A simple analytic modified embedded atom method (M EAM ) Inciuding a modified term for hcp metals has been developed from the MEAM applied to the fcc and bcc metals. The enthalpiesof formation of all binary alloy syst...A simple analytic modified embedded atom method (M EAM ) Inciuding a modified term for hcp metals has been developed from the MEAM applied to the fcc and bcc metals. The enthalpiesof formation of all binary alloy systems for eight transition hcp metals are calculated with theMEAM. The calculations are in agreement with the experimental data avallable and resultscalculated from the Miedema theory. One can conclude that our MEAM is also effective toapply to the hcp metals and their alloys.展开更多
A simple analytic embedded-atom model of monoatoms that includes more than nearest neighbours has been extended to study properties of binary liquid Cu-Ni alloys, here the two-body potential between different species ...A simple analytic embedded-atom model of monoatoms that includes more than nearest neighbours has been extended to study properties of binary liquid Cu-Ni alloys, here the two-body potential between different species of atoms is taken as a function of the two-body potential for the pure metals with a unique form which yields alloy models with the same invariance to electron density transformations as monoatomic models. Faber-Ziman structure factors have been computed by molecular dynamics simulation on the base of this model. The results are in good agreement with experimental data given by Waseda, thus supporting the overall validity of the approach, especially for cross potential of Cu-Ni pair. Further, a detailed description of structure of binary liquid Cu-Ni alloys with different compositions have been performed using pair analysis and bond orientational order method etc., and then the chemical short range order has also been examined to reveal the structural characterization.展开更多
The surface energy values of (100), (110), (111) surfaces in Ni. Al and ordered alloys NiAl and Ni3Al have been calculated within the framework of methodology based upon the electron density functional method. The res...The surface energy values of (100), (110), (111) surfaces in Ni. Al and ordered alloys NiAl and Ni3Al have been calculated within the framework of methodology based upon the electron density functional method. The results of calculations are in good agreement with the known for pure metals experimental data and in case of Ni3Al allop There is also a good agreement with the results obtained by calculation using the embedded atom method. The investigation has been carried out in this work to show that the surface energy σ of alloys can not be interpreted as an averaged concentration σ of pure metals. For NiAl, the obtained resulsts reveal considerable distinctions in anisotropy of a in comparison to the anisotropy of surface energy in pure matals.展开更多
The nano-crystalline materials with many special and super magnetic properties could be synthesized by fractional crystallization of amorphous alloys. Since this new method for preparation of nano-crystalline material...The nano-crystalline materials with many special and super magnetic properties could be synthesized by fractional crystallization of amorphous alloys. Since this new method for preparation of nano-crystalline materials was introduced, the crystallization kinetics of amorphous alloys has been studied in more and more intensive investigations. So far, almost all experiments on the crystallization kinetics are conducted by differential展开更多
Post-sinter annealing process plays an important role in the microstructures and magnetic properties of the Nd-Fe-B sintered magnets.In this paper,systematically investigated are the magnetic properties and microstruc...Post-sinter annealing process plays an important role in the microstructures and magnetic properties of the Nd-Fe-B sintered magnets.In this paper,systematically investigated are the magnetic properties and microstructures of the as-sintered and post-sinter annealed Nd-Fe-B magnets with Pr-Fe-Ga boundary addition.Two choice consecutive annealing methods are adopted at high and low temperatures,namely the 1 st annealing at 880℃ for 2 h and then the 2^(nd) annealing at 440℃ for 3 h.It is exceptional to find out that both the remanence and coercivity are improved after 2^(nd) annealing process for this type of magnet.The coercivity is hugely increased from 10.09 kOe for the as-sintered sample to 17.19 kOe for the 2^(nd) annealed magnet,with a significant increment of 70.37%in coercivity.The extraordinary magnetic properties of B_(r)=14.44 kGs,H_(cj)=17.19 kOe and(BH)_(max)=51.08 MGOe are obtained for the designated Nd-Fe-B sintered magnets without heavy rare earth(HRE)elements manufactured by dual alloy method.The Curie temperature is monotonically decreased from 634 K to 602 K while the c-axis alignment degree is optimized after annealing.Microstructural observation and analysis indicate that the elemental distribution patterns are altered after the 2^(nd) annealing.The diffusion of the aggregate(Pr,Nd,Cu,Ga)-rich phase from triple junctions into the grain boundary regions is ascribed to the formation of thin and continuous grain boundary layer,which is critical to improve the microstructures and magnetic properties.展开更多
Sodium-ion batteries are considered as a promising low-cost alternative to commercial lithium-ion batteries.However,the harsh preparation conditions and unsatisfactory electrochemical performance of most sodium-ion ba...Sodium-ion batteries are considered as a promising low-cost alternative to commercial lithium-ion batteries.However,the harsh preparation conditions and unsatisfactory electrochemical performance of most sodium-ion batteries anode materials limit their commercial applications.Herein,we develop a new alloying/dealloying method for producing nano-scale tin from freezing point to room temperature.Due to the unique surface properties of tin particles,a tin/carbon composite with a compact structure is obtained.When coupled with a diglyme-based electrolyte,tin/carbon composite(contains 60 wt.%tin)exhibits a reversible capacity of 334.8 mAh·g^(−1)after 1,000 cycles at 500 mA·g^(−1).An as-prepared tin/carbon anode||high-load vanadium phosphate sodium full cell(N/P ratio:1.07)shows a stable cycle life of 300 cycles at 1 A·g^(−1).The achievement of such an excellent performance can be ascribed to the carbon conductive network and robust solid electrolyte interphase film,which facilitates the fast transportation of electrons and Na ions.This work provides a new idea to prepare other alloyed anode materials for highperformance sodium-ion batteries.展开更多
文摘A simple analytic modified embedded atom method (M EAM ) Inciuding a modified term for hcp metals has been developed from the MEAM applied to the fcc and bcc metals. The enthalpiesof formation of all binary alloy systems for eight transition hcp metals are calculated with theMEAM. The calculations are in agreement with the experimental data avallable and resultscalculated from the Miedema theory. One can conclude that our MEAM is also effective toapply to the hcp metals and their alloys.
文摘A simple analytic embedded-atom model of monoatoms that includes more than nearest neighbours has been extended to study properties of binary liquid Cu-Ni alloys, here the two-body potential between different species of atoms is taken as a function of the two-body potential for the pure metals with a unique form which yields alloy models with the same invariance to electron density transformations as monoatomic models. Faber-Ziman structure factors have been computed by molecular dynamics simulation on the base of this model. The results are in good agreement with experimental data given by Waseda, thus supporting the overall validity of the approach, especially for cross potential of Cu-Ni pair. Further, a detailed description of structure of binary liquid Cu-Ni alloys with different compositions have been performed using pair analysis and bond orientational order method etc., and then the chemical short range order has also been examined to reveal the structural characterization.
文摘The surface energy values of (100), (110), (111) surfaces in Ni. Al and ordered alloys NiAl and Ni3Al have been calculated within the framework of methodology based upon the electron density functional method. The results of calculations are in good agreement with the known for pure metals experimental data and in case of Ni3Al allop There is also a good agreement with the results obtained by calculation using the embedded atom method. The investigation has been carried out in this work to show that the surface energy σ of alloys can not be interpreted as an averaged concentration σ of pure metals. For NiAl, the obtained resulsts reveal considerable distinctions in anisotropy of a in comparison to the anisotropy of surface energy in pure matals.
文摘The nano-crystalline materials with many special and super magnetic properties could be synthesized by fractional crystallization of amorphous alloys. Since this new method for preparation of nano-crystalline materials was introduced, the crystallization kinetics of amorphous alloys has been studied in more and more intensive investigations. So far, almost all experiments on the crystallization kinetics are conducted by differential
基金supported by the National Natural Science Foundation of China(Grant Nos.51901089 and 52061015)the Key Research and Development Program of Jiangxi Province(No.20201BBE51010)+2 种基金China Postdoctoral Science foundation(Grant No.2020M682064)Postdoctoral Science foundation of Jiangxi Province(Grant No.2020KY19)the Program of Qingjiang Excellent Young Talents of Jiangxi University of Science and Technology(No.JXUSTQJYX2020003)。
文摘Post-sinter annealing process plays an important role in the microstructures and magnetic properties of the Nd-Fe-B sintered magnets.In this paper,systematically investigated are the magnetic properties and microstructures of the as-sintered and post-sinter annealed Nd-Fe-B magnets with Pr-Fe-Ga boundary addition.Two choice consecutive annealing methods are adopted at high and low temperatures,namely the 1 st annealing at 880℃ for 2 h and then the 2^(nd) annealing at 440℃ for 3 h.It is exceptional to find out that both the remanence and coercivity are improved after 2^(nd) annealing process for this type of magnet.The coercivity is hugely increased from 10.09 kOe for the as-sintered sample to 17.19 kOe for the 2^(nd) annealed magnet,with a significant increment of 70.37%in coercivity.The extraordinary magnetic properties of B_(r)=14.44 kGs,H_(cj)=17.19 kOe and(BH)_(max)=51.08 MGOe are obtained for the designated Nd-Fe-B sintered magnets without heavy rare earth(HRE)elements manufactured by dual alloy method.The Curie temperature is monotonically decreased from 634 K to 602 K while the c-axis alignment degree is optimized after annealing.Microstructural observation and analysis indicate that the elemental distribution patterns are altered after the 2^(nd) annealing.The diffusion of the aggregate(Pr,Nd,Cu,Ga)-rich phase from triple junctions into the grain boundary regions is ascribed to the formation of thin and continuous grain boundary layer,which is critical to improve the microstructures and magnetic properties.
基金supported by the National Natural Science Foundation of China(Nos.51972351 and 51802361)Guangdong Basic and Applied Basic Research Foundation(No.2019B151502045).
文摘Sodium-ion batteries are considered as a promising low-cost alternative to commercial lithium-ion batteries.However,the harsh preparation conditions and unsatisfactory electrochemical performance of most sodium-ion batteries anode materials limit their commercial applications.Herein,we develop a new alloying/dealloying method for producing nano-scale tin from freezing point to room temperature.Due to the unique surface properties of tin particles,a tin/carbon composite with a compact structure is obtained.When coupled with a diglyme-based electrolyte,tin/carbon composite(contains 60 wt.%tin)exhibits a reversible capacity of 334.8 mAh·g^(−1)after 1,000 cycles at 500 mA·g^(−1).An as-prepared tin/carbon anode||high-load vanadium phosphate sodium full cell(N/P ratio:1.07)shows a stable cycle life of 300 cycles at 1 A·g^(−1).The achievement of such an excellent performance can be ascribed to the carbon conductive network and robust solid electrolyte interphase film,which facilitates the fast transportation of electrons and Na ions.This work provides a new idea to prepare other alloyed anode materials for highperformance sodium-ion batteries.
