Magnesium and magnesium alloy foils have great potential for application in battery anodes,electromagnetic shielding,optics and acoustics,and biology because of their excellent specific damping,internal dissipation co...Magnesium and magnesium alloy foils have great potential for application in battery anodes,electromagnetic shielding,optics and acoustics,and biology because of their excellent specific damping,internal dissipation coefficients,magnetic and electrical conductivities,as well as high theoretical specific capacity.However,magnesium alloys exhibit poor deformation ability due to their hexagonal close-packed crystal structure.Preparing magnesium and magnesium alloy foils with thicknesses of less than 0.1 mm is difficult because of surface oxidation and grain growth at high temperatures or severe anisotropy after cold rolling that leads to cracks.Numerous methods have been applied to prepare magnesium alloy foils.They include warm rolling,cold rolling,accumulative roll bonding,electric plastic rolling,and on-line heating rolling.Defects of magnesium and magnesium alloy foils during preparation,such as edge cracks and breakage,are important factors for consideration.Herein,the current status of the research on magnesium and magnesium alloy foils is summarized from the aspects of foil preparation,defect control,performance characterization,and application prospects.The advantages and disadvantages of different preparation methods and defect(edge cracks and breakage)mechanisms in the preparation of foils are identified.展开更多
The connection characteristics of rapidly solidified Cu-40%Co alloy foils were studied using a self-developed micro-type energy-storage welding machine. The results show that the microstructure of the alloy foils is c...The connection characteristics of rapidly solidified Cu-40%Co alloy foils were studied using a self-developed micro-type energy-storage welding machine. The results show that the microstructure of the alloy foils is characterized by uni form and fine equiaxed grains,whose maximum grain size is 1.8 μm. Under the o ptimum energy,the regular flat nugget is formed,low voltage and high capacitan ce are favorable for obtaining the perfect connection joints,whereas high volta ge and low capacitance are likely to result in the surface burn of the alloy foi ls. With the increase of welding energy,the spot welding joint will be transfor med from regular flat nugget to nugget-free one,and the microstructure tends t o coarsen. The welding parameters recommended are: welding voltage 80100 V,(electric) capacitance 1 8002 500 μF,and welding force 48 N.展开更多
Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulp...Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulphate and saccharin concentration on composition and current efficiency were investigated in detail. The morphology and the microstructure of deposits were analyzed by SEM and XRD, respectively. The results indicated that the optimum parameters were current density 3-4 A/dm2, pH 2-3, temperature 40-50?C, cobalt sulphate 20 g/l and saccharin 2-3 g/l. Chemical analysis of the deposits by EDS revealed anomalous Ni-Co codeposition occured in this system. The SEM showed that hydroxide particles were not present on the surface and that fine-grain, smooth and compact Ni-Co alloy deposits were obtained. The crystallographic structures of Ni-Co alloy foils were the fcc Ni solid solution. The Ni-Co alloy foils with Co content 17.3-37.2 wt% and thickness of 20-45 μm were bright with low residual stress and super toughness.展开更多
An alternative to conventional process for the preparation of soft magnetic metal foils of Fe,Fe-Ni,Fe-Co and Fe-Ni-Co by electroforming was described.The microstructure and magnetic properties were observed.The resul...An alternative to conventional process for the preparation of soft magnetic metal foils of Fe,Fe-Ni,Fe-Co and Fe-Ni-Co by electroforming was described.The microstructure and magnetic properties were observed.The results showed that the crystal size of the iron-based alloy foil is less than 10μm,while that of nickel-based alloy foil is about 2μm.Moreover,the electroformed Fe-Ni foil has better magnetic properties than the conventional milled permalloy 1J79 foil.展开更多
The microstructure evolution of the melt-spun Mg–7Y–4Gd–5Zn–0.4Zr alloy during annealing treatment has been investigated by using X-ray diffraction(XRD),optical microscope(OM),differential scanning calorimetry(DSC...The microstructure evolution of the melt-spun Mg–7Y–4Gd–5Zn–0.4Zr alloy during annealing treatment has been investigated by using X-ray diffraction(XRD),optical microscope(OM),differential scanning calorimetry(DSC)and transmission electron microscope(TEM).The results indicated that two kinds of primary grains were contained in the melt-spun alloy.One was the supersaturated magnesium matrix,and the other was the 18R-LPSO phase.The 18R-LPSO phase transformed into the 14H-LPSO phase during annealing treatment at 300 ℃ for 0.5 h.The new precipitate of the 14H-LPSO phase was found at 300 ℃ for 5 h.Lots of linear precipitates formed as well as some precipitate with quadrangular morphology in matrix at 500 ℃ for 0.5 h.The melt-spun alloy displayed the highest hardness of 103 NHV after annealing treatment at 300 ℃ for 5 h.展开更多
Microstructure and subsequent phase transformations on heating of the melt-spun Nd85Al15 alloy have been studied by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The melt-s...Microstructure and subsequent phase transformations on heating of the melt-spun Nd85Al15 alloy have been studied by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The melt-spun Nd85Al15 alloy shows two-stage transformation processes as follows: amorphous+72 nm supersaturated bcc-Nd(AI) solid solution-7 nm omega-like phase-AINd3+hexagonal Nd. The activation energies for the first and second transformation were found to be 100 kj/mol and 188 kj/mol, respectively. The formation mechanism of nanoscale omega-like phase is discussed.展开更多
Scanning electron microscopy and X-ray energy dispersive spectrum analysis show that the clusters of intermetallic AlFeSi particle are distributed on or near the aluminum foil stock surfaces heterogeneously. 3D finite...Scanning electron microscopy and X-ray energy dispersive spectrum analysis show that the clusters of intermetallic AlFeSi particle are distributed on or near the aluminum foil stock surfaces heterogeneously. 3D finite element modeling shows that these clusters of hard particles induce the fracture of the nano-scale lubricant oil film at first and further lead to severe deformation in the nearby aluminum foil substrate along the rolling direction. Consequently, the optical property in this region differs from that in the surroundings, resulting in surface defects.展开更多
The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile...The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10^-4s^-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are： T = 1273-1323K, p = 20-30MPa, t = 45-60min.展开更多
The effects of Co as a substituent for Ni on microstructure and electrochemical capacity of hydrogen storage alloys MI（NiCoMnAl）5.4 at -30- ＋80 ℃, in which the content of Co was 0, 1.31%, 2.63%, 3.94%, 5.25%, and ...The effects of Co as a substituent for Ni on microstructure and electrochemical capacity of hydrogen storage alloys MI（NiCoMnAl）5.4 at -30- ＋80 ℃, in which the content of Co was 0, 1.31%, 2.63%, 3.94%, 5.25%, and 6.56% （mass fraction）, respectively, were reported. All of the alloys were prepared by vacuum induction melting followed by melt-spinning. It is found that the electrochemical capacity of alloys at different temperature depends upon the compositions and preparation methods. The electrochemical capacity of alloys increases at higher temperature （40 - 80 ℃ ） and decreases at lower temperature （ - 30 - 0 ℃ ） with an increasing cobalt content. With an increasing temperature, melt-spinning is more favorable for improved capacity of the alloys than casting. Analyses of the charging/discharging potential curves illustrate that higher cobalt content and melt-spinning techniques are more effective to increase the capacity at higher temperature because of the higher hydrogen evolution potential. On the contrary, the capacity of alloys at lower temperature can be increased by decreasing cobalt content and casting, which is ascribed to higher hydrogen evolution potential and delayed hydrogen evolution reaction, as well as reduced potential drop in the charging/discharging process. XRD patterns confirm that all of the specimens present a single hexagonal CaCu5-type structure and an increased lattice parameters with increasing Co content. The FWHM of the main peak of melt-spun ribbons reduces because of more homogeneous composition and less lattice strain defects.展开更多
AA8079 is a commonly used stock material for manufacturing thin packaging foils.The primary alloying elements Fe and Si can form binary and tertiary intermetallics.In-situ TEM simulating homogenization annealing proce...AA8079 is a commonly used stock material for manufacturing thin packaging foils.The primary alloying elements Fe and Si can form binary and tertiary intermetallics.In-situ TEM simulating homogenization annealing process of the as-cast material was used to analyze the real-time changes of the shape,type,and distribution of these particles.They affect the mechanical properties of the final product and susceptibility of the material to the formation of pinholes and other macroscopic defects.Another set of as-cast samples were annealed in a regime simulating industrial treatment in combination with measurements of resistivity to validate the results of the in-situ experiment.The results show clear temperature intervals of recovery,matrix desaturation,and phase transformations occurring in several stages:spheroidization of the original particles above 450℃,nucleation of new particles at 475℃,particles coarsening above 525℃,and an entire dissolution of the original particles above 550℃.展开更多
Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin Fe Co-V foils were studied. Detailed data about the boundaries, coincidence site lattice（CSL） relati...Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin Fe Co-V foils were studied. Detailed data about the boundaries, coincidence site lattice（CSL） relationships, grain sizes, and microstructural features were acquired from electron-backscatter diffraction（EBSD） maps. Moreover, the evolution of the magnetic properties during high-energy-beam welding was studied using vibrating sample magnetometry（VSM）. The fraction of low-angle boundaries was observed to increase in the fusion zones of both electron- and laser-beam-welded foils. The results showed that the fractions of low-Σ CSL boundaries（particularly twin boundaries, Σ3） in the fusion zones of the welded foils are higher than those in the base metal. Because the strain rates produced during high-energy-beam welding are very high（because of the extremely high cooling rate）, grain deformation by a slip mechanism is limited; therefore, deformation by grain twinning is dominant. VSM analysis showed that the magnetic properties of the welded foils, i.e., their remanence, coercive force, and energy product, changed significantly. The formation of large grains with preferred orientation parallel to the easy axis of magnetization was the main reason for the diminished magnetic properties.展开更多
基金financially supported by the National Key Research and Development Program of China(Nos.2022 YFB3709300 and 2021YFB3701000)the National Natural Science Foundation of China(Nos.52271090 and 52071036)+1 种基金the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030006)the Independent Research Project of State Key Laboratory of Mechanical Transmissions(Nos.SKLMT-ZZKT-2022Z01 and S KLMT-ZZKT-2022M12)。
文摘Magnesium and magnesium alloy foils have great potential for application in battery anodes,electromagnetic shielding,optics and acoustics,and biology because of their excellent specific damping,internal dissipation coefficients,magnetic and electrical conductivities,as well as high theoretical specific capacity.However,magnesium alloys exhibit poor deformation ability due to their hexagonal close-packed crystal structure.Preparing magnesium and magnesium alloy foils with thicknesses of less than 0.1 mm is difficult because of surface oxidation and grain growth at high temperatures or severe anisotropy after cold rolling that leads to cracks.Numerous methods have been applied to prepare magnesium alloy foils.They include warm rolling,cold rolling,accumulative roll bonding,electric plastic rolling,and on-line heating rolling.Defects of magnesium and magnesium alloy foils during preparation,such as edge cracks and breakage,are important factors for consideration.Herein,the current status of the research on magnesium and magnesium alloy foils is summarized from the aspects of foil preparation,defect control,performance characterization,and application prospects.The advantages and disadvantages of different preparation methods and defect(edge cracks and breakage)mechanisms in the preparation of foils are identified.
文摘The connection characteristics of rapidly solidified Cu-40%Co alloy foils were studied using a self-developed micro-type energy-storage welding machine. The results show that the microstructure of the alloy foils is characterized by uni form and fine equiaxed grains,whose maximum grain size is 1.8 μm. Under the o ptimum energy,the regular flat nugget is formed,low voltage and high capacitan ce are favorable for obtaining the perfect connection joints,whereas high volta ge and low capacitance are likely to result in the surface burn of the alloy foi ls. With the increase of welding energy,the spot welding joint will be transfor med from regular flat nugget to nugget-free one,and the microstructure tends t o coarsen. The welding parameters recommended are: welding voltage 80100 V,(electric) capacitance 1 8002 500 μF,and welding force 48 N.
文摘Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulphate and saccharin concentration on composition and current efficiency were investigated in detail. The morphology and the microstructure of deposits were analyzed by SEM and XRD, respectively. The results indicated that the optimum parameters were current density 3-4 A/dm2, pH 2-3, temperature 40-50?C, cobalt sulphate 20 g/l and saccharin 2-3 g/l. Chemical analysis of the deposits by EDS revealed anomalous Ni-Co codeposition occured in this system. The SEM showed that hydroxide particles were not present on the surface and that fine-grain, smooth and compact Ni-Co alloy deposits were obtained. The crystallographic structures of Ni-Co alloy foils were the fcc Ni solid solution. The Ni-Co alloy foils with Co content 17.3-37.2 wt% and thickness of 20-45 μm were bright with low residual stress and super toughness.
基金Sponsored by National Science Foundation for Distinguished Young Scholars of China(50225415)
文摘An alternative to conventional process for the preparation of soft magnetic metal foils of Fe,Fe-Ni,Fe-Co and Fe-Ni-Co by electroforming was described.The microstructure and magnetic properties were observed.The results showed that the crystal size of the iron-based alloy foil is less than 10μm,while that of nickel-based alloy foil is about 2μm.Moreover,the electroformed Fe-Ni foil has better magnetic properties than the conventional milled permalloy 1J79 foil.
基金the National Natural Science Foundation of China(51401005)Beijing Municipal Commission of Education(KM201410005014)RiXin Talents Plan of Beijing University of Technology(2015-RX-L11).
文摘The microstructure evolution of the melt-spun Mg–7Y–4Gd–5Zn–0.4Zr alloy during annealing treatment has been investigated by using X-ray diffraction(XRD),optical microscope(OM),differential scanning calorimetry(DSC)and transmission electron microscope(TEM).The results indicated that two kinds of primary grains were contained in the melt-spun alloy.One was the supersaturated magnesium matrix,and the other was the 18R-LPSO phase.The 18R-LPSO phase transformed into the 14H-LPSO phase during annealing treatment at 300 ℃ for 0.5 h.The new precipitate of the 14H-LPSO phase was found at 300 ℃ for 5 h.Lots of linear precipitates formed as well as some precipitate with quadrangular morphology in matrix at 500 ℃ for 0.5 h.The melt-spun alloy displayed the highest hardness of 103 NHV after annealing treatment at 300 ℃ for 5 h.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 50071060) the National Specific Foundation for Excellent Ph.D. Thesis.
文摘Microstructure and subsequent phase transformations on heating of the melt-spun Nd85Al15 alloy have been studied by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The melt-spun Nd85Al15 alloy shows two-stage transformation processes as follows: amorphous+72 nm supersaturated bcc-Nd(AI) solid solution-7 nm omega-like phase-AINd3+hexagonal Nd. The activation energies for the first and second transformation were found to be 100 kj/mol and 188 kj/mol, respectively. The formation mechanism of nanoscale omega-like phase is discussed.
基金Project(51074117)supported by the National Natural Science Foundation of ChinaProject(2009CDA044)supported by the Foundation for Distinguished Young Scientists of Hubei Province,ChinaProjects(201104493,20100471161)supported by the China Postdoctoral Science Foundation
文摘Scanning electron microscopy and X-ray energy dispersive spectrum analysis show that the clusters of intermetallic AlFeSi particle are distributed on or near the aluminum foil stock surfaces heterogeneously. 3D finite element modeling shows that these clusters of hard particles induce the fracture of the nano-scale lubricant oil film at first and further lead to severe deformation in the nearby aluminum foil substrate along the rolling direction. Consequently, the optical property in this region differs from that in the surroundings, resulting in surface defects.
文摘The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10^-4s^-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are： T = 1273-1323K, p = 20-30MPa, t = 45-60min.
文摘The effects of Co as a substituent for Ni on microstructure and electrochemical capacity of hydrogen storage alloys MI（NiCoMnAl）5.4 at -30- ＋80 ℃, in which the content of Co was 0, 1.31%, 2.63%, 3.94%, 5.25%, and 6.56% （mass fraction）, respectively, were reported. All of the alloys were prepared by vacuum induction melting followed by melt-spinning. It is found that the electrochemical capacity of alloys at different temperature depends upon the compositions and preparation methods. The electrochemical capacity of alloys increases at higher temperature （40 - 80 ℃ ） and decreases at lower temperature （ - 30 - 0 ℃ ） with an increasing cobalt content. With an increasing temperature, melt-spinning is more favorable for improved capacity of the alloys than casting. Analyses of the charging/discharging potential curves illustrate that higher cobalt content and melt-spinning techniques are more effective to increase the capacity at higher temperature because of the higher hydrogen evolution potential. On the contrary, the capacity of alloys at lower temperature can be increased by decreasing cobalt content and casting, which is ascribed to higher hydrogen evolution potential and delayed hydrogen evolution reaction, as well as reduced potential drop in the charging/discharging process. XRD patterns confirm that all of the specimens present a single hexagonal CaCu5-type structure and an increased lattice parameters with increasing Co content. The FWHM of the main peak of melt-spun ribbons reduces because of more homogeneous composition and less lattice strain defects.
基金The financial supports of the Charles University Grant Agency Project(No.704119)Project TRIO FV(No.20337)of the Czech Ministry of Industry and Trade are highly acknowledged.
文摘AA8079 is a commonly used stock material for manufacturing thin packaging foils.The primary alloying elements Fe and Si can form binary and tertiary intermetallics.In-situ TEM simulating homogenization annealing process of the as-cast material was used to analyze the real-time changes of the shape,type,and distribution of these particles.They affect the mechanical properties of the final product and susceptibility of the material to the formation of pinholes and other macroscopic defects.Another set of as-cast samples were annealed in a regime simulating industrial treatment in combination with measurements of resistivity to validate the results of the in-situ experiment.The results show clear temperature intervals of recovery,matrix desaturation,and phase transformations occurring in several stages:spheroidization of the original particles above 450℃,nucleation of new particles at 475℃,particles coarsening above 525℃,and an entire dissolution of the original particles above 550℃.
文摘Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin Fe Co-V foils were studied. Detailed data about the boundaries, coincidence site lattice（CSL） relationships, grain sizes, and microstructural features were acquired from electron-backscatter diffraction（EBSD） maps. Moreover, the evolution of the magnetic properties during high-energy-beam welding was studied using vibrating sample magnetometry（VSM）. The fraction of low-angle boundaries was observed to increase in the fusion zones of both electron- and laser-beam-welded foils. The results showed that the fractions of low-Σ CSL boundaries（particularly twin boundaries, Σ3） in the fusion zones of the welded foils are higher than those in the base metal. Because the strain rates produced during high-energy-beam welding are very high（because of the extremely high cooling rate）, grain deformation by a slip mechanism is limited; therefore, deformation by grain twinning is dominant. VSM analysis showed that the magnetic properties of the welded foils, i.e., their remanence, coercive force, and energy product, changed significantly. The formation of large grains with preferred orientation parallel to the easy axis of magnetization was the main reason for the diminished magnetic properties.
