Mesoporous aluminaΥ-AI203 with high specific surface area and large pore volume is prepared by using a facile reverse precipitation method from sodium aluminate and nitric acid. The effects of terminal pH value, agin...Mesoporous aluminaΥ-AI203 with high specific surface area and large pore volume is prepared by using a facile reverse precipitation method from sodium aluminate and nitric acid. The effects of terminal pH value, aging time and thermal stability on the characterization of Υ-Al2Oa are studied by means of X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, Brunauer-Emmett-Teller （BET） method and scanning electron microscopy （SEM）. The results show that Υ-A1203 with better properties can be obtained by changing the preparation parameters. High BET surface area of 340 m2/g can be obtained by calcining at 500℃ for 4 h with large pore volume of 0.90 cm3/g and average pore size of 7.6 nm. After calcining at 1000°, the surface area is still 86 m2//g and the pore volume is 0.37 cm31/g.展开更多
The amorphous/amorphous nanolaminates(A/ANLs)have aroused great attentions owing to their tunable structure and enhanced mechanical properties.However,the plastic deformation mechanism of A/ANLs have yet been clarifie...The amorphous/amorphous nanolaminates(A/ANLs)have aroused great attentions owing to their tunable structure and enhanced mechanical properties.However,the plastic deformation mechanism of A/ANLs have yet been clarified.Here,we systematically examined the mechanical properties and deformation behavior of series of NiNb/ZrCuNi Al A/ANLs via nanoindentaion test.It was found that both the amount and morphology of amorphous/amorphous interface(A/AIs)played crucial roles in the plastic deformation of A/ANLs.Less and straighter A/AIs facilitated multiple shear banding deformation,of which the hardness increased with decreasing layer thickness,as the A/AIs hindered the propagation of shear bands(SBs).Whilst,more and wavier A/AIs promoted homogeneous deformation,of which the hardness stayed at a much lower value and was relatively irrelevant with the layer thickness,for the promoted activation of shear transformation zones by A/AIs.Our results provide guidance for modifying the mechanical properties of amorphous alloys with interface engineering design.展开更多
The plastic deformation of amorphous alloys is well known to be localized into shear bands(SBs),which are believed to stem from the atomic-scale flow defects,i.e.,shear transformation zones(STZs).Yet,the bridge betwee...The plastic deformation of amorphous alloys is well known to be localized into shear bands(SBs),which are believed to stem from the atomic-scale flow defects,i.e.,shear transformation zones(STZs).Yet,the bridge between the mesoscopic SBs and the atomic-scale STZs remains poorly understood.In this work,through thermally activating pronouncedβrelaxations in the well-designed crystalline-layer confined amorphous(CLCA)Ni W alloy films,we experimentally captured and observed an intermediate nanosized structure termed as“nano shear bands”(NSBs)with a typical size of 1–2 nm in thickness and5–10 nm in length.The influences of such NSB structures on the macroscale deformation behavior were systematically investigated.It was found that NSBs lead to both hardening and toughening effects for the CLCA films,as they promote multiple and controlled shear banding deformation,which results in enhanced crystallization.The intermediate NSB structure could connect the microstructural characteristics and macroscopic plasticity in amorphous alloys and may provide new insights for understanding the microscopic deformation mechanism of amorphous alloys as well as tuning/designing their properties.展开更多
The cooling rate during vitrification is critical for determining the mechanical properties of metallic glasses.However,the structural origin of the cooling rate effect on mechanical behaviors is unclear.In this work,...The cooling rate during vitrification is critical for determining the mechanical properties of metallic glasses.However,the structural origin of the cooling rate effect on mechanical behaviors is unclear.In this work,a systematical investigation of the cooling rate effect on the deformation mode,shear band nucleation,and nanoscale heterogeneous structure was conducted in three Fe-based metallic glasses.The brittle to ductile deformation transition was observed when increasing the cooling rate.Meanwhile,the governing shear band nucleation site from high load site to low load site appears the synchronous tran-sition.By studying the corresponding nanoscale heterogeneous structure,it was found that nanoscale viscoelastic transition from solid-like to liquid-like as increasing cooling rate enables ductile deformation.The current work not only reveals the nanoscale structural origin of the cooling rate effect on the de-formation behaviors,but also provides a new route to design ductile metallic glasses by freezing more nanoscale liquid-like regions during cooling.展开更多
基金supported by the National Natural Science Foundation of China under grant No.50804031the Science Department of Liaoning Province of China under grant No.20102166the Science Department of Shenyang City of China under grant No.F10-205-1-03
文摘Mesoporous aluminaΥ-AI203 with high specific surface area and large pore volume is prepared by using a facile reverse precipitation method from sodium aluminate and nitric acid. The effects of terminal pH value, aging time and thermal stability on the characterization of Υ-Al2Oa are studied by means of X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, Brunauer-Emmett-Teller （BET） method and scanning electron microscopy （SEM）. The results show that Υ-A1203 with better properties can be obtained by changing the preparation parameters. High BET surface area of 340 m2/g can be obtained by calcining at 500℃ for 4 h with large pore volume of 0.90 cm3/g and average pore size of 7.6 nm. After calcining at 1000°, the surface area is still 86 m2//g and the pore volume is 0.37 cm31/g.
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2021A1515010756,2019B1515130005)the Guangdong Major Project of Basic and Applied Basic Research,China(Grant No.2019B030302010)+5 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180266)the Basic Research Program of Nantong(No.JC2019083)the National Natural Science Foundation of China(No.51822107,11972037,52001269)the Fundamental Research Funds for the Central Universitiesthe National Key Research and Development Plan(Grant No.2018YFA0703603)the Strategic Priority Research Program of Chinese Academy of Sciences with Grant No.XDB30000000
文摘The amorphous/amorphous nanolaminates(A/ANLs)have aroused great attentions owing to their tunable structure and enhanced mechanical properties.However,the plastic deformation mechanism of A/ANLs have yet been clarified.Here,we systematically examined the mechanical properties and deformation behavior of series of NiNb/ZrCuNi Al A/ANLs via nanoindentaion test.It was found that both the amount and morphology of amorphous/amorphous interface(A/AIs)played crucial roles in the plastic deformation of A/ANLs.Less and straighter A/AIs facilitated multiple shear banding deformation,of which the hardness increased with decreasing layer thickness,as the A/AIs hindered the propagation of shear bands(SBs).Whilst,more and wavier A/AIs promoted homogeneous deformation,of which the hardness stayed at a much lower value and was relatively irrelevant with the layer thickness,for the promoted activation of shear transformation zones by A/AIs.Our results provide guidance for modifying the mechanical properties of amorphous alloys with interface engineering design.
基金financially supported by the Guangdong Major Project of Basic and Applied Basic ResearchChina(No.2019B030302010)+8 种基金the Guangdong Basic and Applied Basic Research FoundationChina(Nos.2021A1515010756,2019B1515130005)the Natural Science Foundation of Jiangsu ProvinceChina(No.BK20180266)the National Natural Science Foundation of China(Nos.51471131,52071222,51822107,11972037,52001269,52101199,52001219)the FundamentalResearch Funds for the Central Universitiesthe National Key Research and Development Plan(No.2018YFA0703603)the Strategic Priority Research Program of Chinese Academy of Sciences with Grant No.XDB30000000the Tianshan Innovation Team Program of Xinjiang Uygur Autonomous Region(No.2020D14038)。
文摘The plastic deformation of amorphous alloys is well known to be localized into shear bands(SBs),which are believed to stem from the atomic-scale flow defects,i.e.,shear transformation zones(STZs).Yet,the bridge between the mesoscopic SBs and the atomic-scale STZs remains poorly understood.In this work,through thermally activating pronouncedβrelaxations in the well-designed crystalline-layer confined amorphous(CLCA)Ni W alloy films,we experimentally captured and observed an intermediate nanosized structure termed as“nano shear bands”(NSBs)with a typical size of 1–2 nm in thickness and5–10 nm in length.The influences of such NSB structures on the macroscale deformation behavior were systematically investigated.It was found that NSBs lead to both hardening and toughening effects for the CLCA films,as they promote multiple and controlled shear banding deformation,which results in enhanced crystallization.The intermediate NSB structure could connect the microstructural characteristics and macroscopic plasticity in amorphous alloys and may provide new insights for understanding the microscopic deformation mechanism of amorphous alloys as well as tuning/designing their properties.
基金supported by the National Natural Science Foun-dation of China(Nos.52201194,52222105,52261028,52001269,92163108,52231006)the 3315 Innovation Youth Talent in Ningbo City(No.2021A123G)+3 种基金the Youth Innovation Promotion Association CAS(No.2019296)the Zhejiang Provincial Natural Science Foun-dation of China(No.LR22E010004)the Zhejiang Provincial Natu-ral Science Foundation Regional Innovation and Development Joint Foundation with Quzhou City(No.LZY23E010002)the Nat-ural Science Foundation of Xinjiang Uygur Autonomous Region of China(No.2022D01C383).
文摘The cooling rate during vitrification is critical for determining the mechanical properties of metallic glasses.However,the structural origin of the cooling rate effect on mechanical behaviors is unclear.In this work,a systematical investigation of the cooling rate effect on the deformation mode,shear band nucleation,and nanoscale heterogeneous structure was conducted in three Fe-based metallic glasses.The brittle to ductile deformation transition was observed when increasing the cooling rate.Meanwhile,the governing shear band nucleation site from high load site to low load site appears the synchronous tran-sition.By studying the corresponding nanoscale heterogeneous structure,it was found that nanoscale viscoelastic transition from solid-like to liquid-like as increasing cooling rate enables ductile deformation.The current work not only reveals the nanoscale structural origin of the cooling rate effect on the de-formation behaviors,but also provides a new route to design ductile metallic glasses by freezing more nanoscale liquid-like regions during cooling.
