co_(2)P).Theoretical simulations reveal that the compressive strain induced by Co_(2)P influences orbital overlap and electron transfer with hydrogen atoms.Furthermore,the number of stacked layers can be adjusted by varying the precursor soaking time,which further modulates the strain range and hydrogen adsorption.Under a 2-h soaking condition,the strain effect proves favorable for efficient hydrogen production.Experimental characterizations using X-ray diffraction,high-angel annular dark-field scanning transmission election microscope(HAADF-STEM),and X-ray absorption near-edge structure spectroscopy successfully demonstrate lattice contraction of Co_(2)P and bond length shortening of Co-P.Remarkably,our catalyst shows an ultrahigh current density of 1 A cm^(-2) at an overpotential of only 388 mV,surpassing that of commercial Pt/C,while maintaining long-term stability.This material design strategy of similar stacking opens up new avenues of strain modulation and the deeper development of electrocatalysts.
基金Project (14JJ6047) supported by the Natural Science Foundation of Hunan Province,ChinaProject (51274092) supported by the National Natural Science Foundation of ChinaProject (20120161110040) supported by the Doctoral Program of Higher Education ofChina
文摘Flow behavior and microstructure of a homogenized ZK60 magnesium alloy were investigated during compression in the temperature range of 250-400 ℃ and the strain rate range of 0.1-50 s^-1. The results showed that dynamic recrystallization （DRX） developed mainly at grain boundaries at lower strain rate （0.1-1 s^-1）, while in the case of higher strain rate （10-50 s^-1）, DRX occurred extensively both at twins and grain boundaries at all temperature range, especially at temperature lower than 350 ℃, which resulted in a more homogeneous microstructure than that under other deformation conditions. The DRX extent determines the hot workability of the workpiece, therefore, hot deformation at the strain rate of 10-50 s^-1 and in the temperature range of 250-350 ℃ was desirable for ZK60 alloy. Twin induced DRX during high strain rate compression included three steps. Firstly, twins with high dislocation subdivided the initial grain, then dislocation arrays subdivided the twins into subgrains, and after that DRX took place with a further increase of strain.
文摘The compressively strained InGaAs/InGaAsP quantum well distributed feedback laser with ridge-wave- guide is fabricated at 1.74μm. It is grown by low-pressure metal organic chemical vapor deposition（MOCVD）. A strain buffer layer is used to avoid indium segregation. The threshold current of the device uncoated with length of 300μm is 11.5mA. The maximum output power is 14mW at 100mA. A side mode suppression ratio of 35.5dB is obtained.
基金the financial support provided by the National Natural Science Foundation of China(22075290,21972068,52164028)the Beijing Natural Science Foundation(Z200012)+3 种基金the State Key Laboratory of Multiphase Complex Systemsthe Institute of Process Engineeringthe Chinese Academy of Sciences(MPCS-2021-A-05)the Nanjing IPE Institute of Green Manufacturing Industry(E0010725).
文摘Dealloying by which the transition metal is partially or completely leached from an alloy precursor is an effective way to optimize the fundamental effects for further enhancing the electrocatalysis of a catalyst.Herein,to address the deficiencies associated with the commonly used dealloying methods,for example,electrochemical and sulfuric acid/nitric acid treatment,we report an acetic acid-assisted mild strategy to dealloy Cu atoms from the outer surface layers of CuPd alloy nanoparticles to achieve high-efficiency electrocatalysis for oxygen reduction and ethanol oxidation in an alkaline electrolyte.The leaching of Cu atoms by acetic acid exerts an additional compressive strain effect on the surface layers and exposes more active Pd atoms,which is beneficial for boosting the catalytic performance of a dealloyed catalyst for the oxygen reduction reaction(ORR)and the ethanol oxidation reaction(EOR).In particular,for ORR,the CuPd nanoparticles with a Pd/Cu molar ratio of 2:1 after acetic dealloying show a half-wave potential of 0.912 V(vs.RHE)and a mass activity of 0.213 AmgPd^(-1)at 0.9 V,respectively,while for EOR,the same dealloyed sample has a mass activity and a specific activity of 8.4 Amg^(-1)and 8.23 mA cm^(-2),respectively,much better than their dealloyed counterparts at other temperatures and commercial Pd/C as well as a Pt/C catalyst.
基金the National Natural Science Foundation of China(Grants 11622217,11872196,and11902130)the Fundamental ResearchFunds for the Central Universities(Grant lzujbky-2018-9).
文摘Superconducting thin films are widely used in superconducting quantum interferometers,microwave devices,etc.The electrical performance of a superconducting thin film is often affected by structural deformation or stress.Based on four-point bending of a Cu-Be beam,we constructed a device that could apply uniaxial,uniform.compressive strain to a superconducting thin film at both room temperature and the temperature of liquid nitrogen.The thin film was placed into a slot carved in the Cu-Be beam.We optimized the size of this slot via numerical simulation.Our results indicated that the slot width was optimal when it was same as the width of the Cu-Be beam.Notably,the sample bended hardly after machining two slits along width direction on both sides of the slot.A YBa2Cu3O7-δSrTiO3(YBCO-STO)film was used as an example.It was loadedby the aforementioned device to determine its electrical characteristics as functions of the uniaxial-uniform-compressive strain.The optimized design allowed the sample to be compressed to a larger strain without breaking it.
基金financially supported by the National Natural Science Foundation of China(Grant No.52171285)。
文摘A dent is a common type of defects for submarine pipeline.For submarine pipelines,high hydrostatic pressure and internal pressure are the main loads.Once pipelines bend due to complex subsea conditions,the compression strain capacity may be exceeded.Research into the local buckling failure and accurate prediction of the compressive strain capacity are important.A finite element model of a pipeline with a dent is established.Local buckling failure under a bending moment is investigated,and the compressive strain capacity is calculated.The effects of different parameters on pipeline local buckling are analyzed.The results show that the dent depth,external pressure and internal pressure lead to different local buckling failure modes of the pipeline.A higher internal pressure indicates a larger compressive strain capacity,and the opposite is true for external pressure.When the ratio of external pressure to collapse pressure of intact pipeline is greater than 0.1,the deeper the dent,the greater the compressive strain capacity of the pipeline.And as the ratio is less than 0.1,the opposite is true.On the basis of these results,a regression equation for predicting the compressive strain capacity of a dented submarine pipeline is proposed,which can be referred to during the integrity assessment of a submarine pipeline.
基金Project(51479048) supported by National Natural Science Foundation of China
文摘Effects of strain rate and water-to-cement ratio on the dynamic compressive mechanical behavior of cement mortar are investigated by split Hopkinson pressure bar(SHPB) tests. 124 specimens are subjected to dynamic uniaxial compressive loadings.Strain rate sensitivity of the materials is measured in terms of failure modes, stress-strain curves, compressive strength, dynamic increase factor(DIF) and critical strain at peak stress. A significant change in the stress-strain response of the materials with each order of magnitude increase in strain rate is clearly seen from test results. The slope of the stress-strain curve after peak value for low water-to-cement ratio is steeper than that of high water-to-cement ratio mortar. The compressive strength increases with increasing strain rate. With increase in strain rate, the dynamic increase factor(DIF) increases. However, this increase in DIF with increase in strain rate does not appear to be a function of the water-to-cement ratio. The critical compressive strain increases with the 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 Nos.61404099 and 61306017)the Fundamental Research Funds for the Central Universities,China(Grant No.JB141101)
文摘In order to investigate the influence of compressive strain on indium incorporation in In Al N and In Ga N ternary nitrides, In Al N/Ga N heterostructures and In Ga N films were grown by metal–organic chemical vapor deposition. For the heterostructures, different compressive strains are produced by Ga N buffer layers grown on unpatterned and patterned sapphire substrates thanks to the distinct growth mode; while for the In Ga N films, compressive strains are changed by employing Al Ga N templates with different aluminum compositions. By various characterization methods, we find that the compressive strain will hamper the indium incorporation in both In Al N and In Ga N. Furthermore, compressive strain is conducive to suppress the non-uniform distribution of indium in In Ga N ternary alloys.
基金the National Natural Science Foundation of China(Grant Nos.11822206 and 12072182)Innovation Program of the Shanghai Municipal Education Commission(Grant No.2017-01-07-00-09-E00019)。
文摘The Kapitza resistance is of fundamental importance for the thermal stability of the interface between the ceramic top coat and the thermal growth oxide layer in the thermal barrier coating structure,which is widely used to protect high-temperature components in current gas turbine engines.The top coat typically consists of the ZrO_(2)partially stabilized by 8%Y2O3(YSZ),and the main component of the thermal growth oxide isα-Al_(2)O_(3).In this work,the Kapitza resistance is found to be a small value of 0.69 m^(2)K/GW for the YSZ/α-Al_(2)O_(3)interface based on the heat dissipation simulation method.It indicates that the localization of thermal energy is rather weak,which is beneficial for the thermal stability of the YSZ/α-Al_(2)O_(3)interface.This Kapitza resistance can be further reduced to 0.50 m^(2)K/GW by a mechanical or thermal compressive strain of 8%.To explore the underlying mechanism for this strain effect,we analyze the phonon vibration and the microscopic deformation in the interface region.It is revealed that the interface becomes denser through the compression-induced twisting of some Al-O_(zr)and A1-O_(Al)chemical bonds in the interface region,which is responsible for the reduction in the Kapitza resistance.The temperature effect and crystal size effect on the Kapitza resistance of the YSZ/α-Al_(2)O_(3)interface are also systematically studied.These findings shall provide valuable information for further understanding of the thermal conductivity and thermal stability of the thermal barrier coating structures.
基金supported by the National Magnetic Confinement Fusion Energy Research Project(No.2024YFE03150000)the National Natural Science Foundation of China(Nos.11905057,11935004,and 12175059)the Natural Science Foundation of Hunan Province(No.2021JJ30002).
文摘The stabilities and migration behaviors of 1/2<110>perfect vacancy loops in various FCC metals are studied by molecular dynamics(MD)simulations.Compression strain can suppress the spontaneous structural transformation from perfect vacancy loops to sessile stacking fault tetrahedra(SFTs).Instead,an intermediate stable structure containing four stacking faults and exhibiting one-dimensional(1-D)fast migration is formed.The migration is essentially enhanced with the compression strain,the corresponding migration barrier can be as low as 0.002 eV for perfect loop containing 100 vacancies in Cu under 4%compression strain.Furthermore,the stabilities and mobilities of intermediate structures are increased with the decrease of stacking fault energy(SFE)for Au,Cu,Ni and Al.Two different migration modes,including collective glide and change of habit planes,are observed,the dominant migration behavior depends on the loop size and compression strain.The energetics of 1/2<110>perfect vacancy loops and SFTs,as well as the energy landscapes of two 1-D migration modes,are calculated to interpret its structural transformation and migration behaviors.This study first reveals the fast migration behaviors of perfect vacancy loops in FCC metals and the underlying mechanisms,especially the important role of compression strain,which would provide important clues for understanding the variations of microstructures and properties related with vacancy behaviors.
基金supported by the National Natural Science Foundation of China(No.21875039)the Project on the Integration of Industry-Education-Research of Fujian Province(No.2021H6020)the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology).
文摘The exploitation of durable and highly active Pt-based electrocatalysts for the oxygen reduction reaction(ORR)is essential for the commercialization of proton exchange membrane fuel cells(PEMFCs).Herein,we designed Pt@Pt_(3)Ti core-shell nanoparticles with atomic-controllable shells through precise thermal diffusing Ti into Pt nanoparticles for effective and durable ORR.Combining theoretical and experiment analysis,we found that the lattice strain of Pt_(3)Ti shells can be tailored by precisely controlling the thick-ness of Pt_(3)Ti shell in atomic-scale on account of the lattice constant difference between Pt and Pt_(3)Ti to optimize adsorption properties of Pt_(3)Ti for ORR intermediates,thus enhancing its performance.The Pt@Pt_(3)Ti catalyst with one-atomic Pt_(3)Ti shell(Pt@1L-Pt_(3)Ti/TiO_(2)-C)demonstrates excellent performance with mass activity of 592 mA mgpt-1 and durability nearly 19.5-fold that of commercial Pt/C with negligible decay(2%)after 30,000 potential cycles(0.6-1.0 V vs.RHE).Notably,at higher potential cycles(1.0 V-1.5 V vs.RHE),Pt@1L-Pt_(3)Ti/TiO_(2)-C also showed far superior durability than Pt/C(9.6%decayed while 54.8% for commercial Pt/C).This excellent stability is derived from the intrinsic stability of Pt_(3)Ti alloy and the confinement effect of TiO_(2)-C.The catalyst's enhancement was further confirmed in PEMFC configuration.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11505003 and 52325103)the Anhui Provincial Natural Science Foundation(Grant No.2108085MA25)。
文摘High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation.Among them,tungsten-based alloys demonstrate exceptional potential owing to their superior irradiation resistance.Recent experimental studies have demonstrated that W-Ta-Cr-V alloys exhibit excellent irradiation resistance under helium(He)ion irradiation.However,the underlying mechanisms,especially the migration behavior of He atoms,remain unclear.In this work,the influences of uniaxial tensile and compressive strain on He migration in W-Ta-Cr-V complex alloys have been systematically studied through first-principles calculations.Our results demonstrate that He atoms preferentially occupy the tetrahedral interstitial sites,with interstitial formation energies significantly reduced compared to pure W.The introduction of Ta,Cr,and V alloying elements markedly increases the He migration barriers,effectively suppressing He diffusion.Compressive strain increases the migration barriers,inhibiting He bubbles nucleation and growth,while tensile strain decreases the barriers,facilitating bubble formation.Compared to pure W,the W-Ta-Cr-V alloys exhibit both lower He interstitial formation energies and higher migration barriers,with further enhancement under compressive strain.Specifically,compressive strain of 6%increases the He migration barrier of the W-Ta-Cr-V alloy by 0.166 e V,which further widens the difference relative to pure W.These findings provide a theoretical explanation for the superior irradiation resistance of tungsten-based alloys observed experimentally and promote the understanding of irradiation damage in these alloys under strain.
基金the support from National Natural Science Foundation of China(No.51504063).R.D.K.Misra,an honorary professor,also acknowledges the continued collaboration with Northeastern University by providing guidance to students in research.
文摘The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled transformation-induced plasticity steel.The thermomechanical-controlled processing was carried out with thermomechanical simulation machine,and the samples were compressed to compression strains of 0,0.15,0.25 and 0.35 at compression temperatures of 850,900 and 950°C.The results showed that the volume fraction of polygonal ferrite increased with the increasing compression strain,while the volume fraction of retained austenite reached the maximum value at compression strain of 0.25.The volume fraction of polygonal ferrite decreased with the increasing compression temperature,whereas the volume fraction of retained austenite possessed the maximum value at compression temperature of 850°C.Some granular retained austenite was present in uncompressed samples,and some pearlite appeared at large compression strain,while the hardness of the samples exhibited the similar variation tendency to the volume fraction of retained austenite.
基金supported by the National ScienceTechnology Support Plan Projects of China, under Award No. 2015BAK16B02
文摘Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength, which are under different conditions, including pure bending and bending combined with internal pressure. Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes. In parametric analysis, a series of parameters,including pipe geometrical dimension, pipe material properties and internal pressure, were selected to study their influences on the critical bending moment, critical compressive stress and critical compressive strain of pipes.Especially the hardening exponent of pipe material was introduced to the parameter analysis by using the Ramberg–Osgood constitutive model. Results showed that geometrical dimensions, material and internal pressure can exert similar effects on the critical bending moment and critical compressive stress, which have different, even reverse effects on the critical compressive strain. Based on these analyses, more accurate design models of critical bending moment and critical compressive stress have been proposed for high-strength pipelines under bendingconditions, which provide theoretical methods for highstrength pipeline engineering.
基金Project supported by the Association of International Education of Japan
文摘In order to investigate the deformation and failure of reinforced sand, and the reinforcing mechanism of flexible and rigid reinforcement, a set of plane strain compression tests of dense Toyoura reinforced sand with planar reinforcement of a wide range of stiffness were analysed by a nonlinear finite element method. The analysis was incorporated into an energy-based elasto-plastic constitutive model for sand to develop a stress path-independent work-hardening parameter based on the modified plastic strain energy concept. Numerical results indicate that the global stress-strain relations of sand specimens are reinforced by using relatively flexible and rigid reinforcement, and an unreinforced sand specimen can be reasonably simulated by the current finite element method. It is also found that the reinforcing mechanism and progressive failure with a development of shear bands in reinforced sand can be reasonably examined by the finite element method.
