Rejuvenation,bringing metallic glasses(MGs)to the younger and higher energy states,provides an alternative avenue to explore the interplay between the property and microstructures of MGs.In this study,the creep behavi...Rejuvenation,bringing metallic glasses(MGs)to the younger and higher energy states,provides an alternative avenue to explore the interplay between the property and microstructures of MGs.In this study,the creep behavior of the Zr_(69.5)Cu_(12)Ni_(11)Al_(7.5)MGs was experimentally examined by controlling the energy state in terms of structural rejuvenation and thermal annealing.It is found that compared to the as-cast counterpart,the annealed MG at a lower energy state exhibits a higher hardness,a smaller displacement,and a lower creep rate due to the decreased free volume and the inhibited activation of the shear transformation zone.Conversely,the rejuvenated MG at a high energy state displays lower hardness and increased free volume content,yet it demonstrates superior creep resistance compared to its as-cast counterpart,which deviates from conventional understanding.This unexpected phenomenon occurs as the initial high-content free volume annihilates during creep,and strain hardening takes precedence over strain softening as the prevailing process during creep deformation,leading to a superior creep performance in extremely rejuvenated MGs.展开更多
The energy state and atomic level structure of metallic glasses(MGs)are very sensitive to their cooling rates,and a lower cooling rate generally causes a lower energy and more relaxed state of MGs.In this work,the Zr4...The energy state and atomic level structure of metallic glasses(MGs)are very sensitive to their cooling rates,and a lower cooling rate generally causes a lower energy and more relaxed state of MGs.In this work,the Zr41.2 Ti13.8 Cu12.5 Ni10 Be22.5(Vit.1)ribbons with a thickness of 40μm and 110μm and the strips with a thickness of 320μm and 490μm were produced by single-roll melt spinning and twin-roll casting,respectively.The increase in thickness of either ribbons or strips results in a lower energy state with a smaller relaxation enthalpy,a lower content of free volume,and a higher hardness.Although the cooling rate of the twin-roll produced 320μm-thick strip is almost one magnitude lower than that of the single-roll produced 110μm-thick ribbon,the former,however,possesses a rejuvenated energy state as compared to the latter.Molecular dynamics simulations reveal that the squeezing force during twin-roll casting affects the evolution of connection types of clusters,and the 2-atom and 4-atom connections are prone to be retained,which results in a higher energy state of MGs.Such a rejuvenation process during twin-roll casting can overwhelm the relaxation process caused by the lower cooling rate.Therefore,twin-roll casting is not only a method being capable for producing strips with a large thickness,but also prone to obtain a high energy state of the MG strip.展开更多
A β-Ti dendrite reinforced Zr-based bulk metallic glass composite(BMGC) was found to be brittle when cast in a large size. The reasons for the embrittlement and the effectiveness of the cryothermal cycling(CTC) treat...A β-Ti dendrite reinforced Zr-based bulk metallic glass composite(BMGC) was found to be brittle when cast in a large size. The reasons for the embrittlement and the effectiveness of the cryothermal cycling(CTC) treatment in restoring the mode I fracture toughness are examined. Plasticity in all the CTC treated BMGC is estimated from the distribution and occurrence of pop-ins in nanoindentation tests and by measuring the magnitude of enthalpy of relaxation(△H_(rel)) via differential scanning calorimetry(DSC). This is further validated by examining the strain-to-failure(ε_(f)) in compression tests. Mode I fracture behaviour of the as-cast embrittled BMGC and the CTC treated BMGC, which exhibits maximum plasticity, is examined. Results show that both BMGCs are equally brittle and exhibit 5 times lower notch toughness(K_(QJ))than their tougher counterpart. Post-facto imaging of the side surfaces reveals the absence of notch-tip plasticity in both BMGCs. The lack of notch tip plasticity of CTC treated BMGC, despite exhibiting signatures of plasticity in nanoindentation and higher △Hrelis rationalized by reassessing the origin of pop-ins in nanoindentation tests and describing the variations in chemical and topological short range ordering during CTC, respectively. Implications of these results in terms of improving the fracture toughness of structurally relaxed BMGCs via CTC are discussed.展开更多
Asphalt binder plays a significant role in the performance of asphalt pavement.However,due to the limited availability of crude oil and the increasing cost of asphalt,alternatives are being investigated.Reclaimed asph...Asphalt binder plays a significant role in the performance of asphalt pavement.However,due to the limited availability of crude oil and the increasing cost of asphalt,alternatives are being investigated.Reclaimed asphalt pavement(RAP)provides a sustainable solution for the increasing demand of asphalt.However,the amount of RAP which can be utilized in asphalt mixtures is limited due to production and performance issues.Incorporation of high RAP content calls for rejuvenators,which rejuvenate the aged binder and increases the degree of blending.Among various rejuvenators,waste cooking oil(WCO)is gaining increased attention due to its availability and concern towards environmental pollution.When combined in proper proportions with RAP,WCO is a potential rejuvenator,which restores the properties of aged binder to that of unaged asphalt binder.This addresses two problems simultaneously and can greatly benefit the economy and environment.This study focuses on the viscoelastic and rheological properties of the rejuvenated binder with WCO and RAP.The rheological properties are evaluated using frequency sweep test by assessing the complex shear modulus and rutting parameter of different binders.The vis-coelastic properties are studied using multiple stress creep recovery(MSCR)test.The data of the MSCR test are analyzed with the Burger model to understand the viscoelastic prop-erties of the rejuvenated RAP binder.For each of 75%,60%,and 45%RAP,three different oil proportions are selected,and the optimum WCO content is identified.The study concludes that higher RAP content results in lower viscous strain and higher elastic strain,whereas after mixing higher WCO,the viscous strain increases,and the elastic strain decreases.Hence,it is crucial to mix WCO and RAP in the optimum ratio to obtain the desired rheo-logical and viscoelastic properties.展开更多
Hot recycling of reclaimed asphalt pavement(RAP)from replacement of deteriorated asphalt pavements is a widespread technique,and able to ensure clear economic and environmental benefits.For this reason,paving industri...Hot recycling of reclaimed asphalt pavement(RAP)from replacement of deteriorated asphalt pavements is a widespread technique,and able to ensure clear economic and environmental benefits.For this reason,paving industries,agencies and researchers are spending significant efforts in order to maximize such advantages by increasing the amount of RAP within new asphalt mixtures.Nevertheless,adequate performance of recycled mixtures must be guaranteed despite the re-use of high amounts of RAP which involves the presence of aged,oxidized and stiffened binder.In this perspective,the present study aimed at evaluating the rheological properties at mid-service and high-service temperatures of bituminous blends composed by 40%of virgin binder and 60%of aged rejuvenated bitumen(simulating the aged hard bitumen coming from the RAP).Such proportion was selected to represent a high recycling rate of RAP(about 60%of the total weight of aggregates,RAP included).A chemical commercial additive at the liquid state was selected as rejuvenator;it was dosed at the optimum content based on empirical and rheological preliminary characterization.The performance of the recycled blend was then compared to that of a virgin reference bitumen.Dynamic shear rheometer tests were carried out to determine the master curves and the failure characteristics(at mid and high service temperatures)of the selected binders.The effect of aging(related to the durability over the material lifetime)was also studied analyzing binders’responses in unaged,shortterm and long-term aged conditions.Overall,experimental findings demonstrated the efficacy of the rejuvenation of recycled binders containing very high amount of aged bitumen.展开更多
Presently,there is a necessity of increasing the reclaimed asphalt pavement(RAP)content in recycling of asphalt pavements to save material cost,preserve energy and protect the environment and efforts are being made to...Presently,there is a necessity of increasing the reclaimed asphalt pavement(RAP)content in recycling of asphalt pavements to save material cost,preserve energy and protect the environment and efforts are being made to utilize 100%RAP in the mixes.RAP binder is usually stiff due to oxidation and loss of volatiles.So addition of high amount of RAP to the asphalt mix,may make it prone to fatigue failure.Due to this reason,rejuvenators are added to restore some of the physical and chemical properties for desired performance of the mixture.In this study,a locally available non-edible oil known as Polanga oil(biological name:Calophyllum inophyllum)has been explored as rejuvenator to study its effect on performance of the aged binders.Aged binder prepared in the laboratory using the Pressure Aging Vessel(PAV)and binder extracted from the RAP collected from a nearby source were used in this study for rejuvenation.Aged binder and RAP binder mixed with the rejuvenator at varying percentages.The rheological characterizations in terms of flow,rutting,fatigue and creep recovery of rejuvenated PAV aged&RAP binders were carried out using a dynamic shear rheometer(DSR)to determine the optimum dosage of the rejuvenator.It was observed that,5 percent of Polanga oil is able to divulge the desirable rheological properties of the rejuvenated binder.展开更多
The objective of this paper is to comprehensively review the research progress of bio-oil properties and hot rejuvenation behavior and mechanism to aged asphalt.The preparation process,composition characteristics of b...The objective of this paper is to comprehensively review the research progress of bio-oil properties and hot rejuvenation behavior and mechanism to aged asphalt.The preparation process,composition characteristics of bio-oils and their component correspondence with petroleum asphalt were compared.The diffusion and fusion effects of various bio-oils in aged asphalt were introduced.Bio-oil cannot be used as a direct alternative of petroleum asphalt,but it has the potential to effectively rejuvenate aged asphalt binders due to the component similarity with petroleum asphalt and good diffusion properties.For the asphalt rejuvenation,the functionalization treatment methods of bio-oil were discussed such as purification,composition modification and component conversion.The active groups and derivatives in bio-oil can be converted into the missing components of the aged binder through phenolate,grafting,polycondensation,resinifying,but the conversion process and mechanism are still unclear.From the perspectives of diffusion behavior,components regulation,dissolving asphaltene and micro-rejuvenation effect,the rejuvenation behavior and mechanism of bio-oil on aged asphalt were elaborated,and the effects of various types of bio-oil and aged asphalt on rejuvenation behavior were analyzed.The preparation process and dosage of bio-rejuvenator were summarized.The rejuvenation effects of bio-oil on aged asphalt were comprehensively investigated from the aspects of high and low temperature performances,rheological properties,microstructure and chemical composition of bio-rejuvenated asphalt binders.Finally,the limitations of bio-oil used as asphalt rejuvenators were discussed,and future research directions were prospected,which can provide reference and theoretical basis for the development of high-performance bio-oil rejuvenating agents and the engineering application of bio-oil to improve the properties of aged asphalt materials.展开更多
Recent attention has been directed towards tailoring the internal structure and enhancing the plasticity of metallic glasses(MGs)via rejuvenation treatments.This work aims to comprehensively review the various approac...Recent attention has been directed towards tailoring the internal structure and enhancing the plasticity of metallic glasses(MGs)via rejuvenation treatments.This work aims to comprehensively review the various approaches and underlying mechanisms of inducing rejuvenation in MGs,including thermal-activated methods for deep-cooling cycling treatments and annealing-induced regeneration,mechanical-driven methods of pre-elastic loading and plastic deformation,thermo-mechanically coupled methods for thermo-mechanical creep and thermoplastic forming,and irradiation-induced rejuvenation.Additionally,strategies such as gradient rejuvenation for promoting a favorable distribution of free volume gradients to deflect shear bands are discussed for enhancing plasticity.Finally,the review delves into the challenges and prospects associated with advancing the development of MGs exhibiting high plasticity at ambient conditions.This review is anticipated to contribute to fostering a systematic understanding of the diverse methods and mechanisms employed to enhance the plasticity of MGs via rejuvenation treatments.展开更多
Aging,as an inherent stage of life processes,has always been a core research focus in life sciences.Current studies confirm that the accumulation of intracellular molecular damage is a key driver of aging.As protectiv...Aging,as an inherent stage of life processes,has always been a core research focus in life sciences.Current studies confirm that the accumulation of intracellular molecular damage is a key driver of aging.As protective structures at chromosome ends,telomeres exhibit direct correlations between their length and stability and cellular aging processes,disease risks,and lifespan.This article systematically reviews the structural functions of telomeres and their relationship with aging,with particular emphasis on telomere rejuvenation strategies based on electromagnetic radiation techniques.Key experimental approaches include Gavich's mitotic radiation,Composite Wave Resonator(CWRT),and modern telomere length intervention trials.By synthesizing the latest domestic and international research findings,this paper analyzes the feasibility and limitations of these technologies while exploring their potential applications in anti-aging research,providing theoretical references for future studies.展开更多
Technological advancements have produced sustainable approaches to pavement preservation and reconstruction procedures.Specific recycling processes are being developed to reuse the asphalt concrete guaranteeing costs ...Technological advancements have produced sustainable approaches to pavement preservation and reconstruction procedures.Specific recycling processes are being developed to reuse the asphalt concrete guaranteeing costs and environmental effects reduction.Reclaimed asphalt pavement(RAP)is the material worldwide used in the road construction sector to ensure the sustainability of asphalt pavement.RAP employment percentages in asphalt concrete layers are increasing.The development of cold mix asphalt(CMA)recycling technique including high amount of RAP is becoming popular especially for localized patching and potholes.Wearing course layers designed for bicycle lanes realized with 100%RAP and CMA technologies are presented in this research.Two cycle paths rehabilitated with different construction technologies in-plant and in-place recycling techniques are compared by performing a trial field and laboratory analysis on compacted and cored samples.An innovative rejuvenator used as additive specifically designed for CMAs is added as rejuvenator in both RAPs.The main goal is to determine the frictional,physical and mechanical characteristics of solutions produced by using high quantity of recycled materials.British pendulum tester(BPT)and Micro GripTester are applied to assess skid performance and indirect tensile strength test(ITS)and Marshall stability is performed to analyse the mechanical behaviour.RAPs skid resistance and physical-mechanical properties provide positive outcomes with viable characteristics for urban soft-mobility solutions.The innovative machine used in the in-place technique demonstrated excellent performance in terms of milling and mixing,representing a valid alternative for repaving applications in the urban context.展开更多
Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore it...Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore its creep properties.In this work,a series of RHT experiments were carried out on a directionally solidified(DS)nickel-based superalloy under different solution temperatures and primary aging temperatures based on the standard heat treatment(SHT)process parameters to investigate the mechanism of temperature influence on DS's microstructure after RHT.It is indicated that a more uniform microstructure can be obtained under higher solution temperatures and lower primary aging temperatures compared to the SHT process.Furthermore,by employing the image processing methods to quantify microstructural parameters,a comprehensive indicator parameter for the RHT effect(marked as Prej)was proposed to characterize the effects of RHT on DS superalloy's microstructure and creep property combined with the entropy weight method.Based on this,a regression model to describe the relationship between RHT process parameters and Prej was constructed by using the response surface methodology(RSM).It is revealed that the optimal solution temperature and primary aging temperature for this DS superalloy are 1283°C and 1095°C,respectively.Then the conclusion was validated through complete creep experiments on the DS superalloy,which showed the creep life after RHT reaches 95.5%of the SHT specimen,and the total life has increased by 20.6%.展开更多
We Built Railways on the Roof of the World Author:Wang Quanquan Paperback,155 pages Published by Foreign Languages Press The jade-green Fuxing(rejuvenation)bullet train,snow white hada(prayer scarves),and beaming face...We Built Railways on the Roof of the World Author:Wang Quanquan Paperback,155 pages Published by Foreign Languages Press The jade-green Fuxing(rejuvenation)bullet train,snow white hada(prayer scarves),and beaming faces keep flashing into the photographer’s lens.展开更多
The utilization of reclaimed asphalt pavement(RAP)in asphalt mixtures has gained momentum in recent years,yet concerns persist regarding the long-term performance and binder properties of high RAP content mixtures.To ...The utilization of reclaimed asphalt pavement(RAP)in asphalt mixtures has gained momentum in recent years,yet concerns persist regarding the long-term performance and binder properties of high RAP content mixtures.To overcome these challenges,rejuvenators have emerged as a promising solution to enhance the properties of aged asphalt binders and improve the overall performance of asphalt mixtures.This paper provides a comprehensive state-of-the-art review of rejuvenator technology and its potential to enhance the performance and sustainability of asphalt pavements.Rejuvenators are additives used to restore the properties of aged asphalt binders,particularly when incorporating high percentages of RAP.The performance of these additives varies based on their origin,and different methods can be used to analyze the rejuvenation process.Since proper specifications for rejuvenators are not available,blending charts are used to determine the optimum dosage of rejuvenators.However,proper blending must be achieved to maximize results and reduce the effect of black rock.Laboratory tests and some field performance studies on rejuvenated aged asphalt binders and RAP mixtures have shown improved or similar performance compared to virgin materials.Additionally,the use of rejuvenators has been observed to reduce construction costs,suggesting that this is a cost-effective technology for asphalt pavements.While rejuvenators show promise in improving the performance of pavements with recycled materials,challenges remain regarding optimization,long-term durability,and environmental effects.This review paper also identifies key areas for future research,including life-cycle cost analyses,comprehensive environmental impact assessments,and long-term field performance monitoring.展开更多
Annealing has been a popular method to improve the soft magnetism of metallic glasses (MGs), which however usually makes MGs brittle and difficult to process. Here, it is demonstrated that the embrittled Fe-based MG c...Annealing has been a popular method to improve the soft magnetism of metallic glasses (MGs), which however usually makes MGs brittle and difficult to process. Here, it is demonstrated that the embrittled Fe-based MG can be reductilized and the coercivity can be further lowered through the rejuvenation of memory effect. The synchronous improvement in the plasticity and soft magnetic properties is attributed to the combination effects of releasing much residual stress, decreasing the magnetic anisotropy, and homogenizing the glasses during the rejuvenation process. The current work opens a new perspective to improve the properties of MGs by utilizing the memory effect and holds promising commercial application potential.展开更多
The effects of rejuvenation heat treatment(RHT)on the serrated flow behavior and fracture mode of nickel-based superalloys(R26)were investigated by tensile tests and microstructural characterization.The serrated flow ...The effects of rejuvenation heat treatment(RHT)on the serrated flow behavior and fracture mode of nickel-based superalloys(R26)were investigated by tensile tests and microstructural characterization.The serrated flow activation energies were determined to be 41−72 and 64−81 kJ/mol before and after RHT,respectively.Dynamic strain aging in the alloy is caused by the diffusion of carbon atoms into dislocation channels in the nickel matrix.Before RHT,carbides are concentrated at the grain boundaries.Cracks initiate from these carbides and propagate along the grain boundaries.RHT dissolves carbides at grain boundaries,transferring crack initiation to the precipitated phase group in the grains.RHT increases carbon atom concentration in the nickel matrix,enhancing dynamic strain aging and serrated flow behavior.展开更多
“Transformation is not simply about shutting down;it is more about eliminating outdated production capacity while nurturing new driving forces,”according to Wan Qian,a member of the Standing Committee of the Xiangxi...“Transformation is not simply about shutting down;it is more about eliminating outdated production capacity while nurturing new driving forces,”according to Wan Qian,a member of the Standing Committee of the Xiangxiang Municipal Party Committee,referring to an eco-friendly chemical industrial park in Xiangxiang City,central China’s Hunan Province.展开更多
The effects of deep cryogenic-cycling treatment(DCT)on the mechanical properties,soft magnetic properties,and atomic scale structure of the Fe_(73.5)Si_(13.5)B_(9)Nb_(3)Cu_(1)amorphous nanocrystalline alloy were inves...The effects of deep cryogenic-cycling treatment(DCT)on the mechanical properties,soft magnetic properties,and atomic scale structure of the Fe_(73.5)Si_(13.5)B_(9)Nb_(3)Cu_(1)amorphous nanocrystalline alloy were investigated.The DCT samples were obtained by subjecting the as-annealed samples to a thermal cycling process between the temperature of the supercooled liquid zone and the temperature of liquid nitrogen.Through flat plate bending testing,hardness measurements,and nanoindentation experiment,it is found that the bending toughness of the DCT samples is improved and the soft magnetic properties are also slightly enhanced.These are attributed to the rejuvenation behavior of the DCT samples,which demonstrate a higher enthalpy of relaxation.Therefore,DCT is an effective method to enhance the bending toughness of Fe-based amorphous nanocrystalline alloys without degrading the soft magnetic properties.展开更多
With socialism with Chinese characteristics entering into a new era,the great rejuvenation of the Chinese nation is now on an irreversible course.China has come ever closer to the center stage of the world.Grasping th...With socialism with Chinese characteristics entering into a new era,the great rejuvenation of the Chinese nation is now on an irreversible course.China has come ever closer to the center stage of the world.Grasping the international landscape,the pulse of the times,the trends of the world,and with the progress of human development in mind,General Secretary Xi Jinping has put forward a series of original diplomatic concepts and major initiatives,creating the Xi Jinping Thought on Diplomacy.展开更多
The history and practice of the great rejuvenation of the Chinese nation show that the founding of the Communist Party of China(CPC)has opened up a new era in the Chinese history and the CPC constitutes the fundamenta...The history and practice of the great rejuvenation of the Chinese nation show that the founding of the Communist Party of China(CPC)has opened up a new era in the Chinese history and the CPC constitutes the fundamental leadership and organizational guarantee for the realization of the great rejuvenation of the Chinese nation.The CPC has united and led the Chinese people in having founded the People’s Republic of China(PRC),in having established the basic socialist system,in having eliminated all exploitation systems,and in having laid the fundamental political premise and institutional foundation for the great rejuvenation of the Chinese nation.The CPC has also led the Chinese people in having carried out Reform and Opening-up,in having launched the road of socialism with Chinese characteristics,and in having realized the great leap of the Chinese nation from standing up to becoming rich.Since its 18th National Congress,standing at the historical starting point of the new era,the CPC has led the people in unremitting struggle,has opened up a new realm of socialism with Chinese characteristics in the new era,and has achieved a historical breakthrough for the Chinese nation from becoming rich to becoming strong.The course of the CPC leading the Chinese people to realize the great rejuvenation of the Chinese nation reflects the systematic thinking of economic development and the integrated utilization of Marxist theory of economic development and traditional theories of economic development.The history of the CPC uniting and leading the people to strive for the great rejuvenation of the Chinese nation enlightens us that the CPC,as the“visible hand”of the cause of socialism with Chinese characteristics,is the fundamental guarantee for the great rejuvenation of the Chinese nation,and China must adhere to the CPC’s leadership.展开更多
基金the National Natural Science Foundation of China(Nos.52022100,51871217,52001075,and 51971097)J.P.is also grateful for support from the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2020194)Y.Lin thanks the China Postdoctoral Science Foundation(No.2021M701290).
文摘Rejuvenation,bringing metallic glasses(MGs)to the younger and higher energy states,provides an alternative avenue to explore the interplay between the property and microstructures of MGs.In this study,the creep behavior of the Zr_(69.5)Cu_(12)Ni_(11)Al_(7.5)MGs was experimentally examined by controlling the energy state in terms of structural rejuvenation and thermal annealing.It is found that compared to the as-cast counterpart,the annealed MG at a lower energy state exhibits a higher hardness,a smaller displacement,and a lower creep rate due to the decreased free volume and the inhibited activation of the shear transformation zone.Conversely,the rejuvenated MG at a high energy state displays lower hardness and increased free volume content,yet it demonstrates superior creep resistance compared to its as-cast counterpart,which deviates from conventional understanding.This unexpected phenomenon occurs as the initial high-content free volume annihilates during creep,and strain hardening takes precedence over strain softening as the prevailing process during creep deformation,leading to a superior creep performance in extremely rejuvenated MGs.
基金supported financially by the National Natural Science Foundation of China(Nos.51790484,51701213 and 51801174)the National Key Research and Development Program of China(No.2018YFB0703402)+2 种基金the Liaoning Revitalization Talents Program(Nos.XLYC1802078,XLYC1807062)the China Postdoctoral Science Foundation(No.2018M633005)the Dongguan Innovative Research Team Program(No.2014607134).
文摘The energy state and atomic level structure of metallic glasses(MGs)are very sensitive to their cooling rates,and a lower cooling rate generally causes a lower energy and more relaxed state of MGs.In this work,the Zr41.2 Ti13.8 Cu12.5 Ni10 Be22.5(Vit.1)ribbons with a thickness of 40μm and 110μm and the strips with a thickness of 320μm and 490μm were produced by single-roll melt spinning and twin-roll casting,respectively.The increase in thickness of either ribbons or strips results in a lower energy state with a smaller relaxation enthalpy,a lower content of free volume,and a higher hardness.Although the cooling rate of the twin-roll produced 320μm-thick strip is almost one magnitude lower than that of the single-roll produced 110μm-thick ribbon,the former,however,possesses a rejuvenated energy state as compared to the latter.Molecular dynamics simulations reveal that the squeezing force during twin-roll casting affects the evolution of connection types of clusters,and the 2-atom and 4-atom connections are prone to be retained,which results in a higher energy state of MGs.Such a rejuvenation process during twin-roll casting can overwhelm the relaxation process caused by the lower cooling rate.Therefore,twin-roll casting is not only a method being capable for producing strips with a large thickness,but also prone to obtain a high energy state of the MG strip.
基金supported through the Start-up research grant (No.SRG/2020/000095) of Science and Engineering Research Board,DST,Go INanyang Technological University was supported by the funding from A*STAR via the Structural Metals and Alloys Programme (No.A18B1b0061)+2 种基金Institute of Metal Research CAS was supported by the National Natural Science Foundation of China (Nos.52171164 and 51790484)the National Key Research and Development Program (No.2018YFB0703402)the Youth Innovation Promotion Association CAS (No.2021188)。
文摘A β-Ti dendrite reinforced Zr-based bulk metallic glass composite(BMGC) was found to be brittle when cast in a large size. The reasons for the embrittlement and the effectiveness of the cryothermal cycling(CTC) treatment in restoring the mode I fracture toughness are examined. Plasticity in all the CTC treated BMGC is estimated from the distribution and occurrence of pop-ins in nanoindentation tests and by measuring the magnitude of enthalpy of relaxation(△H_(rel)) via differential scanning calorimetry(DSC). This is further validated by examining the strain-to-failure(ε_(f)) in compression tests. Mode I fracture behaviour of the as-cast embrittled BMGC and the CTC treated BMGC, which exhibits maximum plasticity, is examined. Results show that both BMGCs are equally brittle and exhibit 5 times lower notch toughness(K_(QJ))than their tougher counterpart. Post-facto imaging of the side surfaces reveals the absence of notch-tip plasticity in both BMGCs. The lack of notch tip plasticity of CTC treated BMGC, despite exhibiting signatures of plasticity in nanoindentation and higher △Hrelis rationalized by reassessing the origin of pop-ins in nanoindentation tests and describing the variations in chemical and topological short range ordering during CTC, respectively. Implications of these results in terms of improving the fracture toughness of structurally relaxed BMGCs via CTC are discussed.
文摘Asphalt binder plays a significant role in the performance of asphalt pavement.However,due to the limited availability of crude oil and the increasing cost of asphalt,alternatives are being investigated.Reclaimed asphalt pavement(RAP)provides a sustainable solution for the increasing demand of asphalt.However,the amount of RAP which can be utilized in asphalt mixtures is limited due to production and performance issues.Incorporation of high RAP content calls for rejuvenators,which rejuvenate the aged binder and increases the degree of blending.Among various rejuvenators,waste cooking oil(WCO)is gaining increased attention due to its availability and concern towards environmental pollution.When combined in proper proportions with RAP,WCO is a potential rejuvenator,which restores the properties of aged binder to that of unaged asphalt binder.This addresses two problems simultaneously and can greatly benefit the economy and environment.This study focuses on the viscoelastic and rheological properties of the rejuvenated binder with WCO and RAP.The rheological properties are evaluated using frequency sweep test by assessing the complex shear modulus and rutting parameter of different binders.The vis-coelastic properties are studied using multiple stress creep recovery(MSCR)test.The data of the MSCR test are analyzed with the Burger model to understand the viscoelastic prop-erties of the rejuvenated RAP binder.For each of 75%,60%,and 45%RAP,three different oil proportions are selected,and the optimum WCO content is identified.The study concludes that higher RAP content results in lower viscous strain and higher elastic strain,whereas after mixing higher WCO,the viscous strain increases,and the elastic strain decreases.Hence,it is crucial to mix WCO and RAP in the optimum ratio to obtain the desired rheo-logical and viscoelastic properties.
基金funded by the Department of Civil,Environmental and Architectural Engineering(ICEA)of the University of Padova(project BIRD182754)。
文摘Hot recycling of reclaimed asphalt pavement(RAP)from replacement of deteriorated asphalt pavements is a widespread technique,and able to ensure clear economic and environmental benefits.For this reason,paving industries,agencies and researchers are spending significant efforts in order to maximize such advantages by increasing the amount of RAP within new asphalt mixtures.Nevertheless,adequate performance of recycled mixtures must be guaranteed despite the re-use of high amounts of RAP which involves the presence of aged,oxidized and stiffened binder.In this perspective,the present study aimed at evaluating the rheological properties at mid-service and high-service temperatures of bituminous blends composed by 40%of virgin binder and 60%of aged rejuvenated bitumen(simulating the aged hard bitumen coming from the RAP).Such proportion was selected to represent a high recycling rate of RAP(about 60%of the total weight of aggregates,RAP included).A chemical commercial additive at the liquid state was selected as rejuvenator;it was dosed at the optimum content based on empirical and rheological preliminary characterization.The performance of the recycled blend was then compared to that of a virgin reference bitumen.Dynamic shear rheometer tests were carried out to determine the master curves and the failure characteristics(at mid and high service temperatures)of the selected binders.The effect of aging(related to the durability over the material lifetime)was also studied analyzing binders’responses in unaged,shortterm and long-term aged conditions.Overall,experimental findings demonstrated the efficacy of the rejuvenation of recycled binders containing very high amount of aged bitumen.
文摘Presently,there is a necessity of increasing the reclaimed asphalt pavement(RAP)content in recycling of asphalt pavements to save material cost,preserve energy and protect the environment and efforts are being made to utilize 100%RAP in the mixes.RAP binder is usually stiff due to oxidation and loss of volatiles.So addition of high amount of RAP to the asphalt mix,may make it prone to fatigue failure.Due to this reason,rejuvenators are added to restore some of the physical and chemical properties for desired performance of the mixture.In this study,a locally available non-edible oil known as Polanga oil(biological name:Calophyllum inophyllum)has been explored as rejuvenator to study its effect on performance of the aged binders.Aged binder prepared in the laboratory using the Pressure Aging Vessel(PAV)and binder extracted from the RAP collected from a nearby source were used in this study for rejuvenation.Aged binder and RAP binder mixed with the rejuvenator at varying percentages.The rheological characterizations in terms of flow,rutting,fatigue and creep recovery of rejuvenated PAV aged&RAP binders were carried out using a dynamic shear rheometer(DSR)to determine the optimum dosage of the rejuvenator.It was observed that,5 percent of Polanga oil is able to divulge the desirable rheological properties of the rejuvenated binder.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52378432 and 52278426)the Key Research and Development Program of Shaanxi Province(Grant No.2022SF-169).
文摘The objective of this paper is to comprehensively review the research progress of bio-oil properties and hot rejuvenation behavior and mechanism to aged asphalt.The preparation process,composition characteristics of bio-oils and their component correspondence with petroleum asphalt were compared.The diffusion and fusion effects of various bio-oils in aged asphalt were introduced.Bio-oil cannot be used as a direct alternative of petroleum asphalt,but it has the potential to effectively rejuvenate aged asphalt binders due to the component similarity with petroleum asphalt and good diffusion properties.For the asphalt rejuvenation,the functionalization treatment methods of bio-oil were discussed such as purification,composition modification and component conversion.The active groups and derivatives in bio-oil can be converted into the missing components of the aged binder through phenolate,grafting,polycondensation,resinifying,but the conversion process and mechanism are still unclear.From the perspectives of diffusion behavior,components regulation,dissolving asphaltene and micro-rejuvenation effect,the rejuvenation behavior and mechanism of bio-oil on aged asphalt were elaborated,and the effects of various types of bio-oil and aged asphalt on rejuvenation behavior were analyzed.The preparation process and dosage of bio-rejuvenator were summarized.The rejuvenation effects of bio-oil on aged asphalt were comprehensively investigated from the aspects of high and low temperature performances,rheological properties,microstructure and chemical composition of bio-rejuvenated asphalt binders.Finally,the limitations of bio-oil used as asphalt rejuvenators were discussed,and future research directions were prospected,which can provide reference and theoretical basis for the development of high-performance bio-oil rejuvenating agents and the engineering application of bio-oil to improve the properties of aged asphalt materials.
基金funding support from the National Natural Science Foundation of China(Nos.51301078,51361017,51461026,51861016,52061021)the European Research Council(Nos.ERC-2013-ADG-340025,ERC-2019-PoC-862485)the Austrian Science Fund(No.I3937-N36).
文摘Recent attention has been directed towards tailoring the internal structure and enhancing the plasticity of metallic glasses(MGs)via rejuvenation treatments.This work aims to comprehensively review the various approaches and underlying mechanisms of inducing rejuvenation in MGs,including thermal-activated methods for deep-cooling cycling treatments and annealing-induced regeneration,mechanical-driven methods of pre-elastic loading and plastic deformation,thermo-mechanically coupled methods for thermo-mechanical creep and thermoplastic forming,and irradiation-induced rejuvenation.Additionally,strategies such as gradient rejuvenation for promoting a favorable distribution of free volume gradients to deflect shear bands are discussed for enhancing plasticity.Finally,the review delves into the challenges and prospects associated with advancing the development of MGs exhibiting high plasticity at ambient conditions.This review is anticipated to contribute to fostering a systematic understanding of the diverse methods and mechanisms employed to enhance the plasticity of MGs via rejuvenation treatments.
文摘Aging,as an inherent stage of life processes,has always been a core research focus in life sciences.Current studies confirm that the accumulation of intracellular molecular damage is a key driver of aging.As protective structures at chromosome ends,telomeres exhibit direct correlations between their length and stability and cellular aging processes,disease risks,and lifespan.This article systematically reviews the structural functions of telomeres and their relationship with aging,with particular emphasis on telomere rejuvenation strategies based on electromagnetic radiation techniques.Key experimental approaches include Gavich's mitotic radiation,Composite Wave Resonator(CWRT),and modern telomere length intervention trials.By synthesizing the latest domestic and international research findings,this paper analyzes the feasibility and limitations of these technologies while exploring their potential applications in anti-aging research,providing theoretical references for future studies.
文摘Technological advancements have produced sustainable approaches to pavement preservation and reconstruction procedures.Specific recycling processes are being developed to reuse the asphalt concrete guaranteeing costs and environmental effects reduction.Reclaimed asphalt pavement(RAP)is the material worldwide used in the road construction sector to ensure the sustainability of asphalt pavement.RAP employment percentages in asphalt concrete layers are increasing.The development of cold mix asphalt(CMA)recycling technique including high amount of RAP is becoming popular especially for localized patching and potholes.Wearing course layers designed for bicycle lanes realized with 100%RAP and CMA technologies are presented in this research.Two cycle paths rehabilitated with different construction technologies in-plant and in-place recycling techniques are compared by performing a trial field and laboratory analysis on compacted and cored samples.An innovative rejuvenator used as additive specifically designed for CMAs is added as rejuvenator in both RAPs.The main goal is to determine the frictional,physical and mechanical characteristics of solutions produced by using high quantity of recycled materials.British pendulum tester(BPT)and Micro GripTester are applied to assess skid performance and indirect tensile strength test(ITS)and Marshall stability is performed to analyse the mechanical behaviour.RAPs skid resistance and physical-mechanical properties provide positive outcomes with viable characteristics for urban soft-mobility solutions.The innovative machine used in the in-place technique demonstrated excellent performance in terms of milling and mixing,representing a valid alternative for repaving applications in the urban context.
基金Supported by National Natural Science Foundation of China(Grant No.52275142)Science Center for Gas Turbine Project(Grant Nos.P2022-AIII-003-001,P2022-B-III-005-001)+1 种基金National Science and Technology Major Project(Grant Nos.J2019-IV-0009-0077,Y2022-IV-0002-0019,J2019-IV-0008-0076)National Basic Scientific Research Project(Grant No.JCKY2021601B204)。
文摘Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore its creep properties.In this work,a series of RHT experiments were carried out on a directionally solidified(DS)nickel-based superalloy under different solution temperatures and primary aging temperatures based on the standard heat treatment(SHT)process parameters to investigate the mechanism of temperature influence on DS's microstructure after RHT.It is indicated that a more uniform microstructure can be obtained under higher solution temperatures and lower primary aging temperatures compared to the SHT process.Furthermore,by employing the image processing methods to quantify microstructural parameters,a comprehensive indicator parameter for the RHT effect(marked as Prej)was proposed to characterize the effects of RHT on DS superalloy's microstructure and creep property combined with the entropy weight method.Based on this,a regression model to describe the relationship between RHT process parameters and Prej was constructed by using the response surface methodology(RSM).It is revealed that the optimal solution temperature and primary aging temperature for this DS superalloy are 1283°C and 1095°C,respectively.Then the conclusion was validated through complete creep experiments on the DS superalloy,which showed the creep life after RHT reaches 95.5%of the SHT specimen,and the total life has increased by 20.6%.
文摘We Built Railways on the Roof of the World Author:Wang Quanquan Paperback,155 pages Published by Foreign Languages Press The jade-green Fuxing(rejuvenation)bullet train,snow white hada(prayer scarves),and beaming faces keep flashing into the photographer’s lens.
基金the Office of Research&Economic Development and Department of Civil,Coastal and Environmental Engineering at University of South Alabama for the support.
文摘The utilization of reclaimed asphalt pavement(RAP)in asphalt mixtures has gained momentum in recent years,yet concerns persist regarding the long-term performance and binder properties of high RAP content mixtures.To overcome these challenges,rejuvenators have emerged as a promising solution to enhance the properties of aged asphalt binders and improve the overall performance of asphalt mixtures.This paper provides a comprehensive state-of-the-art review of rejuvenator technology and its potential to enhance the performance and sustainability of asphalt pavements.Rejuvenators are additives used to restore the properties of aged asphalt binders,particularly when incorporating high percentages of RAP.The performance of these additives varies based on their origin,and different methods can be used to analyze the rejuvenation process.Since proper specifications for rejuvenators are not available,blending charts are used to determine the optimum dosage of rejuvenators.However,proper blending must be achieved to maximize results and reduce the effect of black rock.Laboratory tests and some field performance studies on rejuvenated aged asphalt binders and RAP mixtures have shown improved or similar performance compared to virgin materials.Additionally,the use of rejuvenators has been observed to reduce construction costs,suggesting that this is a cost-effective technology for asphalt pavements.While rejuvenators show promise in improving the performance of pavements with recycled materials,challenges remain regarding optimization,long-term durability,and environmental effects.This review paper also identifies key areas for future research,including life-cycle cost analyses,comprehensive environmental impact assessments,and long-term field performance monitoring.
基金support from the National Natural Science Foundation of China(No.52231006)Junqiang Wang acknowledges financial support from the National Key R&D Program of China(No.2018YFA0703600)the National Natural Science Foundation of China(Nos.92163108 and 52222105).
文摘Annealing has been a popular method to improve the soft magnetism of metallic glasses (MGs), which however usually makes MGs brittle and difficult to process. Here, it is demonstrated that the embrittled Fe-based MG can be reductilized and the coercivity can be further lowered through the rejuvenation of memory effect. The synchronous improvement in the plasticity and soft magnetic properties is attributed to the combination effects of releasing much residual stress, decreasing the magnetic anisotropy, and homogenizing the glasses during the rejuvenation process. The current work opens a new perspective to improve the properties of MGs by utilizing the memory effect and holds promising commercial application potential.
基金supported by the National Natural Science Foundation of China(No.52175286)the Tribology Science Fund of State Key Laboratory of Tribology in Advanced Equipment,Tsinghua University,China(No.SKLTKF20B16).
文摘The effects of rejuvenation heat treatment(RHT)on the serrated flow behavior and fracture mode of nickel-based superalloys(R26)were investigated by tensile tests and microstructural characterization.The serrated flow activation energies were determined to be 41−72 and 64−81 kJ/mol before and after RHT,respectively.Dynamic strain aging in the alloy is caused by the diffusion of carbon atoms into dislocation channels in the nickel matrix.Before RHT,carbides are concentrated at the grain boundaries.Cracks initiate from these carbides and propagate along the grain boundaries.RHT dissolves carbides at grain boundaries,transferring crack initiation to the precipitated phase group in the grains.RHT increases carbon atom concentration in the nickel matrix,enhancing dynamic strain aging and serrated flow behavior.
文摘“Transformation is not simply about shutting down;it is more about eliminating outdated production capacity while nurturing new driving forces,”according to Wan Qian,a member of the Standing Committee of the Xiangxiang Municipal Party Committee,referring to an eco-friendly chemical industrial park in Xiangxiang City,central China’s Hunan Province.
基金supported by Liaoning Joint Fund of NSFC(No.U1908219)。
文摘The effects of deep cryogenic-cycling treatment(DCT)on the mechanical properties,soft magnetic properties,and atomic scale structure of the Fe_(73.5)Si_(13.5)B_(9)Nb_(3)Cu_(1)amorphous nanocrystalline alloy were investigated.The DCT samples were obtained by subjecting the as-annealed samples to a thermal cycling process between the temperature of the supercooled liquid zone and the temperature of liquid nitrogen.Through flat plate bending testing,hardness measurements,and nanoindentation experiment,it is found that the bending toughness of the DCT samples is improved and the soft magnetic properties are also slightly enhanced.These are attributed to the rejuvenation behavior of the DCT samples,which demonstrate a higher enthalpy of relaxation.Therefore,DCT is an effective method to enhance the bending toughness of Fe-based amorphous nanocrystalline alloys without degrading the soft magnetic properties.
文摘With socialism with Chinese characteristics entering into a new era,the great rejuvenation of the Chinese nation is now on an irreversible course.China has come ever closer to the center stage of the world.Grasping the international landscape,the pulse of the times,the trends of the world,and with the progress of human development in mind,General Secretary Xi Jinping has put forward a series of original diplomatic concepts and major initiatives,creating the Xi Jinping Thought on Diplomacy.
基金supported by the Research Project titled“The Role of the Global Development Initiative in Promoting Balanced,Coordinated and Inclusive Global Development”(ID:3162022ZYE03)funded by the Basic Research Funds for Centrally Administered Institutions of Tertiary Education.
文摘The history and practice of the great rejuvenation of the Chinese nation show that the founding of the Communist Party of China(CPC)has opened up a new era in the Chinese history and the CPC constitutes the fundamental leadership and organizational guarantee for the realization of the great rejuvenation of the Chinese nation.The CPC has united and led the Chinese people in having founded the People’s Republic of China(PRC),in having established the basic socialist system,in having eliminated all exploitation systems,and in having laid the fundamental political premise and institutional foundation for the great rejuvenation of the Chinese nation.The CPC has also led the Chinese people in having carried out Reform and Opening-up,in having launched the road of socialism with Chinese characteristics,and in having realized the great leap of the Chinese nation from standing up to becoming rich.Since its 18th National Congress,standing at the historical starting point of the new era,the CPC has led the people in unremitting struggle,has opened up a new realm of socialism with Chinese characteristics in the new era,and has achieved a historical breakthrough for the Chinese nation from becoming rich to becoming strong.The course of the CPC leading the Chinese people to realize the great rejuvenation of the Chinese nation reflects the systematic thinking of economic development and the integrated utilization of Marxist theory of economic development and traditional theories of economic development.The history of the CPC uniting and leading the people to strive for the great rejuvenation of the Chinese nation enlightens us that the CPC,as the“visible hand”of the cause of socialism with Chinese characteristics,is the fundamental guarantee for the great rejuvenation of the Chinese nation,and China must adhere to the CPC’s leadership.
