Ti-47Al-2Nb-2Cr-0.4（W, Mo） （mole fraction, %） alloy ingot fabricated using vacuum consumable melting was containerless near-isothermally forged, and the high temperature forgeability, microstructure and tensile pr...Ti-47Al-2Nb-2Cr-0.4（W, Mo） （mole fraction, %） alloy ingot fabricated using vacuum consumable melting was containerless near-isothermally forged, and the high temperature forgeability, microstructure and tensile properties were investigated. The results show that the TiAl ingot exhibits good heat workability during containerless near-isothermally forging process, and there are not evident cracks on the surface of as-forged TiAl pancake with a total deformation degree of 60%. The microstructure of the TiAl ingot appears to be typical nearly-lamellar（NL）, comprising a great amount of lamellar colonies （α2＋γ） and a few equiaxed γ grains. After near-isothermally forging, the as-forged pancake shows primarily fine equiaxed γ grains with an average grain size of 20 μm and some broken lamellar pieces, and some bent lamellas still exist in the hard-deformation zone. Tensile tests at room temperature show that ultimate tensile strength increases from 433 MPa to 573 MPa after forging due to grain refinement effect.展开更多
Bulk LaO-GaO-ZrO(LGZ)glass and Tm/Ybco-doped LGZ glasses were synthesized successfully using containerless technique.Raman spectra result reveals that the matrix sample possesses the low maximum phonon energy of~642 c...Bulk LaO-GaO-ZrO(LGZ)glass and Tm/Ybco-doped LGZ glasses were synthesized successfully using containerless technique.Raman spectra result reveals that the matrix sample possesses the low maximum phonon energy of~642 cm.The glasses show good compatibility between large Abbe numbers(>31)and high refractive indices(n>1.93).Moreover,transmittance measurements reflect that the glasses have high infrared transmittance of-81.9%,small OHabsorption coefficient and long mid-infrared cut-off wavelengths(-7.5μm).The surface morphology of host glass was characterized by scanning electron microscopy(SEM)micrograph and energy dispersive spectroscopy(EDS)tests reflect that the doped compositions are distributed into the matrix glass homogeneously.The results of thermal analysis show that the glasses have good thermal properties(T>769℃).Excited by 980 am laser,an intense 1810 am fluorescence is obtained originating from the transition:~3 E→~3 Hof Tmion,accompanied by upconversion emission.It can be observed that 1810 nm fluorescence has the highest intensity at 1 mol%YbOand owns broad full width at half-maximum(>245 nm),the luminescence intensity of~3 F→~3 Htransition increases with rising temperature from 300 to 550 K.Furthermore,the value of energy transfer efficiency shows that Ybcan transfer energy to Tmeffectively.By fitting the attenuation curves,the lifetimes of 1810 and 474 nm emission can be acquired.展开更多
Biomaterial-induced mild alkaline microenvironments can positively affect osteoblast activity,contributing to bone regeneration.However,the challenge associated with silicate bioactive glasses,including melt-derived 4...Biomaterial-induced mild alkaline microenvironments can positively affect osteoblast activity,contributing to bone regeneration.However,the challenge associated with silicate bioactive glasses,including melt-derived 4555 Bioglass(4555-Glass)and sol-gel bioactive glasses,lies in the rapid release of cations in the early stage,resulting in a significant increase in the local pH,which could induce inflammatory reactions and even hinder the process of bone regeneration.Therefore,It is crucial to develop bloactive glass with mild alkaline capacity and a moderate release rate of bloactive ions.In this study,a novel class of bicactive glass(5P-Glass,CaTisiO_(5)glass)is fabricated via a containerless melting approach to avold phase separation and heterogeneous nucleation during the glass formation process.Compared with 4555-Glass,the network structure of SP-Glass is more stable,resulting in a significant reduction in the pH value and release rate of bioactive ions.SP-Glass creates a favorable mildly alkaline microenvironment for promoting the osteogenic differentiation of osteoblasts while inhibiting osteoclastic activity.Moreover,SP-Glass facilitates the shift of macrophages from the proinflammatory M1 state to the anti-inflammatory M2 state and promotes bone regeneration in vivo.Therefore,containerless melting-prepared bioactive glasses with mild alkalinity combine excellent biocompatibility and bone-forming bioactivity,representing a new class of bioactive materials for tissue regeneration.展开更多
Emulsions are inherently thermodynamically unstable dispersions that are widely involved in food processing,cosmetic preparation,and drug delivery.The existing ultrasonic emulsification techniques mainly rely on the d...Emulsions are inherently thermodynamically unstable dispersions that are widely involved in food processing,cosmetic preparation,and drug delivery.The existing ultrasonic emulsification techniques mainly rely on the direct contact between the sonicator probe and liquids,which causes localized high temperature and pressure within the liquid and influences the final properties of the obtained emulsion.In this work,a containerless emulsification approach has been realized by using ultrasonic levitation.The emulsification of water‒oil system can be promoted by adjusting the emitter‒reflector distance to alter the acoustic radiation pressure on the surface of the levitated drop.The dynamic behaviors of the emulsification process were monitored by using a high-speed camera,and the sound field was analyzed via numerical simu-lation.The experimental results showed that atomization of droplets driven by sound field was the main driving force for emulsification.This method can be used to pre-pare emulsions in which the average diameter of the droplets was about 2–3µm.The work provided a new method for containerless emulsification,thus shedding light on the preparation of contamination-free pharmaceuticals.展开更多
Droplets of Zr41Ti14Cu12.5Ni10Be22.5 glass forming alloys with different sizes are solidified in a drop tube containerless processing. Glass transition behavior, crystallization kinetics, and the phase evolution durin...Droplets of Zr41Ti14Cu12.5Ni10Be22.5 glass forming alloys with different sizes are solidified in a drop tube containerless processing. Glass transition behavior, crystallization kinetics, and the phase evolution during annealing of the Zr41Ti14Cu12.5Ni10Be22.5 glassy spheres are investigated. The experimental results indicate that the apparent activation energy of the glass transition (Eg=435.5 kJ/mol), and the activation energy of the main crystallization reaction (Ep1 = 249.6 kJ/mol) are obviously different from those of bulk glass samples prepared by water quenched (Eg=559.1 kJ/mol and Ep1=192.5 kJ/mol). The difference is discussed in the view point of the atomic configuration of the liquid state of the metallic glass and nucleation mechanism.展开更多
Ⅰ. SAMPLE PREPARATIONThe sample alloy used in this experiment was Pd<sub>40</sub>Ni<sub>40</sub>P<sub>20</sub>. The casting ingot prepared by arc melting was put into a quartz tube...Ⅰ. SAMPLE PREPARATIONThe sample alloy used in this experiment was Pd<sub>40</sub>Ni<sub>40</sub>P<sub>20</sub>. The casting ingot prepared by arc melting was put into a quartz tube. To suppress the heterogeneous nucleation the tube was filled up with B<sub>2</sub>O<sub>3</sub> flux. Between the wall of the quartz tube and B<sub>2</sub>O<sub>3</sub> flux the Ta tube was inserted to avoid reaction of the flux with quartz. The quartz tube was展开更多
Phase selection and microstructure evolution of the undercooled eutectic Ti-Si alloy were systematically investigated by the electromagnetic levitation method, and the maximum undercooling achieved was 318 K(0.2 TE). ...Phase selection and microstructure evolution of the undercooled eutectic Ti-Si alloy were systematically investigated by the electromagnetic levitation method, and the maximum undercooling achieved was 318 K(0.2 TE). The migration of the liquidsolid interface was in-situ detected by a high-speed camera system. When the undercooling is smaller than 140 K, the liquid-solid interface is smooth. Once the undercooling arrives at 230 K, the liquid-solid interface is irregular, which reflects the growth transition from the solute control to the combined controls of solute and thermal. The eutectic growth velocity increases as an exponential function of undercooling. The electromagnetic stirring effect makes it difficult to increase undercooling, but plays an important role in accelerating the eutectic reaction velocity at low and moderate undercoolings. Primary dendritic β-Ti phase appears in the solidified alloy from 63 to 176 K undercoolings, and the microstructure is completely composed of eutectic once the undercoolings increase up to 230 K. When the undercoolings exceed 273 K, the microstructure consists of uniformly distributed irregular eutectic. For the drop tube experiments, the microstructures composed of a large amount of dendritic α-Ti phase and eutectic phase are found in a wide range of diameters from 69 to 725 μm. As the decrease of diameter, the solubility of Si in the dendritic α-Ti phase dramatically increases from 6.80% to 10.73%, and the ratio of the area occupied by the dendritic α-Ti on a cross-section of solidified alloy obviously increases from 23.52% to 41.02%, which result from the combined effects of high undercooling and large cooling rate.展开更多
In this study,a series of Er^3+/Yb^3+co-doped Ca-Mg-Si glasses were prepared via the containerless processing.Phase composition and luminescent properties of the prepared materials were investigated through XRD and sp...In this study,a series of Er^3+/Yb^3+co-doped Ca-Mg-Si glasses were prepared via the containerless processing.Phase composition and luminescent properties of the prepared materials were investigated through XRD and spectrometry,and bioactivity,biocompatibility and cytotoxicity were evaluated.The XRD patterns indicated that akermanite(AKT)ceramic powders were completely transformed into the glassy phase(AKT-G,EYA)through the containerless processing,which exhibit upconversion luminescence,and the luminescence intensity increased with the increase of the doping amount of Er^3+ and Yb^3+.High amount of Yb^3+doping and existence of Ca^2+in glasses resulted in more intensive red-light emission.The SEM observation,combined with EDS analysis,and cell culture experiments showed that the as-prepared glasses were nontoxic,biocompatible and bioactive.All these results demonstrated that the containerless processing is a facile method for preparing homogeneous luminescent bioactive glasses.Furthermore,this luminescent Ca-Mg-Si glasses may be used as bone implant materials to study the in vivo distribution of degradation products of bone implants,which may be of great significance for the development and clinical application of new bone grafting materials.展开更多
Rapid solidification of Cu-Pb monotectic alloys has been accomplished during free fall in a 3 m drop tube. Both macrosegregated and uniformly dispersed structures are observed in Cu-40 wt pct Pb alloy droplets, wherea...Rapid solidification of Cu-Pb monotectic alloys has been accomplished during free fall in a 3 m drop tube. Both macrosegregated and uniformly dispersed structures are observed in Cu-40 wt pct Pb alloy droplets, whereas droplets of composition Cu-64 wt pct Pb exhibit only macrosegregation morphologies. The microstructures are strongly dependent on droplet size. The higher undercooling tends to facilitate liquid phase separation and results in more extensive macrosegregation in smaller droplets. There exists a pronounced tendency for the Pb-rich liquid to occupy the surface of the droplets of both compositions, resulting from the quite lower surface tension of the Pb-rich phase and causing a Pb-rich layer at the surface of the solidified droplet. The nucleation of monotectic cells in the Cu-40 wt pct Pb droplets with dispersed structures preferentially occurs at the droplet surface. A single nucleation event takes place more frequently as droplet size is reduced.展开更多
A new class of high-entropy oxide glasses 20LaO_(3/2)-20TiO_(2)-20NbO_(5/2)-20WO_(3)-20MO_(3/2)(M=B/Ga/In)were designed and successfully fabricated by aerodynamic containerless processing.The results show that one can...A new class of high-entropy oxide glasses 20LaO_(3/2)-20TiO_(2)-20NbO_(5/2)-20WO_(3)-20MO_(3/2)(M=B/Ga/In)were designed and successfully fabricated by aerodynamic containerless processing.The results show that one can control the properties and increase the functionality of glass by changing the type of M.The Vicker's hardness reaches the highest value of 6.45 GPa for glass M=B.The best thermal stability and the glass forming ability,measured using the glass-transition temperature T_(g) and the temperature gap ΔT respectively,are found in glass M=In,with T_(g)=740℃ and ΔT=72℃.The optical properties show that the as-prepared glasses exhibit good transparency and high refractive index.Especially for glass M=In,its transmittance reaches almost 78% from visible to IR region,and the value is nearly unchanged after electron beam irradiation,indicating good irradiation resistance of this high-entropy oxide glass.Furthermore,the glass M=In has the highest refractive index(n_(d)=2.46) and low wavelength dispersion(v_(d)=45.6).These results demonstrate that the conceptual design of high-entropy materials is adaptable to high performance oxide glasses,which should be promising host materials for optical applications such as smart phones with digital cameras and endoscopes.展开更多
基金Project (2011CB605505) supported by the National Basic Research Program of ChinaProject (2008AA03A233) supported by the National High-Tech Research and Development Program of China
文摘Ti-47Al-2Nb-2Cr-0.4（W, Mo） （mole fraction, %） alloy ingot fabricated using vacuum consumable melting was containerless near-isothermally forged, and the high temperature forgeability, microstructure and tensile properties were investigated. The results show that the TiAl ingot exhibits good heat workability during containerless near-isothermally forging process, and there are not evident cracks on the surface of as-forged TiAl pancake with a total deformation degree of 60%. The microstructure of the TiAl ingot appears to be typical nearly-lamellar（NL）, comprising a great amount of lamellar colonies （α2＋γ） and a few equiaxed γ grains. After near-isothermally forging, the as-forged pancake shows primarily fine equiaxed γ grains with an average grain size of 20 μm and some broken lamellar pieces, and some bent lamellas still exist in the hard-deformation zone. Tensile tests at room temperature show that ultimate tensile strength increases from 433 MPa to 573 MPa after forging due to grain refinement effect.
基金Project supported by the Youth Innovation Promotion Association,the Chinese Academy of Sciences(2020256)the Key Equipment Research Program,CAS(YJKYYQ20190008)+2 种基金the Science and Technology Committee of Shanghai(19142200400,20QA1410300)the National Natural Science Foundation of China(51602330,51472263)the Science and Technology Innovation Action Project of Science and Technology Committee of Shanghai(20511107400,19DZ1100703,20511107404)。
文摘Bulk LaO-GaO-ZrO(LGZ)glass and Tm/Ybco-doped LGZ glasses were synthesized successfully using containerless technique.Raman spectra result reveals that the matrix sample possesses the low maximum phonon energy of~642 cm.The glasses show good compatibility between large Abbe numbers(>31)and high refractive indices(n>1.93).Moreover,transmittance measurements reflect that the glasses have high infrared transmittance of-81.9%,small OHabsorption coefficient and long mid-infrared cut-off wavelengths(-7.5μm).The surface morphology of host glass was characterized by scanning electron microscopy(SEM)micrograph and energy dispersive spectroscopy(EDS)tests reflect that the doped compositions are distributed into the matrix glass homogeneously.The results of thermal analysis show that the glasses have good thermal properties(T>769℃).Excited by 980 am laser,an intense 1810 am fluorescence is obtained originating from the transition:~3 E→~3 Hof Tmion,accompanied by upconversion emission.It can be observed that 1810 nm fluorescence has the highest intensity at 1 mol%YbOand owns broad full width at half-maximum(>245 nm),the luminescence intensity of~3 F→~3 Htransition increases with rising temperature from 300 to 550 K.Furthermore,the value of energy transfer efficiency shows that Ybcan transfer energy to Tmeffectively.By fitting the attenuation curves,the lifetimes of 1810 and 474 nm emission can be acquired.
基金supported by the National K&D Program of China(No.2023YFB3813000)the National Natural Science Foundation of China(Nos.32225028 and 32130062)+1 种基金the Space Application System of China Manned Space Program(No.KJZ-YY-NCL05)the Shanghai Pilot Program for Basic Rescardh-Chinese Academy of Science,Shanghai Branch(No.JCYJ-SHFY-2022-003).
文摘Biomaterial-induced mild alkaline microenvironments can positively affect osteoblast activity,contributing to bone regeneration.However,the challenge associated with silicate bioactive glasses,including melt-derived 4555 Bioglass(4555-Glass)and sol-gel bioactive glasses,lies in the rapid release of cations in the early stage,resulting in a significant increase in the local pH,which could induce inflammatory reactions and even hinder the process of bone regeneration.Therefore,It is crucial to develop bloactive glass with mild alkaline capacity and a moderate release rate of bloactive ions.In this study,a novel class of bicactive glass(5P-Glass,CaTisiO_(5)glass)is fabricated via a containerless melting approach to avold phase separation and heterogeneous nucleation during the glass formation process.Compared with 4555-Glass,the network structure of SP-Glass is more stable,resulting in a significant reduction in the pH value and release rate of bioactive ions.SP-Glass creates a favorable mildly alkaline microenvironment for promoting the osteogenic differentiation of osteoblasts while inhibiting osteoclastic activity.Moreover,SP-Glass facilitates the shift of macrophages from the proinflammatory M1 state to the anti-inflammatory M2 state and promotes bone regeneration in vivo.Therefore,containerless melting-prepared bioactive glasses with mild alkalinity combine excellent biocompatibility and bone-forming bioactivity,representing a new class of bioactive materials for tissue regeneration.
基金National Natural Science Foundation of China,Grant/Award Numbers:12272314,11972303State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Grant/Award Number:SKLSP202001。
文摘Emulsions are inherently thermodynamically unstable dispersions that are widely involved in food processing,cosmetic preparation,and drug delivery.The existing ultrasonic emulsification techniques mainly rely on the direct contact between the sonicator probe and liquids,which causes localized high temperature and pressure within the liquid and influences the final properties of the obtained emulsion.In this work,a containerless emulsification approach has been realized by using ultrasonic levitation.The emulsification of water‒oil system can be promoted by adjusting the emitter‒reflector distance to alter the acoustic radiation pressure on the surface of the levitated drop.The dynamic behaviors of the emulsification process were monitored by using a high-speed camera,and the sound field was analyzed via numerical simu-lation.The experimental results showed that atomization of droplets driven by sound field was the main driving force for emulsification.This method can be used to pre-pare emulsions in which the average diameter of the droplets was about 2–3µm.The work provided a new method for containerless emulsification,thus shedding light on the preparation of contamination-free pharmaceuticals.
基金This work was supportedby the National Natural Science Foundation of China (Grant Nos. 59889102, 10004014 and 50171077).
文摘Droplets of Zr41Ti14Cu12.5Ni10Be22.5 glass forming alloys with different sizes are solidified in a drop tube containerless processing. Glass transition behavior, crystallization kinetics, and the phase evolution during annealing of the Zr41Ti14Cu12.5Ni10Be22.5 glassy spheres are investigated. The experimental results indicate that the apparent activation energy of the glass transition (Eg=435.5 kJ/mol), and the activation energy of the main crystallization reaction (Ep1 = 249.6 kJ/mol) are obviously different from those of bulk glass samples prepared by water quenched (Eg=559.1 kJ/mol and Ep1=192.5 kJ/mol). The difference is discussed in the view point of the atomic configuration of the liquid state of the metallic glass and nucleation mechanism.
基金Project supported by the Electron Microscope Laboratory, Academia Sinica.
文摘Ⅰ. SAMPLE PREPARATIONThe sample alloy used in this experiment was Pd<sub>40</sub>Ni<sub>40</sub>P<sub>20</sub>. The casting ingot prepared by arc melting was put into a quartz tube. To suppress the heterogeneous nucleation the tube was filled up with B<sub>2</sub>O<sub>3</sub> flux. Between the wall of the quartz tube and B<sub>2</sub>O<sub>3</sub> flux the Ta tube was inserted to avoid reaction of the flux with quartz. The quartz tube was
基金supported by the National Key R&D Program of China(Grant No. 2018YFB2001800)the National Natural Science Foundation of China (Grant Nos. 51734008, 51771154, and 52088101)。
文摘Phase selection and microstructure evolution of the undercooled eutectic Ti-Si alloy were systematically investigated by the electromagnetic levitation method, and the maximum undercooling achieved was 318 K(0.2 TE). The migration of the liquidsolid interface was in-situ detected by a high-speed camera system. When the undercooling is smaller than 140 K, the liquid-solid interface is smooth. Once the undercooling arrives at 230 K, the liquid-solid interface is irregular, which reflects the growth transition from the solute control to the combined controls of solute and thermal. The eutectic growth velocity increases as an exponential function of undercooling. The electromagnetic stirring effect makes it difficult to increase undercooling, but plays an important role in accelerating the eutectic reaction velocity at low and moderate undercoolings. Primary dendritic β-Ti phase appears in the solidified alloy from 63 to 176 K undercoolings, and the microstructure is completely composed of eutectic once the undercoolings increase up to 230 K. When the undercoolings exceed 273 K, the microstructure consists of uniformly distributed irregular eutectic. For the drop tube experiments, the microstructures composed of a large amount of dendritic α-Ti phase and eutectic phase are found in a wide range of diameters from 69 to 725 μm. As the decrease of diameter, the solubility of Si in the dendritic α-Ti phase dramatically increases from 6.80% to 10.73%, and the ratio of the area occupied by the dendritic α-Ti on a cross-section of solidified alloy obviously increases from 23.52% to 41.02%, which result from the combined effects of high undercooling and large cooling rate.
文摘In this study,a series of Er^3+/Yb^3+co-doped Ca-Mg-Si glasses were prepared via the containerless processing.Phase composition and luminescent properties of the prepared materials were investigated through XRD and spectrometry,and bioactivity,biocompatibility and cytotoxicity were evaluated.The XRD patterns indicated that akermanite(AKT)ceramic powders were completely transformed into the glassy phase(AKT-G,EYA)through the containerless processing,which exhibit upconversion luminescence,and the luminescence intensity increased with the increase of the doping amount of Er^3+ and Yb^3+.High amount of Yb^3+doping and existence of Ca^2+in glasses resulted in more intensive red-light emission.The SEM observation,combined with EDS analysis,and cell culture experiments showed that the as-prepared glasses were nontoxic,biocompatible and bioactive.All these results demonstrated that the containerless processing is a facile method for preparing homogeneous luminescent bioactive glasses.Furthermore,this luminescent Ca-Mg-Si glasses may be used as bone implant materials to study the in vivo distribution of degradation products of bone implants,which may be of great significance for the development and clinical application of new bone grafting materials.
基金Financial support from the National Natural Science Founda tion of China(No.59871040 and 50071009)is gratefuly acknowledged.
文摘Rapid solidification of Cu-Pb monotectic alloys has been accomplished during free fall in a 3 m drop tube. Both macrosegregated and uniformly dispersed structures are observed in Cu-40 wt pct Pb alloy droplets, whereas droplets of composition Cu-64 wt pct Pb exhibit only macrosegregation morphologies. The microstructures are strongly dependent on droplet size. The higher undercooling tends to facilitate liquid phase separation and results in more extensive macrosegregation in smaller droplets. There exists a pronounced tendency for the Pb-rich liquid to occupy the surface of the droplets of both compositions, resulting from the quite lower surface tension of the Pb-rich phase and causing a Pb-rich layer at the surface of the solidified droplet. The nucleation of monotectic cells in the Cu-40 wt pct Pb droplets with dispersed structures preferentially occurs at the droplet surface. A single nucleation event takes place more frequently as droplet size is reduced.
基金Project supported by the National Natural Science Foundation of China (51972048)the Fundamental Research Funds for the Central Universities (N2123003)。
文摘A new class of high-entropy oxide glasses 20LaO_(3/2)-20TiO_(2)-20NbO_(5/2)-20WO_(3)-20MO_(3/2)(M=B/Ga/In)were designed and successfully fabricated by aerodynamic containerless processing.The results show that one can control the properties and increase the functionality of glass by changing the type of M.The Vicker's hardness reaches the highest value of 6.45 GPa for glass M=B.The best thermal stability and the glass forming ability,measured using the glass-transition temperature T_(g) and the temperature gap ΔT respectively,are found in glass M=In,with T_(g)=740℃ and ΔT=72℃.The optical properties show that the as-prepared glasses exhibit good transparency and high refractive index.Especially for glass M=In,its transmittance reaches almost 78% from visible to IR region,and the value is nearly unchanged after electron beam irradiation,indicating good irradiation resistance of this high-entropy oxide glass.Furthermore,the glass M=In has the highest refractive index(n_(d)=2.46) and low wavelength dispersion(v_(d)=45.6).These results demonstrate that the conceptual design of high-entropy materials is adaptable to high performance oxide glasses,which should be promising host materials for optical applications such as smart phones with digital cameras and endoscopes.
