Comprehending the pressure-/temperature-induced structural transition in glasses,as one of the most fascinating issues in material science,is far from being well understood.Here,we report novel polyamorphic transition...Comprehending the pressure-/temperature-induced structural transition in glasses,as one of the most fascinating issues in material science,is far from being well understood.Here,we report novel polyamorphic transitions in a Cu-based metallic glass(MG)with apparent nanoscale structural heterogeneity relating to proper Y addition.The low-density MG compresses continuously with increasing pressure,and then a compression plateau appears after∼8.1 GPa,evolving into an intermediate state with an ultrahigh bulk modulus of∼467 GPa.It then transforms to a high-density MG with significantly decreased structural heterogeneity above∼14.1 GPa.Three-dimensional atom probe tomography reveals concentration waves of Cu/Zr elements with an average wavelength of∼5-6 nm,which promote the formation of interconnected ringlike networks composed of Cu-rich and Zr-rich dual-glass domains at nanometer scale.Our experimental and simulation results indicate that steplike polyamorphism may stem from synergic effects of the abnormal compression of the Zr-Zr bond length at the atomic scale and the interplay between the applied pressure and incipient concentration waves(Cu and Zr)at several nanometer scales.The present work provides new insights into polyamorphism in glasses and contributes to the development of high-performance amorphous materials by high-pressure nanostructure engineering.展开更多
In this paper, based on complex variables and conformal mapping methods, using the refined dynamic equation of plates, elastic wave scattering and dynamic stress concentrations in plates with two cutouts were studied....In this paper, based on complex variables and conformal mapping methods, using the refined dynamic equation of plates, elastic wave scattering and dynamic stress concentrations in plates with two cutouts were studied. Applying the orthogonal function expansion method, the problem to be solved can be reduced into the solution of a set of infinite algebraic equations. According to free boundary conditions, numerical results of dynamic moment concentration factors in thick plates with two circular cutouts analyze that: there will be more complex interaction changes between two-cutout situation than single cutout situation. In the case of low frequency or high frequency and thin plate, the hole-spacing in the absence of coupling interactions was larger or smaller. The numerical results and method can be used to analyze the dynamics and strength of plate-like structures.展开更多
Concentric gravity waves(CGWs)in the middle and upper atmosphere show wave-coupling processes between the lower atmosphere and the middle and upper atmosphere.In this research,we analyzed a case of CGWs detected simul...Concentric gravity waves(CGWs)in the middle and upper atmosphere show wave-coupling processes between the lower atmosphere and the middle and upper atmosphere.In this research,we analyzed a case of CGWs detected simultaneously by the AIRS(Atmospheric Infrared Sounder)and the VIIRS/DNB(Day/Night Band of the Visible Infrared Imager Radiometer Suite)in the stratosphere and mesosphere.Results showed that gravity waves(GWs)were generated by the collocated Hurricane Bejisa on the island of Mauritius.The AIRS data showed arc-like phase fronts of GWs with horizontal wavelengths of 190 and 150 km at 21:08 coordinated universal time(UTC)on 1 January 2014 and at 10:00 UTC on 2 January 2014,whereas the DNB observed arced GWs with horizontal wavelengths of 60 and 150 km in the same geographic regions at 22:24 UTC.The characteristics of CGW parameters in the stratosphere(~40 km)and the mesosphere(~87 km),such as the vertical wavelength,intrinsic frequency,and intrinsic horizontal phase speed,were first derived together with the background winds from ERA5 reanalysis data and Horizontal Wind Model data through the dispersion relationship of GWs and the wind-filtering theory.展开更多
Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem ...Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem to be solved is changed to a set of infinite algebraic equations by an orthogonM function expansion method. As examples, under free boundary conditions, the numerical results of the dynamic moment concen- tration factors in the plates with two circular holes are computed. The results indicate that the parameters such as the incident wave number, the thickness of plates, and the spacing between holes have great effects on the dynamic stress distributions. The results are accurate because the refined equation is derived without any engineering hypothese.展开更多
A concentric gravity wave event was captured by a photographer in NagarzêCounty(90.28°N,28.33°E)between 02:00 and 04:00(local time)on May 11,2019.This concentric gravity wave event was also observed by ...A concentric gravity wave event was captured by a photographer in NagarzêCounty(90.28°N,28.33°E)between 02:00 and 04:00(local time)on May 11,2019.This concentric gravity wave event was also observed by the Suomi National Polar-orbiting Partnership satellite and the all-sky airglow imager at Yangbajing station(90.5°E,30.1°N).The temporal and spatial information on gravity waves from the photographs provided a rare opportunity to study the propagation of gravity waves over the Tibetan Plateau.According to wind and temperature data from the MERRA-2 reanalysis(Modern-Era Retrospective analysis for Research and Applications,Version 2)and empirical models(NRLMSISE-00[Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar Exosphere]and HWM[horizontal wind model]),we inversely derived the propagation trajectory from the observed wave pattern to the source region by using the ray-tracing method.The source of the concentric gravity wave was identified as deep convection in Bangladesh(90.6°E,25.0°N).The maximum background wind speed in the propagation direction(31.05 m/s)was less than the phase speed of 53 m/s,which is consistent with the wind-filtering theory.展开更多
On the basis of the Local Equilibrium Model (LEM), fine particles with large Richardson-Zaki exponent n show, under certain conditions during bed expansion and collapse, different dynamic behavior from particles wit...On the basis of the Local Equilibrium Model (LEM), fine particles with large Richardson-Zaki exponent n show, under certain conditions during bed expansion and collapse, different dynamic behavior from particles with small n. For an expansion process there may be a concentration discontinuity propagating upward from the distributor, and, on the contrary, for a collapse process there may be a progressively broadening and upward-propagating continuous transition zone instead of discontinuity. The predictions of the bed height variation and the discontinuity trace have been validated experimentally.展开更多
High entropy alloys exhibit excellent combination of mechanical properties because of the unique com-position fluctuations,termed as‘concentration wave’.The concentration wave was closely related to mul-tiple aspect...High entropy alloys exhibit excellent combination of mechanical properties because of the unique com-position fluctuations,termed as‘concentration wave’.The concentration wave was closely related to mul-tiple aspects,including the fluctuation of local strain energy,local atomic environment,electronegativity,etc.Here we report for the first time that the amplitude of the concentration wave can be mechani-cally tailored under cyclic deformation in a well-known Cantor alloy.Atomic-scale energy-dispersive X-ray spectroscopy(EDS)mapping reveals that cyclic deformation may dynamically induce the clustering of solute atoms with a size of 1-3 nm,thus resulting in a higher concentration wave amplitude.The con-centration wave promotes strong interactions between dislocations and local solute clusters.Aside from the typical Taylor strengthening contribution due to the presence of isolated dislocations,the strength enhancement from the mechanically induced composition fluctuations was quantified to be as high as∼70 MPa,about one-third of the yield strength of the alloy without pre-deformation.This opens up a novel strategy of designing high strength alloys by tailoring solute configurations.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51971061,52231005,and 52031016)the Fundamental Research Funds for the Central Universities(Grant No.2242020R10003).
文摘Comprehending the pressure-/temperature-induced structural transition in glasses,as one of the most fascinating issues in material science,is far from being well understood.Here,we report novel polyamorphic transitions in a Cu-based metallic glass(MG)with apparent nanoscale structural heterogeneity relating to proper Y addition.The low-density MG compresses continuously with increasing pressure,and then a compression plateau appears after∼8.1 GPa,evolving into an intermediate state with an ultrahigh bulk modulus of∼467 GPa.It then transforms to a high-density MG with significantly decreased structural heterogeneity above∼14.1 GPa.Three-dimensional atom probe tomography reveals concentration waves of Cu/Zr elements with an average wavelength of∼5-6 nm,which promote the formation of interconnected ringlike networks composed of Cu-rich and Zr-rich dual-glass domains at nanometer scale.Our experimental and simulation results indicate that steplike polyamorphism may stem from synergic effects of the abnormal compression of the Zr-Zr bond length at the atomic scale and the interplay between the applied pressure and incipient concentration waves(Cu and Zr)at several nanometer scales.The present work provides new insights into polyamorphism in glasses and contributes to the development of high-performance amorphous materials by high-pressure nanostructure engineering.
文摘In this paper, based on complex variables and conformal mapping methods, using the refined dynamic equation of plates, elastic wave scattering and dynamic stress concentrations in plates with two cutouts were studied. Applying the orthogonal function expansion method, the problem to be solved can be reduced into the solution of a set of infinite algebraic equations. According to free boundary conditions, numerical results of dynamic moment concentration factors in thick plates with two circular cutouts analyze that: there will be more complex interaction changes between two-cutout situation than single cutout situation. In the case of low frequency or high frequency and thin plate, the hole-spacing in the absence of coupling interactions was larger or smaller. The numerical results and method can be used to analyze the dynamics and strength of plate-like structures.
基金the Strategic Priority Research Program of Chinese Academy of Sciences(no.XDA17010301)the National Key Research and Development Program of China(no.2016YFB0501503)+1 种基金the National Natural Science Foundation of China(nos.4190503811872128,91952111,41575031)part of the China Postdoctoral Foundation Program(no.2015M580124)。
文摘Concentric gravity waves(CGWs)in the middle and upper atmosphere show wave-coupling processes between the lower atmosphere and the middle and upper atmosphere.In this research,we analyzed a case of CGWs detected simultaneously by the AIRS(Atmospheric Infrared Sounder)and the VIIRS/DNB(Day/Night Band of the Visible Infrared Imager Radiometer Suite)in the stratosphere and mesosphere.Results showed that gravity waves(GWs)were generated by the collocated Hurricane Bejisa on the island of Mauritius.The AIRS data showed arc-like phase fronts of GWs with horizontal wavelengths of 190 and 150 km at 21:08 coordinated universal time(UTC)on 1 January 2014 and at 10:00 UTC on 2 January 2014,whereas the DNB observed arced GWs with horizontal wavelengths of 60 and 150 km in the same geographic regions at 22:24 UTC.The characteristics of CGW parameters in the stratosphere(~40 km)and the mesosphere(~87 km),such as the vertical wavelength,intrinsic frequency,and intrinsic horizontal phase speed,were first derived together with the background winds from ERA5 reanalysis data and Horizontal Wind Model data through the dispersion relationship of GWs and the wind-filtering theory.
基金Project supported by the National Natural Science Foundation of China(Nos.51378451 and 51378245)
文摘Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem to be solved is changed to a set of infinite algebraic equations by an orthogonM function expansion method. As examples, under free boundary conditions, the numerical results of the dynamic moment concen- tration factors in the plates with two circular holes are computed. The results indicate that the parameters such as the incident wave number, the thickness of plates, and the spacing between holes have great effects on the dynamic stress distributions. The results are accurate because the refined equation is derived without any engineering hypothese.
基金funded by the Science Foundation of Chongqing(Grant No.cstc2020jcyj-msxmX0914)the Informatization Plan of the Chinese Academy of Sciences(Grant No.CAS-WX2021PY-0101)the Specialized Re-search Fund for State Key Laboratories.
文摘A concentric gravity wave event was captured by a photographer in NagarzêCounty(90.28°N,28.33°E)between 02:00 and 04:00(local time)on May 11,2019.This concentric gravity wave event was also observed by the Suomi National Polar-orbiting Partnership satellite and the all-sky airglow imager at Yangbajing station(90.5°E,30.1°N).The temporal and spatial information on gravity waves from the photographs provided a rare opportunity to study the propagation of gravity waves over the Tibetan Plateau.According to wind and temperature data from the MERRA-2 reanalysis(Modern-Era Retrospective analysis for Research and Applications,Version 2)and empirical models(NRLMSISE-00[Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar Exosphere]and HWM[horizontal wind model]),we inversely derived the propagation trajectory from the observed wave pattern to the source region by using the ray-tracing method.The source of the concentric gravity wave was identified as deep convection in Bangladesh(90.6°E,25.0°N).The maximum background wind speed in the propagation direction(31.05 m/s)was less than the phase speed of 53 m/s,which is consistent with the wind-filtering theory.
基金the National Natural Science Foundation of China (NSFC No. 20376083) Key Laboratory of Multiphase Reaction, Institute of Process Engineering, Chinese Academy of Sciences.
文摘On the basis of the Local Equilibrium Model (LEM), fine particles with large Richardson-Zaki exponent n show, under certain conditions during bed expansion and collapse, different dynamic behavior from particles with small n. For an expansion process there may be a concentration discontinuity propagating upward from the distributor, and, on the contrary, for a collapse process there may be a progressively broadening and upward-propagating continuous transition zone instead of discontinuity. The predictions of the bed height variation and the discontinuity trace have been validated experimentally.
基金supported by the Natural Science Foundation of China (NSFC)(No. 51922026)the Fundamental Research Funds for the Central Universities (Nos. N2102005 and N2002005)
文摘High entropy alloys exhibit excellent combination of mechanical properties because of the unique com-position fluctuations,termed as‘concentration wave’.The concentration wave was closely related to mul-tiple aspects,including the fluctuation of local strain energy,local atomic environment,electronegativity,etc.Here we report for the first time that the amplitude of the concentration wave can be mechani-cally tailored under cyclic deformation in a well-known Cantor alloy.Atomic-scale energy-dispersive X-ray spectroscopy(EDS)mapping reveals that cyclic deformation may dynamically induce the clustering of solute atoms with a size of 1-3 nm,thus resulting in a higher concentration wave amplitude.The con-centration wave promotes strong interactions between dislocations and local solute clusters.Aside from the typical Taylor strengthening contribution due to the presence of isolated dislocations,the strength enhancement from the mechanically induced composition fluctuations was quantified to be as high as∼70 MPa,about one-third of the yield strength of the alloy without pre-deformation.This opens up a novel strategy of designing high strength alloys by tailoring solute configurations.