A large number of anomalous extension twins,with low or even negative twinning Schmid factors,were found to nucleate and grow in a strongly textured Mg-1Al alloy during tensile deformation along the extruded direction...A large number of anomalous extension twins,with low or even negative twinning Schmid factors,were found to nucleate and grow in a strongly textured Mg-1Al alloy during tensile deformation along the extruded direction.The deformation mechanisms responsible for this behaviour were investigated through in-situ electron back-scattered diffraction,grain reference orientation deviation,and slip trace-modified lattice rotation.It was found that anomalous extension twins nucleated mainly at the onset of plastic deformation at or near grain boundary triple junctions.They were associated with the severe strain incompatibility between neighbour grains as a result from the differentbasal slip-induced lattice rotations.Moreover,the anomalous twins were able to grow with the applied strain due to the continuous activation ofbasal slip in different neighbour grains,which enhanced the strain incompatibility.These results reveal the complexity of the deformation mechanisms in Mg alloys at the local level when deformed along hard orientations.展开更多
High flammability of polymers has become a major issue which has restricted its applications.Recently,highly crystalline materials and metal–organic frameworks(MOFs),which consisted of metal ions and organic linkers,...High flammability of polymers has become a major issue which has restricted its applications.Recently,highly crystalline materials and metal–organic frameworks(MOFs),which consisted of metal ions and organic linkers,have been intensively employed as novel fire retardants(FRs)for a variety of polymers(MOF/polymer).The MOFs possessed abundant transition metal species,fire-retardant elements and potential carbon source accompanied with the facile tuning of the structure and property,making MOF,its derivatives and MOF hybrids promising for fire retardancy research.The recent progress and strategies to prepare MOF-based FRs are emphasized and summarized.The fire retardancy mechanisms of MOF/polymer composites are explained,which may guide the future design for efficient MOF-based FRs.Finally,the challenges and prospects related to different MOFbased FRs are also discussed and aim to provide a fast and holistic overview,which is beneficial for researchers to quickly get up to speed with the latest development in this field.展开更多
This work investigates the effect of solid solution on ductility and on the activation of individual deformation mechanisms at moderate temperatures and at quasi-static strain rates in Mg-Zn and Mg-Al alloys. With tha...This work investigates the effect of solid solution on ductility and on the activation of individual deformation mechanisms at moderate temperatures and at quasi-static strain rates in Mg-Zn and Mg-Al alloys. With that aim, four solid solution Mg-Zn and Mg-Al binary alloy ingots containing 1 and 2 wt.% solute atoms were subjected to hot rolling and subsequent annealing to generate polycrystals with similar average grain size and basal-type texture for each composition. The activity of the different slip systems after tensile testing at 150°C and at 250°C was evaluated in pure Mg and in the alloys by EBSD-assisted slip trace analysis. In addition, segregation of Zn and Al atoms at grain boundaries during the thermo-mechanical processing was characterized by HAADF-STEM and EDX. It was found that while the addition of Al and Zn atoms to pure Mg does not lead to major changes in the mechanical strength at the investigated temperatures, it does enhance ductility significantly, especially at 250℃. Our results show that this increase in ductility cannot be attributed to a higher activation of non-basal systems in the alloys, as reported earlier, as the incidence of non-basal systems is indeed considerably higher in pure Mg. This work suggests, on the contrary, that the ductility increase may be attributed to the presence of a more homogenous basal activity in the alloys due to a lower degree of orientation clustering, to grain boundary solute segregation, and to a higher slip diffusivity at grain interiors.展开更多
Early-stage fire-warning systems(EFWSs)have attracted significant attention owing to their superiority in detecting fire situations occurring in the pre-combustion process.Substantial progress on EFWSs has been achiev...Early-stage fire-warning systems(EFWSs)have attracted significant attention owing to their superiority in detecting fire situations occurring in the pre-combustion process.Substantial progress on EFWSs has been achieved recently,and they have presented a considerable possibility for more evacuation time to control constant unintentional fire hazards in our daily life.This review mainly makes a comprehensive summary of the current EFWSs,including the working mechanisms and their performance.According to the different working mechanisms,fire alarms can be classified into graphene oxide-based fire alarms,semiconductor-based fire alarms,thermoelectric-based fire alarms,and fire alarms on other working mechanisms.Finally,the challenge and prospect for EFWSs are briefly provided by comparing the art of state of fire alarms.This work can propose a more comprehensive understanding of EFWSs and a guideline for the cutting-edge development direction of EFWSs for readers.展开更多
Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors,and thus realize both high energy density and power density in a single configuration.Nevertheles...Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors,and thus realize both high energy density and power density in a single configuration.Nevertheless,applications of SICs are severely restricted by their insufficient energy densities (<100Wh/kg) resulted from the kinetics imbalance between cathodes and anodes.Herein,we report a nanograin-boundary-rich hierarchical Co_(3)O_(4) nanorod anode composed of~20 nm nanocrystallites.Extreme pseudocapacitance (up to 72%@1.0 mV/s) is achieved through nanograin-boundary-induced pseudocapacitive-type Na^(+) storage process.Co_(3)O_(4) nanorod anode delivers in this case highly reversible capacity (810 mAh/g@0.025 A/g),excellent rate capability (335 mAh/g@5.0 A/g),and improved cycle stability (100 cycles@1.0 A/g with negligible capacity degradation).The outstanding performance can be credited to the hierarchical morphology of Co_(3)O_(4) nanorods and the well-designed nanograinboundaries between nanocrystallites that avoid particle agglomeration,induce pseudocapacitive-type Na^(+) storage,and accommodate volume variation during sodiation-desodiation processes.Nitrogendoping of the Co_(3)O_(4) nanorods not only generates defects for extra surficial Na^(+) storage but also increases the electronic conductivity for efficient charge separation and lowers energy barrier for Na^(+) intercalation.Synergy of conventional reaction mechanism and pseudocapacitive-type Na^(+) storage enables high specific capacity,rapid Na^(+) diffusion,and improved structural stability of the Co_(3)O_(4) nanorod electrode.The SIC integrating this highly pseudocapacitive anode and activated carbon cathode delivers exceptional energy density (175 Wh/kg@40 W/kg),power density (6632 W/kg@37 Wh/kg),cycle life (6000 cycles@1.0 A/g with a capacity retention of 81%),and coulombic efficiency (~100%).展开更多
Although in recent years glass fibre reinforced cement (GRC) has been used in buildings and infrastructure, its application in structural elements has been somewhat restricted due to the worsening of its mechanical pr...Although in recent years glass fibre reinforced cement (GRC) has been used in buildings and infrastructure, its application in structural elements has been somewhat restricted due to the worsening of its mechanical properties with ageing and the limited data available related with its fracture energy. With the aim of developing existing knowledge of GRC, the fracture energy in an in-plane and out-of-plane direction of the panel has been obtained. Three types of GRC with different formulations have been tested. The results showed that the fracture energy of a GRC with a 25% addition of a pozzolanic admixture is 40% and 8% higher than a standard GRC in, respectively, in-plane and out-of-plane directions. Similarly, an addition of 25% of thermal-treated kaolin to a standard GRC increases its fracture energy up to 490% and 400%, to the corresponding orientation. The use of digital image correlation (DIC) in the fracture test analysis has permitted a description of the damaging patterns and explanation of the behaviours identified in the fracture tests performed. The multi-cracking process that appears explains the higher fracture energy found in the GRC with an addition of 25% of the aforementioned thermal-treated kaolin. The analysis performed by means of DIC and the results obtained showed GRC with an addition of 25% of thermal-treated kaolin to be the most suitable formulation for possible future structural applications with a short life span in horizontal and vertical elements.展开更多
Twin nucleation in textured Mg alloys was studied by means of electron back-scattered diffraction in samples deformed in tension along different orientations in more than 3000 grains.In addition,28 relevant parameters...Twin nucleation in textured Mg alloys was studied by means of electron back-scattered diffraction in samples deformed in tension along different orientations in more than 3000 grains.In addition,28 relevant parameters,categorized in four different groups(loading condition,grain shape,apparent Schmid factors,and grain boundary features)were also recorded for each grain.This information was used to train supervised machine learning classification models to analyze the influence of the microstructural features on the nucleation of extension twins in Mg alloys.It was found twin nucleation is favored in larger grains and in grains with high twinning Schmid factors,but also that twins may form in the grains with very low or even negative Schmid factors for twinning if they have at least one smaller neighboring grain and another one(or the same)that is more rigid.Moreover,twinning of small grains with high twinning Schmid factors is favored if they have low basal slip Schmid factors and have at least one neighboring grain with a high basal slip Schmid factor that will deform easily.These results reveal the role of many-body relationships,such as differences in stiffness and size between a given grain and its neighbors,to assess extension twin nucleation in grains unfavorably oriented for twinning.展开更多
Ti additions in Cu–Cr–Zr alloys are useful for achieving high mechanical properties.In this work,the influence of Ti contents(0.25 wt%,0.6 wt%,and 1.02 wt%)on the microstructure,mechanical,and electrical properties ...Ti additions in Cu–Cr–Zr alloys are useful for achieving high mechanical properties.In this work,the influence of Ti contents(0.25 wt%,0.6 wt%,and 1.02 wt%)on the microstructure,mechanical,and electrical properties of Cu–Cr–Zr alloys has been investigated experimentally,along with thermodynamic and kinetic calculations.The electrical conductivity decreased but the hardness/strength increased with increasing Ti content.The lower electrical conductivity is due to increased electron scattering through the solution of more Ti atoms in the Cu matrix.As for the higher hardness/strength,it is mainly owing to higher dislocation density and finer FCC-Cr precipitates.Furthermore,a model considering the size distributions of precipitates is adopted to calculate precipitation strengthening quantitatively.The calculated yield strengths are consistent with the experimental ones for the alloys.The thermodynamic and kinetic calculations reveal that increasing Ti content can facilitate the nucleation of FCC-Cr but enhance its activation energy,hence hindering the growth process.The present work study can provide an effective strategy for producing copper alloys with expected performance.展开更多
Optimization of the intermetallic layer thickness and the suppression of interfacial defects are key elements to improve the load bearing capacity of dissimilar joints. However, till date we do not have a systematic t...Optimization of the intermetallic layer thickness and the suppression of interfacial defects are key elements to improve the load bearing capacity of dissimilar joints. However, till date we do not have a systematic tool to investigate the dissimilar joints and the intermetallic properties produced by a welding condition. Friction Melt Bonding (FMB) is a recently developed technique for joining dissimilar metals that also does not exempt to these challenges. The FMB of DP980 and A16061-T6 was investigated using a new physical simulation tool, based on Gleeble thermo-mechanical simulator, to understand the effect of individual parameter on the intermetallic formation. The proposed method demonstrates its capability in reproducing the intermetallic characteristics, including the thickness of intermetallic bonding layer, the morphology and texture of its constituents (Fe2AU and Fe4Ali3), as well as their nanohardness and reduced modulus. The advantages of physical simulation tool can enable novel developing routes for the development of dissimilar metal joining processes and facilitate to reach the requiring load bearing capacity of the joints.展开更多
基金supported by the project(MAD2DCM)-IMDEA Materials funded by Comunidad de Madrid and by the Recovery,Transformation and Resilience Plan and by NextGenerationEU from the European Union,and by the María de Maeztu seal of excellence from the Spanish Research Agency(CEX2018-000800-M)Mr.B.Yang wishes to express his gratitude for the support of the China Scholarship Council(202106370122).
文摘A large number of anomalous extension twins,with low or even negative twinning Schmid factors,were found to nucleate and grow in a strongly textured Mg-1Al alloy during tensile deformation along the extruded direction.The deformation mechanisms responsible for this behaviour were investigated through in-situ electron back-scattered diffraction,grain reference orientation deviation,and slip trace-modified lattice rotation.It was found that anomalous extension twins nucleated mainly at the onset of plastic deformation at or near grain boundary triple junctions.They were associated with the severe strain incompatibility between neighbour grains as a result from the differentbasal slip-induced lattice rotations.Moreover,the anomalous twins were able to grow with the applied strain due to the continuous activation ofbasal slip in different neighbour grains,which enhanced the strain incompatibility.These results reveal the complexity of the deformation mechanisms in Mg alloys at the local level when deformed along hard orientations.
基金This research is partly supported by the scholarship from China Scholarship Council under the Grant CSC(201608060071).
文摘High flammability of polymers has become a major issue which has restricted its applications.Recently,highly crystalline materials and metal–organic frameworks(MOFs),which consisted of metal ions and organic linkers,have been intensively employed as novel fire retardants(FRs)for a variety of polymers(MOF/polymer).The MOFs possessed abundant transition metal species,fire-retardant elements and potential carbon source accompanied with the facile tuning of the structure and property,making MOF,its derivatives and MOF hybrids promising for fire retardancy research.The recent progress and strategies to prepare MOF-based FRs are emphasized and summarized.The fire retardancy mechanisms of MOF/polymer composites are explained,which may guide the future design for efficient MOF-based FRs.Finally,the challenges and prospects related to different MOFbased FRs are also discussed and aim to provide a fast and holistic overview,which is beneficial for researchers to quickly get up to speed with the latest development in this field.
基金Natural Science Foundation of China(No.51871244)Hunan Provincial Innovation Foundation for Postgraduate,China(No.CX20200172)Fundamental Research Funds for the Central Universities of Central South University,China(No.1053320190103)。
基金funding from the Madrid region under programme S2018/NMT4381-MAT4.0-CM projectFunding from projects PID2019111285RB-I00 and PID2020-118626RB-I00 awarded by the Spanish Ministry of Science, Innovation and Universitiesfinancial support from the China Scholarship Council (Grant no 201706050154)
文摘This work investigates the effect of solid solution on ductility and on the activation of individual deformation mechanisms at moderate temperatures and at quasi-static strain rates in Mg-Zn and Mg-Al alloys. With that aim, four solid solution Mg-Zn and Mg-Al binary alloy ingots containing 1 and 2 wt.% solute atoms were subjected to hot rolling and subsequent annealing to generate polycrystals with similar average grain size and basal-type texture for each composition. The activity of the different slip systems after tensile testing at 150°C and at 250°C was evaluated in pure Mg and in the alloys by EBSD-assisted slip trace analysis. In addition, segregation of Zn and Al atoms at grain boundaries during the thermo-mechanical processing was characterized by HAADF-STEM and EDX. It was found that while the addition of Al and Zn atoms to pure Mg does not lead to major changes in the mechanical strength at the investigated temperatures, it does enhance ductility significantly, especially at 250℃. Our results show that this increase in ductility cannot be attributed to a higher activation of non-basal systems in the alloys, as reported earlier, as the incidence of non-basal systems is indeed considerably higher in pure Mg. This work suggests, on the contrary, that the ductility increase may be attributed to the presence of a more homogenous basal activity in the alloys due to a lower degree of orientation clustering, to grain boundary solute segregation, and to a higher slip diffusivity at grain interiors.
基金This work was partially supported by the China Scholarship Council under the Grant CSC(201908110272)BIOFIRESAFE Project funded by Ministerio De Ciencia E Innovacion,Spain,with the project numbers:PID2020-117274RB-I00BIOFIRESAFE and PEJ-2018 MINECO.
文摘Early-stage fire-warning systems(EFWSs)have attracted significant attention owing to their superiority in detecting fire situations occurring in the pre-combustion process.Substantial progress on EFWSs has been achieved recently,and they have presented a considerable possibility for more evacuation time to control constant unintentional fire hazards in our daily life.This review mainly makes a comprehensive summary of the current EFWSs,including the working mechanisms and their performance.According to the different working mechanisms,fire alarms can be classified into graphene oxide-based fire alarms,semiconductor-based fire alarms,thermoelectric-based fire alarms,and fire alarms on other working mechanisms.Finally,the challenge and prospect for EFWSs are briefly provided by comparing the art of state of fire alarms.This work can propose a more comprehensive understanding of EFWSs and a guideline for the cutting-edge development direction of EFWSs for readers.
基金financially supported by the IMDEA Materials Institute STRUBAT Project, Spanish Ministry of Economy, Industry, and Competitiveness (MINECO), the Spanish Ministry of Science and Innovation, and Comunidad de Madrid for Juan de la Cierva fellowship (IJCI-2015-25488)the Retos Investigacion Project (MAT2017-84002-C2-2-R)/Ramon y Cajal fellowship (RYC-2018-025893-I)+1 种基金the Talent attraction fellowship (2016-T1/IND-1300)the China Scholarship Council (201706740087)。
文摘Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors,and thus realize both high energy density and power density in a single configuration.Nevertheless,applications of SICs are severely restricted by their insufficient energy densities (<100Wh/kg) resulted from the kinetics imbalance between cathodes and anodes.Herein,we report a nanograin-boundary-rich hierarchical Co_(3)O_(4) nanorod anode composed of~20 nm nanocrystallites.Extreme pseudocapacitance (up to 72%@1.0 mV/s) is achieved through nanograin-boundary-induced pseudocapacitive-type Na^(+) storage process.Co_(3)O_(4) nanorod anode delivers in this case highly reversible capacity (810 mAh/g@0.025 A/g),excellent rate capability (335 mAh/g@5.0 A/g),and improved cycle stability (100 cycles@1.0 A/g with negligible capacity degradation).The outstanding performance can be credited to the hierarchical morphology of Co_(3)O_(4) nanorods and the well-designed nanograinboundaries between nanocrystallites that avoid particle agglomeration,induce pseudocapacitive-type Na^(+) storage,and accommodate volume variation during sodiation-desodiation processes.Nitrogendoping of the Co_(3)O_(4) nanorods not only generates defects for extra surficial Na^(+) storage but also increases the electronic conductivity for efficient charge separation and lowers energy barrier for Na^(+) intercalation.Synergy of conventional reaction mechanism and pseudocapacitive-type Na^(+) storage enables high specific capacity,rapid Na^(+) diffusion,and improved structural stability of the Co_(3)O_(4) nanorod electrode.The SIC integrating this highly pseudocapacitive anode and activated carbon cathode delivers exceptional energy density (175 Wh/kg@40 W/kg),power density (6632 W/kg@37 Wh/kg),cycle life (6000 cycles@1.0 A/g with a capacity retention of 81%),and coulombic efficiency (~100%).
文摘Although in recent years glass fibre reinforced cement (GRC) has been used in buildings and infrastructure, its application in structural elements has been somewhat restricted due to the worsening of its mechanical properties with ageing and the limited data available related with its fracture energy. With the aim of developing existing knowledge of GRC, the fracture energy in an in-plane and out-of-plane direction of the panel has been obtained. Three types of GRC with different formulations have been tested. The results showed that the fracture energy of a GRC with a 25% addition of a pozzolanic admixture is 40% and 8% higher than a standard GRC in, respectively, in-plane and out-of-plane directions. Similarly, an addition of 25% of thermal-treated kaolin to a standard GRC increases its fracture energy up to 490% and 400%, to the corresponding orientation. The use of digital image correlation (DIC) in the fracture test analysis has permitted a description of the damaging patterns and explanation of the behaviours identified in the fracture tests performed. The multi-cracking process that appears explains the higher fracture energy found in the GRC with an addition of 25% of the aforementioned thermal-treated kaolin. The analysis performed by means of DIC and the results obtained showed GRC with an addition of 25% of thermal-treated kaolin to be the most suitable formulation for possible future structural applications with a short life span in horizontal and vertical elements.
基金supported by the project(MAD2D-CM)-IMDEA Materials funded by Comunidad de Madrid and by the Recovery,Transformation and Resilience Plan and by NextGenerationEU from the European Union,and by the María de Maeztu seal of excellence from the Spanish Research Agency(CEX2018-000800-M)B.Y.wishes to express his gratitude for the support of the China Scholarship Council(202106370122).
文摘Twin nucleation in textured Mg alloys was studied by means of electron back-scattered diffraction in samples deformed in tension along different orientations in more than 3000 grains.In addition,28 relevant parameters,categorized in four different groups(loading condition,grain shape,apparent Schmid factors,and grain boundary features)were also recorded for each grain.This information was used to train supervised machine learning classification models to analyze the influence of the microstructural features on the nucleation of extension twins in Mg alloys.It was found twin nucleation is favored in larger grains and in grains with high twinning Schmid factors,but also that twins may form in the grains with very low or even negative Schmid factors for twinning if they have at least one smaller neighboring grain and another one(or the same)that is more rigid.Moreover,twinning of small grains with high twinning Schmid factors is favored if they have low basal slip Schmid factors and have at least one neighboring grain with a high basal slip Schmid factor that will deform easily.These results reveal the role of many-body relationships,such as differences in stiffness and size between a given grain and its neighbors,to assess extension twin nucleation in grains unfavorably oriented for twinning.
基金the young scholars of the National Natural Science Foundation of China(Grant No.5210011609)the National Natural Science Foundation of Hunan Province(Grant No.2021JJ40749)+1 种基金Chenying Shi would like to express the support by China Scholarship Council(No.202006370260)Biaobiao Yang would like to express the support by China Scholarship Council(No.202106370122).
文摘Ti additions in Cu–Cr–Zr alloys are useful for achieving high mechanical properties.In this work,the influence of Ti contents(0.25 wt%,0.6 wt%,and 1.02 wt%)on the microstructure,mechanical,and electrical properties of Cu–Cr–Zr alloys has been investigated experimentally,along with thermodynamic and kinetic calculations.The electrical conductivity decreased but the hardness/strength increased with increasing Ti content.The lower electrical conductivity is due to increased electron scattering through the solution of more Ti atoms in the Cu matrix.As for the higher hardness/strength,it is mainly owing to higher dislocation density and finer FCC-Cr precipitates.Furthermore,a model considering the size distributions of precipitates is adopted to calculate precipitation strengthening quantitatively.The calculated yield strengths are consistent with the experimental ones for the alloys.The thermodynamic and kinetic calculations reveal that increasing Ti content can facilitate the nucleation of FCC-Cr but enhance its activation energy,hence hindering the growth process.The present work study can provide an effective strategy for producing copper alloys with expected performance.
基金financial support of FRIAfinancial support of the European Research Council for a starting grant under grant No. 716678Chinese Scientific Council for financial support (No. 201606890031)
文摘Optimization of the intermetallic layer thickness and the suppression of interfacial defects are key elements to improve the load bearing capacity of dissimilar joints. However, till date we do not have a systematic tool to investigate the dissimilar joints and the intermetallic properties produced by a welding condition. Friction Melt Bonding (FMB) is a recently developed technique for joining dissimilar metals that also does not exempt to these challenges. The FMB of DP980 and A16061-T6 was investigated using a new physical simulation tool, based on Gleeble thermo-mechanical simulator, to understand the effect of individual parameter on the intermetallic formation. The proposed method demonstrates its capability in reproducing the intermetallic characteristics, including the thickness of intermetallic bonding layer, the morphology and texture of its constituents (Fe2AU and Fe4Ali3), as well as their nanohardness and reduced modulus. The advantages of physical simulation tool can enable novel developing routes for the development of dissimilar metal joining processes and facilitate to reach the requiring load bearing capacity of the joints.
