Cu/Al clad strips are prepared using solid?liquid cast-rolling bonding(SLCRB)technique with a d160mm×150mm twin-roll experimental caster.The extent of interfacial reactions,composition of the reaction products,an...Cu/Al clad strips are prepared using solid?liquid cast-rolling bonding(SLCRB)technique with a d160mm×150mm twin-roll experimental caster.The extent of interfacial reactions,composition of the reaction products,and their micro-morphology evolution in the SLCRB process are investigated with scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD).In the casting pool,initial aluminized coating is first generated on the copper strip surface,with the diffusion layer mainly consisting ofα(Al)+CuAl2and growing at high temperatures,with the maximum thickness of10μm.After sequent rolling below the kiss point,the diffusion layer is broken by severe elongation,which leads to an additional crack bond process with a fresh interface of virgin base metal.The average thickness is reduced from10to5μm.The reaction products,CuAl2,CuAl,and Cu9Al4,are dispersed along the rolling direction.Peeling and bending test results indicate that the fracture occurs in the aluminum substrate,and the morphology is a dimple pattern.No crack or separation is found at the bonding interface after90°-180°bending.The presented method provides an economical way to fabricate Cu/Al clad strip directly.展开更多
Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the...Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the asymmetric heat transfer characteristics of Cu/Al clad strips fabricated by UDTRC.The effects of roller velocity ratio,Cu strip thickness,and inclination angle on the kissing point position,as well as the entire temperature distribution are obtained.The heat transfer model is established,and the mechanism is discussed.The Cu strip and rollers are found to be the main causes of asymmetric heat transfer,indicating that the roller velocity ratio changes the liquid zone proportion in the molten pool.The Cu strip thickness determines the heat absorption capacity and the variations in thermal resistance between the molten Al and the big roller.The inclination angle of the small roller changes the cooling time of big roller to molten Al.Moreover,the microstructure of Al cladding under different roller velocity ratios is examined.The results show significant grain refinement caused by the shear strain along the thickness direction of Al cladding and the intense heat transfer at the moment of contact between the metal Al cladding and Cu strip.展开更多
The mechanical properties and product thickness specifications of bimetallic clad strip prepared by twin-roll casting are tightly related to the mechanical behavior of bonding interface interaction.The thermal−flow co...The mechanical properties and product thickness specifications of bimetallic clad strip prepared by twin-roll casting are tightly related to the mechanical behavior of bonding interface interaction.The thermal−flow coupled simulation and the interface pressure calculation models are established with the cast-rolling velocity as the variable.The results show that the interface temperature decreases,the interface pressure and the proportion of the thickness of the Al side increase with the decrease in cast-rolling velocity.The thinning of Cu strip mainly occurs in the backward slip zone.The higher pressure and longer solid/semi-solid contact time make the interface bonded fully,which provides favorable conditions for atomic diffusion.The inter-diffusion zone with a width of 4.9μm is attained at a cast-rolling velocity of 2.4 m/min,and the Cu side surface is nearly completely covered by aluminum.Therefore,the ductile fracture occurs on the Al side,which prevents the propagation of interface delamination cracks effectively.Meanwhile,shear effect becomes more significant at high interfacial pressure and large plastic strain,and the microstructure on Al side is composed of slender columnar crystals.Thus,the metallurgical bonding and refinement of grains on the Al side can result in higher bonding strength and tensile properties of the clad strip.展开更多
The characteristics of novel Nd-Fe （Ni, Co, Al ）-B microstructure prepared by strip casting technique were studied. The novel microstructure was observed using scanning electron microscope （SEM） and transmission e...The characteristics of novel Nd-Fe （Ni, Co, Al ）-B microstructure prepared by strip casting technique were studied. The novel microstructure was observed using scanning electron microscope （SEM） and transmission electron microscope （TEM）. Along the direction of heat flow, there are two kinds of different microstructures. Close to the wheel side, there is a thick layer containing many polygonal Nd2Fe14B grains. Near the free surface side, however, there are relative uniform platelike Nd2Fe14B grains whose growth direction is not completely the direction of the heat flow during solidification. The formation of the novel microstructure is presumed to be the contribution of the special temperature field and Ni component.展开更多
To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, ...To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, with birth and death element method, a thermo-mechanical coupled finite element model(FEM) was set up to explore the temperature and contact pressure distribution at the Cu/Al bonding interface in the SLCRB process. Taking these macro-scale simulation results as boundary conditions, we simulated the atom diffusion law of the bonding interface by molecular dynamics(MD) in micro-scale. The results indicate that the temperature in Cu/Al bonding interface deceases from 700 to 320 ℃ from the entrance to the exit of caster, and the peak of contact pressure reaches up to 140 MPa. The interfacial diffusion thickness depends on temperature and rolling reduction, higher temperature results in larger thickness, and the rolling reduction below kiss point leads to significant elongation deformation of cladding strip which yields more newborn interface with fresh metal and make the diffusion layer thinner. The surface roughness of Cu strip was found to be benefit to atoms diffusion in the Cu/Al bonding interface. Meanwhile, combined with the SEM-EDS observation on the microstructure and composition in the bonding interface of the experimental samples acquired from the castrolling bite, it is revealed that the rolling reduction and severe elongation deformation in the solid-solid contact zone below kiss point guarantee the satisfactory metallurgical bonding with thin and smooth diffusion layer. The bonding mechanisms of reactive diffusion, mechanical interlocking and crack bonding are proved to coexist in the SLCRB process.展开更多
In spite of its small area, Palestine (27,000 km2) is home to more than 500 species of ornithofauna, inhabiting all types of terrestrial and aquatic habitats. The Gaza Strip (365 km2), which represents 1.5% of Palesti...In spite of its small area, Palestine (27,000 km2) is home to more than 500 species of ornithofauna, inhabiting all types of terrestrial and aquatic habitats. The Gaza Strip (365 km2), which represents 1.5% of Palestine, has a considerable number of ornithofaunistic species as well. Al-Mawasi ecosystem (14 m2), which lies in the far south-west of the Gaza Strip, has never been orinthologically studied. Thus, the current study comes to survey the ornithofauna prevailing at Al-Mawasi ecosystem as a natural to semi-natural environment. Ornithofauna were monitored using direct observations and binoculars for the lasted ten years (2009-2018). A total number of 135 ornithofaunistic species, belonging to 45 families and 17 orders were encountered at Al-Mawasi ecosystem. Passeriformes was the largest order and comprised 57 (42.2%) of the recorded species, while the non-passerines constituted the remaining 78 species (57.8%). Muscicapidae was the largest among the recorded families;represented by 13 species (9.6%), and followed by 10 species of Scolopacidae, (7.4%), 8 species of Ardeidae and Fringillidae (5.9%) for each and 7 species of Accipitridae (5.0%). Aquatic ornithofaunistic species represented 44 (32.6%) of the total species recorded, while the terrestrial ones represented 91 (67.4%). The Palestine Sunbird (Nectarinia osea) is a common endemic Palestinian species in Al-Mawasi ecosystem. The Goldfinch (Carduelis carduelis) has become an actual source of financial income for its catchers, and as a result, it is extensively hunted in vast areas of the Gaza Strip. Finally, the study recommends carrying out more research on ornithofauna inhabiting the natural, agricultural and urban environments of the Gaza Strip. The establishment of a specialized center dealing with bird surveys and conservation is very essential in the Gaza Strip, which is an actual hot spot experiencing an escalating environmental degradation.展开更多
To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current ...To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.展开更多
Aluminum ion battery(AIB)technology is an exciting alternative for post-lithium energy storage.AIBs based on ionic liquids have enabled advances in both cathode material development and fundamental understanding on me...Aluminum ion battery(AIB)technology is an exciting alternative for post-lithium energy storage.AIBs based on ionic liquids have enabled advances in both cathode material development and fundamental understanding on mechanisms.Recently,unlocking chemistry in rechargeable aqueous aluminum ion battery(AAIB)provides impressive prospects in terms of kinetics,cost,safety considerations,and ease of operation.To review the progress on AAIB,we discuss the critical issues on aluminum electrochemistry in aqueous system,cathode material design to overcome the drawbacks by multivalent aluminum ions,and challenges on electrolyte design,aluminum stripping/plating,solid-electrolyte interface(SEI)formation,and design of cathode materials.This review aims to stimulate exploration of high-performance AAIB and rationalize feasibility grounded on underlying reaction mechanisms.展开更多
基金Project(51474189)supported by the National Natural Science Foundation of ChinaProject(QN2015214)supported by the Educational Commission of Hebei Province,China
文摘Cu/Al clad strips are prepared using solid?liquid cast-rolling bonding(SLCRB)technique with a d160mm×150mm twin-roll experimental caster.The extent of interfacial reactions,composition of the reaction products,and their micro-morphology evolution in the SLCRB process are investigated with scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD).In the casting pool,initial aluminized coating is first generated on the copper strip surface,with the diffusion layer mainly consisting ofα(Al)+CuAl2and growing at high temperatures,with the maximum thickness of10μm.After sequent rolling below the kiss point,the diffusion layer is broken by severe elongation,which leads to an additional crack bond process with a fresh interface of virgin base metal.The average thickness is reduced from10to5μm.The reaction products,CuAl2,CuAl,and Cu9Al4,are dispersed along the rolling direction.Peeling and bending test results indicate that the fracture occurs in the aluminum substrate,and the morphology is a dimple pattern.No crack or separation is found at the bonding interface after90°-180°bending.The presented method provides an economical way to fabricate Cu/Al clad strip directly.
基金Project(51974278)supported by the National Natural Science Foundation of ChinaProject(E2018203446)supported by the Natural Science Foundation of Hebei Province Distinguished Young Fund Project,ChinaProject(2018YFA0707303)supported by the National Key Research and Development Project of China。
文摘Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the asymmetric heat transfer characteristics of Cu/Al clad strips fabricated by UDTRC.The effects of roller velocity ratio,Cu strip thickness,and inclination angle on the kissing point position,as well as the entire temperature distribution are obtained.The heat transfer model is established,and the mechanism is discussed.The Cu strip and rollers are found to be the main causes of asymmetric heat transfer,indicating that the roller velocity ratio changes the liquid zone proportion in the molten pool.The Cu strip thickness determines the heat absorption capacity and the variations in thermal resistance between the molten Al and the big roller.The inclination angle of the small roller changes the cooling time of big roller to molten Al.Moreover,the microstructure of Al cladding under different roller velocity ratios is examined.The results show significant grain refinement caused by the shear strain along the thickness direction of Al cladding and the intense heat transfer at the moment of contact between the metal Al cladding and Cu strip.
基金the financial support from the National Natural Science Foundation of China(No.51974278)the Natural Science Foundation of Hebei Province Distinguished Young Fund Project,China(No.E2018203446)the National Foundation of Key Research and Development Project of China(No.2018YFA0707303)
文摘The mechanical properties and product thickness specifications of bimetallic clad strip prepared by twin-roll casting are tightly related to the mechanical behavior of bonding interface interaction.The thermal−flow coupled simulation and the interface pressure calculation models are established with the cast-rolling velocity as the variable.The results show that the interface temperature decreases,the interface pressure and the proportion of the thickness of the Al side increase with the decrease in cast-rolling velocity.The thinning of Cu strip mainly occurs in the backward slip zone.The higher pressure and longer solid/semi-solid contact time make the interface bonded fully,which provides favorable conditions for atomic diffusion.The inter-diffusion zone with a width of 4.9μm is attained at a cast-rolling velocity of 2.4 m/min,and the Cu side surface is nearly completely covered by aluminum.Therefore,the ductile fracture occurs on the Al side,which prevents the propagation of interface delamination cracks effectively.Meanwhile,shear effect becomes more significant at high interfacial pressure and large plastic strain,and the microstructure on Al side is composed of slender columnar crystals.Thus,the metallurgical bonding and refinement of grains on the Al side can result in higher bonding strength and tensile properties of the clad strip.
文摘The characteristics of novel Nd-Fe （Ni, Co, Al ）-B microstructure prepared by strip casting technique were studied. The novel microstructure was observed using scanning electron microscope （SEM） and transmission electron microscope （TEM）. Along the direction of heat flow, there are two kinds of different microstructures. Close to the wheel side, there is a thick layer containing many polygonal Nd2Fe14B grains. Near the free surface side, however, there are relative uniform platelike Nd2Fe14B grains whose growth direction is not completely the direction of the heat flow during solidification. The formation of the novel microstructure is presumed to be the contribution of the special temperature field and Ni component.
基金Funded by the General Program of National Natural Science Foundation of China(Nos.51474189 and 51674222)the Excellent Youth Foundation of Hebei Scientific Committee,China(No.E2018203446)the Scientific Research Foundation of the Higher Education Institutions of Hebei Province,China(No.QN2015214)
文摘To explore the complex thermal-mechanical-chemical behavior in the solid-liquid cast-roll bonding(SLCRB) of Cu/Al cladding strip, numerical simulations were conducted from both macro and micro scales. In macro-scale, with birth and death element method, a thermo-mechanical coupled finite element model(FEM) was set up to explore the temperature and contact pressure distribution at the Cu/Al bonding interface in the SLCRB process. Taking these macro-scale simulation results as boundary conditions, we simulated the atom diffusion law of the bonding interface by molecular dynamics(MD) in micro-scale. The results indicate that the temperature in Cu/Al bonding interface deceases from 700 to 320 ℃ from the entrance to the exit of caster, and the peak of contact pressure reaches up to 140 MPa. The interfacial diffusion thickness depends on temperature and rolling reduction, higher temperature results in larger thickness, and the rolling reduction below kiss point leads to significant elongation deformation of cladding strip which yields more newborn interface with fresh metal and make the diffusion layer thinner. The surface roughness of Cu strip was found to be benefit to atoms diffusion in the Cu/Al bonding interface. Meanwhile, combined with the SEM-EDS observation on the microstructure and composition in the bonding interface of the experimental samples acquired from the castrolling bite, it is revealed that the rolling reduction and severe elongation deformation in the solid-solid contact zone below kiss point guarantee the satisfactory metallurgical bonding with thin and smooth diffusion layer. The bonding mechanisms of reactive diffusion, mechanical interlocking and crack bonding are proved to coexist in the SLCRB process.
文摘In spite of its small area, Palestine (27,000 km2) is home to more than 500 species of ornithofauna, inhabiting all types of terrestrial and aquatic habitats. The Gaza Strip (365 km2), which represents 1.5% of Palestine, has a considerable number of ornithofaunistic species as well. Al-Mawasi ecosystem (14 m2), which lies in the far south-west of the Gaza Strip, has never been orinthologically studied. Thus, the current study comes to survey the ornithofauna prevailing at Al-Mawasi ecosystem as a natural to semi-natural environment. Ornithofauna were monitored using direct observations and binoculars for the lasted ten years (2009-2018). A total number of 135 ornithofaunistic species, belonging to 45 families and 17 orders were encountered at Al-Mawasi ecosystem. Passeriformes was the largest order and comprised 57 (42.2%) of the recorded species, while the non-passerines constituted the remaining 78 species (57.8%). Muscicapidae was the largest among the recorded families;represented by 13 species (9.6%), and followed by 10 species of Scolopacidae, (7.4%), 8 species of Ardeidae and Fringillidae (5.9%) for each and 7 species of Accipitridae (5.0%). Aquatic ornithofaunistic species represented 44 (32.6%) of the total species recorded, while the terrestrial ones represented 91 (67.4%). The Palestine Sunbird (Nectarinia osea) is a common endemic Palestinian species in Al-Mawasi ecosystem. The Goldfinch (Carduelis carduelis) has become an actual source of financial income for its catchers, and as a result, it is extensively hunted in vast areas of the Gaza Strip. Finally, the study recommends carrying out more research on ornithofauna inhabiting the natural, agricultural and urban environments of the Gaza Strip. The establishment of a specialized center dealing with bird surveys and conservation is very essential in the Gaza Strip, which is an actual hot spot experiencing an escalating environmental degradation.
基金supported by the National Natural Science Foundation of China(Nos.51974196,52275361,and 52105390)Open Research Fund from National Key Laboratory of Metal Forming Technology and Heavy Equipment(S2308100.W01)+1 种基金Natural Science Foundation of Shanxi Province(No.20210302124426)Special Funds for the Central Government to Guide Local Science and Technology Development(No.YDZX20191400002149).
文摘To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.
基金the National Research Foundation of Singapore(NRF)Investigatorship Award Number NRFI2017-08/NRF2016NRF-NRFI001-22.
文摘Aluminum ion battery(AIB)technology is an exciting alternative for post-lithium energy storage.AIBs based on ionic liquids have enabled advances in both cathode material development and fundamental understanding on mechanisms.Recently,unlocking chemistry in rechargeable aqueous aluminum ion battery(AAIB)provides impressive prospects in terms of kinetics,cost,safety considerations,and ease of operation.To review the progress on AAIB,we discuss the critical issues on aluminum electrochemistry in aqueous system,cathode material design to overcome the drawbacks by multivalent aluminum ions,and challenges on electrolyte design,aluminum stripping/plating,solid-electrolyte interface(SEI)formation,and design of cathode materials.This review aims to stimulate exploration of high-performance AAIB and rationalize feasibility grounded on underlying reaction mechanisms.
