The advancement of electron microscopy technology has driven the development of electron microscopes that can apply mechanical loading while observing samples,providing a valuable tool for In-Situ mechanical character...The advancement of electron microscopy technology has driven the development of electron microscopes that can apply mechanical loading while observing samples,providing a valuable tool for In-Situ mechanical characterization of materials.In response to the need to characterize the evolution of the mechanical behavior of structural materials,such as aerospace materials,in real cryogenic service environments,and to provide an experimental basis for improving their macroscopic cryogenic mechanical properties,the advancement of In-Situ characterization techniques capable of offering both cryogenic environments and mechanical loading has become imperative.There have been scholars using this technique to carry out cryogenic mechanical In-Situ studies of related materials,with experimental studies dominating in general,and a few reviews of mechanical characterization techniques mentioning cryogenic temperatures.In order to make it easier to conduct research using such characterization techniques and to further promote the development of related characterization techniques,this review compiles the previous work and summarizes the electron microscope-based In-Situ characterization techniques for cryogenic micro-and nanomechanics.These techniques primarily include transmission electron microscopy-based cryogenic tensile and indentation methods,as well as scanning electron microscopy-based cryogenic tensile,indentation,compression,and bending methods.Furthermore,the review outlines the prospective future development of In-Situ characterization techniques for cryogenic micro-and nanomechanics.展开更多
With the rapid development of portable electronics,new energy vehicles,and smart grids,ion batteries are becoming one of the most widely used energy storage devices,while the safety concern of ion batteries has always...With the rapid development of portable electronics,new energy vehicles,and smart grids,ion batteries are becoming one of the most widely used energy storage devices,while the safety concern of ion batteries has always been an urgent problem to be solved.To develop a safety-guaranteed battery,the characterization of the internal structure is indispensable,where electron microscopy plays a crucial role.Based on this,this paper summarizes the application of transmission electron microscopy(TEM)in battery safety,further concludes and analyzes the aspects of dendrite growth and solid electrolyte interface(SEI)formation that affect the safety of ion batteries,and emphasizes the importance of electron microscopy in battery safety research and the potential of these techniques to promote the future development of this field.These advanced electron microscopy techniques and their prospects are also discussed.展开更多
High-lead solder joints are still playing an indispensable role in military and space applications.Nevertheless,in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain une...High-lead solder joints are still playing an indispensable role in military and space applications.Nevertheless,in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored.This research first performed aging tests on Sn10Pb90 solder joints,the shear strength at room and elevated temperatures gradually reduced,and the resistance increased.Here,a two-layered Ni-Sn intermetallic compound(IMC)structure was identified using transmission electron microscopy(TEM),which could be attributed to the change of Sn content in the solder.Moreover,the internal annealing twin of a Sn particle was discovered,which could be attributed to creeping induced by thermal expansion coefficient(CTE)difference between Sn and Pb.Detailed analysis of partial and whole annealing twins was conducted through high-resolution TEM(HRTEM).Finally,four degradation mechanisms were proposed.Thickening of the IMC layer would result in increased brittleness and resistivity.For particle coarsening,apart from diminishing the ductility and toughness of the solder joint,it would also accelerate the creeping rate by weakening the phase boundary strength.Regarding voids and cracks induced by phase boundary sliding,wedgeshaped cracking and pore-shaped cracking were discovered and their formation was analyzed.Most importantly,the consumption of Sn resulted in a depletion of wettable layer,leading to the formation of Pb streams and isolated IMC islands,also known as the spalling and delamination of IMCs.Pb diffusion followed a spiral path,which was mutually influenced by orientation misfit and concentration gradient.A technique to prevent cracking was proposed.This research is expected to provide significant technical references for high-lead solder joints.展开更多
The corrosion behavior of 304LN austenitic stainless steel in supercritical CO_(2) at 650℃ was investigated.The results show that 304LN follows Wagner’s law kinetics,forming a protective oxide flm consisting of SiO_...The corrosion behavior of 304LN austenitic stainless steel in supercritical CO_(2) at 650℃ was investigated.The results show that 304LN follows Wagner’s law kinetics,forming a protective oxide flm consisting of SiO_(2),(Cr,Mn)3O_(4),and Cr2O_(3) from the inner to outer layers.A shallow carburization depth of approximately 130 nm indicates excellent resistance to carburization.The roles of key elements in 18/8 austenitic stainless steel represented by 304LN,such as Cr,Ni,and Si,were analyzed,highlighting their contributions to anti-carburization performance and corrosion resistance under harsh conditions.展开更多
The physical metallurgy underlying the development of cast microstructures in abrasion resistant high chromium cast irons, and their structural modification by thermal treatments is relatively complex. Structural char...The physical metallurgy underlying the development of cast microstructures in abrasion resistant high chromium cast irons, and their structural modification by thermal treatments is relatively complex. Structural characterisation via electron microscopy therefore has a key role to play in furthering our understanding of the phase transformations that control the microstructures and hence the service performances of these irons as wear parts. This paper shows how both scanning and especially transmission electron microscopy can provide valuable information on the nature of eutectic and secondary carbides and on the matrix structures in these irons. Particular attention is given to current characterisation research on conventionally cast 30%Cr irons that are used for applications involving corrosive wear e.g. slurry pumps and on a semi-solid cast 27%Cr iron that has a potential for applications in industry.展开更多
In recent decades,materials science has experienced rapid development and posed increasingly high requirements for the characterizations of structures,properties,and performances.Herein,we report on our recent establi...In recent decades,materials science has experienced rapid development and posed increasingly high requirements for the characterizations of structures,properties,and performances.Herein,we report on our recent establishment of a multi-domain(energy,space,time)highresolution platform for integrated spectroscopy and microscopy characterizations,offering an unprecedented way to analyze materials in terms of spectral(energy)and spatial mapping as well as temporal evolution.We present several proof-of-principle results collected on this platform,including in-situ Raman imaging(high-resolution Raman,polarization Raman,low-wavenumber Raman),time-resolved photoluminescence imaging,and photoelectrical performance imaging.It can be envisioned that our newly established platform would be very powerful and effective in the multi-domain high-resolution characterizations of various materials of photoelectrochemical importance in the near future.展开更多
The microstructure of nickel-base alloy C-276 irradiated at 500 ℃ with 300 keY self-ions （Ni^＋） to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Bot...The microstructure of nickel-base alloy C-276 irradiated at 500 ℃ with 300 keY self-ions （Ni^＋） to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Both black spots and dislocation loops were observed. The black spots were identified as small dislocation loops, with a density of （8.2±0.2）x10^15 cm^-3 and the average loop size of about 15 nm. An increase of dislocation loop density would lead to the increase of the hardness in C-276 alloy, and the increment in yield strength was estimated by the dispersed barrier-hardening model. In [110] orientation, Burgers vectors of the dislocation loops were determined, and it was found that they were predominantly （a/2）〈110〉. In contrast to other nickel-base alloys, no voids were observed in C-276 alloy after being irradiated at elevated temperatures.展开更多
Structural and functional explorations on bio-soft matter such as micelles,vesicles,nanoparticles,aggregates or polymers derived from traditional Chinese medicine(TCM)has emerged as a new topic in the field of TCM.The...Structural and functional explorations on bio-soft matter such as micelles,vesicles,nanoparticles,aggregates or polymers derived from traditional Chinese medicine(TCM)has emerged as a new topic in the field of TCM.The discovery of such cross-scaled bio-soft matter may provide a unique perspective for unraveling the new effective material basis of TCM as well as developing innovative medicine and biomaterials.Despite the rapid rise of TCM-derived bio-soft matter,their hierarchical structure and assembly mechanism must be unambiguously probed for a further in-depth understanding of their pharmacological activity.In this review,the current emerged TCM-derived bio-soft matter assembled from either small molecules or macromolecules is introduced,and particularly the unambiguous elucidation of their hierarchical structure and assembly mechanism with combined electron microscopic and spectroscopic techniques is depicted.The pros and cons of each technique are also discussed.The future challenges and perspective of TCM-derived bio-soft matter are outlined,particularly the requirement for their precise in situ structural determination is highlighted.展开更多
A new method to visualize the large-scale crystal grain morphology of organic polycrystalline films is proposed. First,optical anisotropic transmittance images of polycrystalline zinc phthalocyanine（Zn Pc） films vac...A new method to visualize the large-scale crystal grain morphology of organic polycrystalline films is proposed. First,optical anisotropic transmittance images of polycrystalline zinc phthalocyanine（Zn Pc） films vacuum deposited by weak epitaxial growth（WEG） method were acquired with polarized optical microscopy（POM）. Then morphology properties including crystal grain size, distribution, relative orientation, and crystallinity were derived from these images by fitting with a transition dipole model. At last, atomic force microscopy（AFM） imaging was carried out to confirm the fitting and serve as absolute references. This method can be readily generalized to other organic polycrystalline films, thus providing an efficient way to access the large-scale morphologic properties of organic polycrystalline films, which may prove to be useful in industry as a film quality monitoring method.展开更多
Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionall...Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.展开更多
In this paper,two ways of micro structural characterization,optical microscopy(OM) and polarized light microscopy(PLM),were both employed to describe the micro structure of semisolid slurry prepared by swirling enthal...In this paper,two ways of micro structural characterization,optical microscopy(OM) and polarized light microscopy(PLM),were both employed to describe the micro structure of semisolid slurry prepared by swirling enthalpy equilibration device(SEED).The results show that PLM is more reliable and accurate than OM to describe the special morphology feature of semisolid slurry made by SEED process.Meanwhile,the effects of pouring temperature and mass of molten liquid on the primary α-Al particle size and morphology were also investigated using PLM.The quantitative metallographic results measured from PLM demonstrate that the grain size and morphology and their distribution are significantly affected by both pouring temperature and the mass of molten liquid.The grain size poured with 2.7 kg liquid decreases from 659 to186 μm,and grain morphology transforms from dendrite to globular structure with pouring temperature reducing from690 to 630℃.The decreasing pouring temperature also promotes the distribution of spherical structure on the cross section.Meanwhile,the mass of molten liquid decreasing from 2.7 to 2.3 kg can decrease the grain size by maximum of 44% at high pouring temperature.展开更多
The various morphologies of tracks in MoS2 irradiated by swift heavy ions at normal and 30° incidence with 9.5–25.0 MeV/u 86Kr, 129Xe, 181Ta, and 209Bi ions were investigated by transmission electron microscopy....The various morphologies of tracks in MoS2 irradiated by swift heavy ions at normal and 30° incidence with 9.5–25.0 MeV/u 86Kr, 129Xe, 181Ta, and 209Bi ions were investigated by transmission electron microscopy. The diameter of ion tracks increases from 1.9 nm to 4.5 nm with increasing electronic energy loss. The energy loss threshold of the track formation in MoS2 is predicted as about 9.7 keV/nm based on the thermal spike model and it seems consistent with the experimental results. It is shown that the morphology of ion tracks is related to the penetration length of ions in MoS2. The formation process of ion tracks is discussed based on the cooperative process of outflow and recrystallization of the molten phase during rapid quenching.展开更多
Bacteriophages or more commonly ＂phages＂ are bacterial viruses. They are ubiquitous and good indicators of bacterial contaminations since their prevalence is high in those environments where their hosts are abundant...Bacteriophages or more commonly ＂phages＂ are bacterial viruses. They are ubiquitous and good indicators of bacterial contaminations since their prevalence is high in those environments where their hosts are abundant. Phage classification is based on morphology and for this reason, even though it is considered an old technique, TEM （Transmission Electron Microscopy） still plays a key role in their characterization. In the present work, the authors focused on TEM analysis of phage ФApr-1 isolated against Lactococcuslactis （L. lactis）, implicated in industrial fermentations and of phage ФIZSAM-1, active against Listeria monocytogenes （L. monocytogenes）, isolated from the environment. For observation with TEM （EM 900T-Zeiss）, phages were harvested in liquid media and were negative stained with fosfotungstic acid 2‰. An accurate viral ultrastructure analysis by using TEM is fundamental not only in the first approach of characterization of newly isolated phages but also for providing useful information to go further to the selection process as potential bio-decontaminants.展开更多
One of the most intriguing methods of mitigating the hydrogen embrittlement of steels entails nano-precipitates that can trap H from enriching at vulnerable locations.However,controversial findings have been reported ...One of the most intriguing methods of mitigating the hydrogen embrittlement of steels entails nano-precipitates that can trap H from enriching at vulnerable locations.However,controversial findings have been reported on whether the incoherent NbC precipitates trap hydrogen.Here,by using in-situ scan-ning Kelvin probe force microscopy(SKPFM),we reveal the dynamic interaction of H with the border area of incoherent NbC nanoprecipitates in steel.Results indicate that the interaction between H flux and the interfaces varies amongst different precipitates,implying that H-trapping behaviours of incoherent NbC precipitates could be intrinsically diverse.Potential origins underlying the distinct behaviours are analyzed.展开更多
Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~...Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~C. Transmission electron microscopy （TEM） is used to characterize the size and morphology of He bubbles. With the increase of the implantation temperature, TEM observations indicate that bubbles increase in size and the proportion of ＇brick shaped＇ cuboid bubbles increases while the proportion of polyhedral bubbles decreases in both the steel samples. For the samples implanted at the same temperature, the average size of He bubbles in MNHS is smaller than that in T91. This might be due to the abundance of boundaries and precipitates in MNHS, which provide additional sites for the trapping of He atoms, thus reduce the susceptibility of MNHS to He embrittlement.展开更多
基金supported by the National Natural Science Foundation of China(52301177)。
文摘The advancement of electron microscopy technology has driven the development of electron microscopes that can apply mechanical loading while observing samples,providing a valuable tool for In-Situ mechanical characterization of materials.In response to the need to characterize the evolution of the mechanical behavior of structural materials,such as aerospace materials,in real cryogenic service environments,and to provide an experimental basis for improving their macroscopic cryogenic mechanical properties,the advancement of In-Situ characterization techniques capable of offering both cryogenic environments and mechanical loading has become imperative.There have been scholars using this technique to carry out cryogenic mechanical In-Situ studies of related materials,with experimental studies dominating in general,and a few reviews of mechanical characterization techniques mentioning cryogenic temperatures.In order to make it easier to conduct research using such characterization techniques and to further promote the development of related characterization techniques,this review compiles the previous work and summarizes the electron microscope-based In-Situ characterization techniques for cryogenic micro-and nanomechanics.These techniques primarily include transmission electron microscopy-based cryogenic tensile and indentation methods,as well as scanning electron microscopy-based cryogenic tensile,indentation,compression,and bending methods.Furthermore,the review outlines the prospective future development of In-Situ characterization techniques for cryogenic micro-and nanomechanics.
基金supported by the National Natural Science Foundation of China(No.22209027)the Shenzhen Science and Technology Program(No.JCYJ20220530142806015 and No.JCYJ20220818101008018)+1 种基金the Shenzhen“Pengcheng Peacock Program’the Tsinghua SIGS Cross-disciplinary Research and Innovation Fund(No.JC2022002)。
文摘With the rapid development of portable electronics,new energy vehicles,and smart grids,ion batteries are becoming one of the most widely used energy storage devices,while the safety concern of ion batteries has always been an urgent problem to be solved.To develop a safety-guaranteed battery,the characterization of the internal structure is indispensable,where electron microscopy plays a crucial role.Based on this,this paper summarizes the application of transmission electron microscopy(TEM)in battery safety,further concludes and analyzes the aspects of dendrite growth and solid electrolyte interface(SEI)formation that affect the safety of ion batteries,and emphasizes the importance of electron microscopy in battery safety research and the potential of these techniques to promote the future development of this field.These advanced electron microscopy techniques and their prospects are also discussed.
基金financially supported by Chongqing Natural Science Foundation of China(No.cstc2021jcyjmsxmX1002)the Ministry of Industry and Information Technology of the People’s Republic of China(Nos.1GWZ2326032 and 302JC22123006)。
文摘High-lead solder joints are still playing an indispensable role in military and space applications.Nevertheless,in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored.This research first performed aging tests on Sn10Pb90 solder joints,the shear strength at room and elevated temperatures gradually reduced,and the resistance increased.Here,a two-layered Ni-Sn intermetallic compound(IMC)structure was identified using transmission electron microscopy(TEM),which could be attributed to the change of Sn content in the solder.Moreover,the internal annealing twin of a Sn particle was discovered,which could be attributed to creeping induced by thermal expansion coefficient(CTE)difference between Sn and Pb.Detailed analysis of partial and whole annealing twins was conducted through high-resolution TEM(HRTEM).Finally,four degradation mechanisms were proposed.Thickening of the IMC layer would result in increased brittleness and resistivity.For particle coarsening,apart from diminishing the ductility and toughness of the solder joint,it would also accelerate the creeping rate by weakening the phase boundary strength.Regarding voids and cracks induced by phase boundary sliding,wedgeshaped cracking and pore-shaped cracking were discovered and their formation was analyzed.Most importantly,the consumption of Sn resulted in a depletion of wettable layer,leading to the formation of Pb streams and isolated IMC islands,also known as the spalling and delamination of IMCs.Pb diffusion followed a spiral path,which was mutually influenced by orientation misfit and concentration gradient.A technique to prevent cracking was proposed.This research is expected to provide significant technical references for high-lead solder joints.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA0410000)the CAS Project for Young Scientists in Basic Research(No.YSBR-043)+1 种基金the CNNC Science Fund for Talented Young Scholars,the National Funding Program for Postdoctoral Researchers(GZC20232747)the Youth Innovation Promotion Association CAS(2022187).
文摘The corrosion behavior of 304LN austenitic stainless steel in supercritical CO_(2) at 650℃ was investigated.The results show that 304LN follows Wagner’s law kinetics,forming a protective oxide flm consisting of SiO_(2),(Cr,Mn)3O_(4),and Cr2O_(3) from the inner to outer layers.A shallow carburization depth of approximately 130 nm indicates excellent resistance to carburization.The roles of key elements in 18/8 austenitic stainless steel represented by 304LN,such as Cr,Ni,and Si,were analyzed,highlighting their contributions to anti-carburization performance and corrosion resistance under harsh conditions.
文摘The physical metallurgy underlying the development of cast microstructures in abrasion resistant high chromium cast irons, and their structural modification by thermal treatments is relatively complex. Structural characterisation via electron microscopy therefore has a key role to play in furthering our understanding of the phase transformations that control the microstructures and hence the service performances of these irons as wear parts. This paper shows how both scanning and especially transmission electron microscopy can provide valuable information on the nature of eutectic and secondary carbides and on the matrix structures in these irons. Particular attention is given to current characterisation research on conventionally cast 30%Cr irons that are used for applications involving corrosive wear e.g. slurry pumps and on a semi-solid cast 27%Cr iron that has a potential for applications in industry.
基金supported by the National Key Research and Development Program of China(No.2016YFA0200602,No.2017YFA0303500,and No.2018YFA0208702)the National Natural Science Foundation of China(No.21573211,No.21633007,No.21803067,and No.91950207)+1 种基金the Anhui Initiative in Quantum Information Technologies(AHY090200)the USTC-NSRL Joint Funds(UN2018LHJJ).
文摘In recent decades,materials science has experienced rapid development and posed increasingly high requirements for the characterizations of structures,properties,and performances.Herein,we report on our recent establishment of a multi-domain(energy,space,time)highresolution platform for integrated spectroscopy and microscopy characterizations,offering an unprecedented way to analyze materials in terms of spectral(energy)and spatial mapping as well as temporal evolution.We present several proof-of-principle results collected on this platform,including in-situ Raman imaging(high-resolution Raman,polarization Raman,low-wavenumber Raman),time-resolved photoluminescence imaging,and photoelectrical performance imaging.It can be envisioned that our newly established platform would be very powerful and effective in the multi-domain high-resolution characterizations of various materials of photoelectrochemical importance in the near future.
基金supported by the National Basic Research Program of China(No.2007CB2009800)the National Natural Science Foundation of China(Nos.11075119and11275140)+1 种基金the Fundamental Research Funds for the Central Universities(No.20102020201000013)the National Magnetic Confinement Fusion Program(No.2011GB108009)
文摘The microstructure of nickel-base alloy C-276 irradiated at 500 ℃ with 300 keY self-ions （Ni^＋） to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Both black spots and dislocation loops were observed. The black spots were identified as small dislocation loops, with a density of （8.2±0.2）x10^15 cm^-3 and the average loop size of about 15 nm. An increase of dislocation loop density would lead to the increase of the hardness in C-276 alloy, and the increment in yield strength was estimated by the dispersed barrier-hardening model. In [110] orientation, Burgers vectors of the dislocation loops were determined, and it was found that they were predominantly （a/2）〈110〉. In contrast to other nickel-base alloys, no voids were observed in C-276 alloy after being irradiated at elevated temperatures.
基金supported by the National Natural Science Foundation of China(Grant No.:82374033,21901067)Ministry of Science and Technology of China(Grant No.:2023YFC3504100)Starting Grant from the Ministry of Human Resource and Social Security of China(Quan Li).
文摘Structural and functional explorations on bio-soft matter such as micelles,vesicles,nanoparticles,aggregates or polymers derived from traditional Chinese medicine(TCM)has emerged as a new topic in the field of TCM.The discovery of such cross-scaled bio-soft matter may provide a unique perspective for unraveling the new effective material basis of TCM as well as developing innovative medicine and biomaterials.Despite the rapid rise of TCM-derived bio-soft matter,their hierarchical structure and assembly mechanism must be unambiguously probed for a further in-depth understanding of their pharmacological activity.In this review,the current emerged TCM-derived bio-soft matter assembled from either small molecules or macromolecules is introduced,and particularly the unambiguous elucidation of their hierarchical structure and assembly mechanism with combined electron microscopic and spectroscopic techniques is depicted.The pros and cons of each technique are also discussed.The future challenges and perspective of TCM-derived bio-soft matter are outlined,particularly the requirement for their precise in situ structural determination is highlighted.
基金Project supported by the National Natural Science Foundation of China(Grant No.20933010)the National Basic Research Program of China(Grant No.2013CB834800)
文摘A new method to visualize the large-scale crystal grain morphology of organic polycrystalline films is proposed. First,optical anisotropic transmittance images of polycrystalline zinc phthalocyanine（Zn Pc） films vacuum deposited by weak epitaxial growth（WEG） method were acquired with polarized optical microscopy（POM）. Then morphology properties including crystal grain size, distribution, relative orientation, and crystallinity were derived from these images by fitting with a transition dipole model. At last, atomic force microscopy（AFM） imaging was carried out to confirm the fitting and serve as absolute references. This method can be readily generalized to other organic polycrystalline films, thus providing an efficient way to access the large-scale morphologic properties of organic polycrystalline films, which may prove to be useful in industry as a film quality monitoring method.
文摘Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.
基金financially supported by the National Key Research and Development Program of China (No. 2016YFB0301003)the Shenzhen Free Exploring Basic Research Project (No. JCYJ20170307110223452)。
文摘In this paper,two ways of micro structural characterization,optical microscopy(OM) and polarized light microscopy(PLM),were both employed to describe the micro structure of semisolid slurry prepared by swirling enthalpy equilibration device(SEED).The results show that PLM is more reliable and accurate than OM to describe the special morphology feature of semisolid slurry made by SEED process.Meanwhile,the effects of pouring temperature and mass of molten liquid on the primary α-Al particle size and morphology were also investigated using PLM.The quantitative metallographic results measured from PLM demonstrate that the grain size and morphology and their distribution are significantly affected by both pouring temperature and the mass of molten liquid.The grain size poured with 2.7 kg liquid decreases from 659 to186 μm,and grain morphology transforms from dendrite to globular structure with pouring temperature reducing from690 to 630℃.The decreasing pouring temperature also promotes the distribution of spherical structure on the cross section.Meanwhile,the mass of molten liquid decreasing from 2.7 to 2.3 kg can decrease the grain size by maximum of 44% at high pouring temperature.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11675233,11690041,11405229,11705246,and 11505243)Chinese Academy of Sciences “Light of West China” Programthe Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant No. 2020412)。
文摘The various morphologies of tracks in MoS2 irradiated by swift heavy ions at normal and 30° incidence with 9.5–25.0 MeV/u 86Kr, 129Xe, 181Ta, and 209Bi ions were investigated by transmission electron microscopy. The diameter of ion tracks increases from 1.9 nm to 4.5 nm with increasing electronic energy loss. The energy loss threshold of the track formation in MoS2 is predicted as about 9.7 keV/nm based on the thermal spike model and it seems consistent with the experimental results. It is shown that the morphology of ion tracks is related to the penetration length of ions in MoS2. The formation process of ion tracks is discussed based on the cooperative process of outflow and recrystallization of the molten phase during rapid quenching.
文摘Bacteriophages or more commonly ＂phages＂ are bacterial viruses. They are ubiquitous and good indicators of bacterial contaminations since their prevalence is high in those environments where their hosts are abundant. Phage classification is based on morphology and for this reason, even though it is considered an old technique, TEM （Transmission Electron Microscopy） still plays a key role in their characterization. In the present work, the authors focused on TEM analysis of phage ФApr-1 isolated against Lactococcuslactis （L. lactis）, implicated in industrial fermentations and of phage ФIZSAM-1, active against Listeria monocytogenes （L. monocytogenes）, isolated from the environment. For observation with TEM （EM 900T-Zeiss）, phages were harvested in liquid media and were negative stained with fosfotungstic acid 2‰. An accurate viral ultrastructure analysis by using TEM is fundamental not only in the first approach of characterization of newly isolated phages but also for providing useful information to go further to the selection process as potential bio-decontaminants.
基金supported by the National Natural Science Foun-dation of China under grant Nos.52231003,52301073,52271049,and 52201063.
文摘One of the most intriguing methods of mitigating the hydrogen embrittlement of steels entails nano-precipitates that can trap H from enriching at vulnerable locations.However,controversial findings have been reported on whether the incoherent NbC precipitates trap hydrogen.Here,by using in-situ scan-ning Kelvin probe force microscopy(SKPFM),we reveal the dynamic interaction of H with the border area of incoherent NbC nanoprecipitates in steel.Results indicate that the interaction between H flux and the interfaces varies amongst different precipitates,implying that H-trapping behaviours of incoherent NbC precipitates could be intrinsically diverse.Potential origins underlying the distinct behaviours are analyzed.
基金Supported by the National Basic Research Program of China under Grant Nos 2010CB832902 and 91026002the National Natural Science Foundation of China under Grant No U1232121
文摘Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~C. Transmission electron microscopy （TEM） is used to characterize the size and morphology of He bubbles. With the increase of the implantation temperature, TEM observations indicate that bubbles increase in size and the proportion of ＇brick shaped＇ cuboid bubbles increases while the proportion of polyhedral bubbles decreases in both the steel samples. For the samples implanted at the same temperature, the average size of He bubbles in MNHS is smaller than that in T91. This might be due to the abundance of boundaries and precipitates in MNHS, which provide additional sites for the trapping of He atoms, thus reduce the susceptibility of MNHS to He embrittlement.
