Intermetallic formation in sludge during magnesium(Mg)melting,holding and high pressure die casting practices is a very important issue.But,very often it is overlooked by academia,original equipment manufacturers(OEM)...Intermetallic formation in sludge during magnesium(Mg)melting,holding and high pressure die casting practices is a very important issue.But,very often it is overlooked by academia,original equipment manufacturers(OEM),metal ingot producers and even die casters.The aim of this study was to minimize the intermetallic formation in Mg sludge via the optimization of the chemistry and process parameters.The Al8Mn5 intermetallic particles were identified by the microstructure analysis based on the Al and Mn ratio.The design of experiment(DOE)technique,Taguchi method,was employed to minimize the intermetallic formation in the sludge of Mg alloys with various chemical compositions of Al,Mn,Fe,and different process parameters,holding temperature and holding time.The sludge yield(SY)and intermetallic size(IS)was selected as two responses.The optimum combination of the levels in terms of minimizing the intermetallic formation were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,690℃ for the holding temperature and holding at 30 mins for the holding time,respectively.The best combination for smallest intermetallic size were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,630℃ for the holding temperature and holding at 60 mins for the holding time,respectively.Three groups of sludge factors,Chemical Sludge(CSF),Physical Sludge(PSF)and Comprehensive Sludge Factors(and CPSF)were established for prediction of sludge yields and intermetallic sizes in Al-containing Mg alloys.The CPSF with five independent variables including both chemical elements and process parameters gave high accuracy in prediction,as the prediction of the PSF with only the two processing parameters of the melt holding temperature and time showed a relatively large deviation from the experimental data.The Chemical Sludge Factor was primarily designed for small ingot producers and die casters with a limited melting and holding capacity,of which process parameters could be fixed easily.The Physical Sludge Factor could be used for mass production with a single type of Mg alloy,in which the chemistry fluctuation might be negligible.In large Mg casting suppliers with multiple melting and holding furnaces and a number of Mg alloys in production,the Comprehensive Sludge Factor should be implemented to diminish the sludge formation.展开更多
Inferior absolute strength and dissolution properties are the main bottlenecks for the widespread application of dissolvable magnesium alloys in complex working environments for unconventional oil and gas resources.He...Inferior absolute strength and dissolution properties are the main bottlenecks for the widespread application of dissolvable magnesium alloys in complex working environments for unconventional oil and gas resources.Here,a novel functional peak-aged Mg-9.5Gd-2.7Y-0.9Zn-0.8Cu-0.4Ni(wt.%) alloy for fracturing tools is reported,and it possesses an ultimate tensile strength of 457.6 MPa,ultimate compressive strength of 620.7 MPa and dissolution rate of ~43.7 mg·cm^(-2)·h^(-1) in 3 wt.% KCl solutions at 93℃.The excellent strength of the agedalloy is primarily attributed to the combination of grain refinement,long-period stacking ordered(LPSO) strengthening,and precipitation strengthening induced by stacking fault and β’ phase,among which the precipitation strengthening is dominant.Further investigations confirm that the corrosion is triggered from the micro-galvanic coupling between the Mg matrix and the cathodic lamellar and block LPSO phases.Strip-shaped corrosion pits along with LPSO phases are subsequently formed,significantly accelerating corrosion.The β’ precipitates can effectively improve the strength without compromising the dissolution rate because of their nanoscale size.This study provides an excellent material selection for dissolvable fracturing tools and presents a strategy by which a synergistic combination of strength and dissolution rate is achieved via peak-aging treatment.展开更多
The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on20...The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.展开更多
Sludge consisting of heavy element phases and oxides is often generated during the casting operation of aluminum(Al)and magnesium(Mg)alloys.With the help of the well-established Sludge Factor(SF)formula,it is relative...Sludge consisting of heavy element phases and oxides is often generated during the casting operation of aluminum(Al)and magnesium(Mg)alloys.With the help of the well-established Sludge Factor(SF)formula,it is relatively easy to control the sludge generation in aluminum alloys.But formation mechanisms and characteristics of sludge in die casting magnesium alloys are still unclear.To ensure the production of high quality die cast components at a low cost,a full understanding of sludge in die casting Mg alloys and its proper control measures need to be developed,since excessive sludge formation affects deleteriously material and operation cost,and casting performance.In the present report,the formation,characteristics and control of Mg die-casting sludge,based on the established knowledge of sludge formation and sludge factor in Al die casting alloys,are reviewed.Previous work on characterization and assessment of sludge in die cast Mg alloys are reviewed.Metallurgical principles for control of sludge in ingot production in association with die casting of Mg alloys are discussed.Rapid assessment of Mg oxide and intermetallics relevant to sludge formation in Mg alloys are highlighted.展开更多
In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar ...In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar collision species alternated frequently between 9644 Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr.In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data,STAR developed a three-step blind analysis procedure.Analysts are initially provided a"reference sample"of data,comprised of a mix of events from the two species,the order of which respects time-dependent changes in run conditions.After tuning analysis codes and performing time-dependent quality assurance on the reference sample,analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual≈30-min data-taking runs.For this sample,species-specific information is disguised,but individual output files contain data from a single isobar species.Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage.Following these modifications,the"frozen"code is passed over the fully un-blind data,completing the blind analysis.As a check of the feasibility of the blind analysis procedure,analysts completed a"mock data challenge,"analyzing data from Au+Au collisions at√^(S)NN=27 Ge V,collected in 2018.The Au+Au data were prepared in the same manner intended for the isobar blind data.The details of the blind analysis procedure and results from the mock data challenge are presented.展开更多
The recent evolution in researeh on the magnetostrictive materials is briefly reviewed.A cotnpaboon of the relative preperties between bulk and thin film materialS, and theeNcts of addition of elements on the magnetic...The recent evolution in researeh on the magnetostrictive materials is briefly reviewed.A cotnpaboon of the relative preperties between bulk and thin film materialS, and theeNcts of addition of elements on the magnetic properties are alSo given.展开更多
Using the SG-III prototype laser at China Academy of Engineering Physics,Mianyang,we irradiated polystyrene(CH)samples with a thermal radiation drive,reaching conditions on the principal Hugoniot up to P≈1 TPa(10 Mba...Using the SG-III prototype laser at China Academy of Engineering Physics,Mianyang,we irradiated polystyrene(CH)samples with a thermal radiation drive,reaching conditions on the principal Hugoniot up to P≈1 TPa(10 Mbar),and away from the Hugoniot up to P≈300 GPa(3 Mbar).The response of each sample was measured with a velocity interferometry diagnostic to determine the material and shock velocity,and hence the conditions reached,and the reflectivity of the sample,from which changes in the conductivity can be inferred.By applying the selfimpedance mismatch technique with the measured velocities,the pressure and density of thermodynamic points away from the principal Hugoniot were determined.Our results show an unexpectedly large reflectivity at the highest shock pressures,while the off-Hugoniot points agree with previous work suggesting that shock-compressed CH conductivity is primarily temperature-dependent.展开更多
利用绝对地震定位方法(Hpyo2000)对青藏高原中部地区(32°N～36°N,90°E～93°E)于2016年6月至2017年6月期间发生的中小地震进行了重定位。与中国地震台网测定结果相比,定位后结果整体上更加聚集,水平位差距超过10km,...利用绝对地震定位方法(Hpyo2000)对青藏高原中部地区(32°N～36°N,90°E～93°E)于2016年6月至2017年6月期间发生的中小地震进行了重定位。与中国地震台网测定结果相比,定位后结果整体上更加聚集,水平位差距超过10km,深度上集中在0～8km范围内,这表明青藏高原内部上地壳构造活跃。2017年6月共发生8次3.0级以上地震,定位后的震中位置集中分布在格拉丹东附近。定位前后M<3.0的小地震的结果也显示明显的差异。为此,我们采用CAP(Cut and Paste)方法反演了M≥3.0地震的震源机制,结果显示其与地表构造性质较为吻合,青藏高原内部仍受到印度板块强烈的挤压作用。其中2017年6月格拉丹东附近发生的8次地震均为正断或走滑兼正断型,根据前人研究结果,猜测这是壳幔活动剧烈的地表响应。展开更多
This paper briefly introduces the characteristics of electron beam physical vapor depo-sition (EBPVD) technique and the whole process of preparing micro--layer compositelaminate. And several major influencing factors ...This paper briefly introduces the characteristics of electron beam physical vapor depo-sition (EBPVD) technique and the whole process of preparing micro--layer compositelaminate. And several major influencing factors are presented and discussed. It wasfound that residual gas pressure should be low enough to guarantee the unobstructedtransporfation of vapor steam and electron beam; the evaporation method and evapo-ration speed are up to the different vapor pressure deficit of compositions of raw mate-rials; and the substrate temperature could have great influence on the microstructureof the micro--layer laminates.展开更多
基金Meridian Lightweight Technologies Inc.,Strathroy,Ontario Canadathe University of Windsor,Windsor,Ontario,Canada for supporting this workpart of a large project funded by Meridian Lightweight Technologies,Inc.
文摘Intermetallic formation in sludge during magnesium(Mg)melting,holding and high pressure die casting practices is a very important issue.But,very often it is overlooked by academia,original equipment manufacturers(OEM),metal ingot producers and even die casters.The aim of this study was to minimize the intermetallic formation in Mg sludge via the optimization of the chemistry and process parameters.The Al8Mn5 intermetallic particles were identified by the microstructure analysis based on the Al and Mn ratio.The design of experiment(DOE)technique,Taguchi method,was employed to minimize the intermetallic formation in the sludge of Mg alloys with various chemical compositions of Al,Mn,Fe,and different process parameters,holding temperature and holding time.The sludge yield(SY)and intermetallic size(IS)was selected as two responses.The optimum combination of the levels in terms of minimizing the intermetallic formation were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,690℃ for the holding temperature and holding at 30 mins for the holding time,respectively.The best combination for smallest intermetallic size were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,630℃ for the holding temperature and holding at 60 mins for the holding time,respectively.Three groups of sludge factors,Chemical Sludge(CSF),Physical Sludge(PSF)and Comprehensive Sludge Factors(and CPSF)were established for prediction of sludge yields and intermetallic sizes in Al-containing Mg alloys.The CPSF with five independent variables including both chemical elements and process parameters gave high accuracy in prediction,as the prediction of the PSF with only the two processing parameters of the melt holding temperature and time showed a relatively large deviation from the experimental data.The Chemical Sludge Factor was primarily designed for small ingot producers and die casters with a limited melting and holding capacity,of which process parameters could be fixed easily.The Physical Sludge Factor could be used for mass production with a single type of Mg alloy,in which the chemistry fluctuation might be negligible.In large Mg casting suppliers with multiple melting and holding furnaces and a number of Mg alloys in production,the Comprehensive Sludge Factor should be implemented to diminish the sludge formation.
基金The Major State Research and Development Program of China (No. 2021YFB3701100, No. SQ2020YFF0405156)the National Natural Science Foundation of China (No.52171097, No. 51971020)+2 种基金Beijing Laboratory of Metallic Materials and Processing for Modern Transportationthe Fundamental Research Funds for the Central Universities(No. FRF-IC-20–08)“Dingxinbeike” Project(G20200001105) for the international communication。
文摘Inferior absolute strength and dissolution properties are the main bottlenecks for the widespread application of dissolvable magnesium alloys in complex working environments for unconventional oil and gas resources.Here,a novel functional peak-aged Mg-9.5Gd-2.7Y-0.9Zn-0.8Cu-0.4Ni(wt.%) alloy for fracturing tools is reported,and it possesses an ultimate tensile strength of 457.6 MPa,ultimate compressive strength of 620.7 MPa and dissolution rate of ~43.7 mg·cm^(-2)·h^(-1) in 3 wt.% KCl solutions at 93℃.The excellent strength of the agedalloy is primarily attributed to the combination of grain refinement,long-period stacking ordered(LPSO) strengthening,and precipitation strengthening induced by stacking fault and β’ phase,among which the precipitation strengthening is dominant.Further investigations confirm that the corrosion is triggered from the micro-galvanic coupling between the Mg matrix and the cathodic lamellar and block LPSO phases.Strip-shaped corrosion pits along with LPSO phases are subsequently formed,significantly accelerating corrosion.The β’ precipitates can effectively improve the strength without compromising the dissolution rate because of their nanoscale size.This study provides an excellent material selection for dissolvable fracturing tools and presents a strategy by which a synergistic combination of strength and dissolution rate is achieved via peak-aging treatment.
基金supported by the Einstein Probe project,a mission in the Strategic Priority Program on Space Science of CAS(grant Nos.XDA15310000,XDA15052100)in part been supported by the European Union’s Horizon 2020 Program under the AHEAD2020 project(grant No.871158).
文摘The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.
基金the Meridian Lightweight Technologies Inc., Strathroy, Ontario Canadathe University of Windsor, Windsor, Ontario, Canada for supporting this workpart of a large project funded by Meridian Lightweight Technologies, Inc.
文摘Sludge consisting of heavy element phases and oxides is often generated during the casting operation of aluminum(Al)and magnesium(Mg)alloys.With the help of the well-established Sludge Factor(SF)formula,it is relatively easy to control the sludge generation in aluminum alloys.But formation mechanisms and characteristics of sludge in die casting magnesium alloys are still unclear.To ensure the production of high quality die cast components at a low cost,a full understanding of sludge in die casting Mg alloys and its proper control measures need to be developed,since excessive sludge formation affects deleteriously material and operation cost,and casting performance.In the present report,the formation,characteristics and control of Mg die-casting sludge,based on the established knowledge of sludge formation and sludge factor in Al die casting alloys,are reviewed.Previous work on characterization and assessment of sludge in die cast Mg alloys are reviewed.Metallurgical principles for control of sludge in ingot production in association with die casting of Mg alloys are discussed.Rapid assessment of Mg oxide and intermetallics relevant to sludge formation in Mg alloys are highlighted.
文摘In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar collision species alternated frequently between 9644 Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr.In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data,STAR developed a three-step blind analysis procedure.Analysts are initially provided a"reference sample"of data,comprised of a mix of events from the two species,the order of which respects time-dependent changes in run conditions.After tuning analysis codes and performing time-dependent quality assurance on the reference sample,analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual≈30-min data-taking runs.For this sample,species-specific information is disguised,but individual output files contain data from a single isobar species.Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage.Following these modifications,the"frozen"code is passed over the fully un-blind data,completing the blind analysis.As a check of the feasibility of the blind analysis procedure,analysts completed a"mock data challenge,"analyzing data from Au+Au collisions at√^(S)NN=27 Ge V,collected in 2018.The Au+Au data were prepared in the same manner intended for the isobar blind data.The details of the blind analysis procedure and results from the mock data challenge are presented.
文摘The recent evolution in researeh on the magnetostrictive materials is briefly reviewed.A cotnpaboon of the relative preperties between bulk and thin film materialS, and theeNcts of addition of elements on the magnetic properties are alSo given.
基金The authors would like to thank the technical teams at LFRC for their invaluable work producing the targets and operating the facility.N.J.H.and D.K.were supported by the Helmholtz Association under Grant No.VH-NG-1141.Y.L.was supported by the National Natural Science Foundation of China(Grant No.11605189).
文摘Using the SG-III prototype laser at China Academy of Engineering Physics,Mianyang,we irradiated polystyrene(CH)samples with a thermal radiation drive,reaching conditions on the principal Hugoniot up to P≈1 TPa(10 Mbar),and away from the Hugoniot up to P≈300 GPa(3 Mbar).The response of each sample was measured with a velocity interferometry diagnostic to determine the material and shock velocity,and hence the conditions reached,and the reflectivity of the sample,from which changes in the conductivity can be inferred.By applying the selfimpedance mismatch technique with the measured velocities,the pressure and density of thermodynamic points away from the principal Hugoniot were determined.Our results show an unexpectedly large reflectivity at the highest shock pressures,while the off-Hugoniot points agree with previous work suggesting that shock-compressed CH conductivity is primarily temperature-dependent.
文摘利用绝对地震定位方法(Hpyo2000)对青藏高原中部地区(32°N～36°N,90°E～93°E)于2016年6月至2017年6月期间发生的中小地震进行了重定位。与中国地震台网测定结果相比,定位后结果整体上更加聚集,水平位差距超过10km,深度上集中在0～8km范围内,这表明青藏高原内部上地壳构造活跃。2017年6月共发生8次3.0级以上地震,定位后的震中位置集中分布在格拉丹东附近。定位前后M<3.0的小地震的结果也显示明显的差异。为此,我们采用CAP(Cut and Paste)方法反演了M≥3.0地震的震源机制,结果显示其与地表构造性质较为吻合,青藏高原内部仍受到印度板块强烈的挤压作用。其中2017年6月格拉丹东附近发生的8次地震均为正断或走滑兼正断型,根据前人研究结果,猜测这是壳幔活动剧烈的地表响应。
基金This work was supported by the Natural Science Foundation of Heilongjiang Province(No.E01-07)Postdoctoral Science Foundation of China(No.LB0047).
文摘This paper briefly introduces the characteristics of electron beam physical vapor depo-sition (EBPVD) technique and the whole process of preparing micro--layer compositelaminate. And several major influencing factors are presented and discussed. It wasfound that residual gas pressure should be low enough to guarantee the unobstructedtransporfation of vapor steam and electron beam; the evaporation method and evapo-ration speed are up to the different vapor pressure deficit of compositions of raw mate-rials; and the substrate temperature could have great influence on the microstructureof the micro--layer laminates.
