Effect Of Trace Copper On Microstructure And Mechanical Properties Of 1060 Aluminum Foil For Batteries

1060 aluminum foil is often used as battery aluminum foil because of its good electrical conductivity,easy processing and forming.Its role is to carry the electrode active material,and to collect and output the current generated by the electrode active material.The 1060 aluminum foil produced by the casting and rolling method often does not meet the performance requirements of battery aluminum foil because of its low tensile strength and elongation.This article chooses to add trace copper,and improve its mechanical properties.In this paper,microstructure and mechanical properties of 1060 battery aluminum foil were systematically investigated via OM,POM,SEM,EBSD,XRD and other microstructure analysis methods,combined with micro-hardness,sheet tensile,aluminum foil tensile and other mechanical property testing methods.The influence of electrolyte corrosion resistance test,conductivity test and other analytical methods were used to verify the corrosion resistance and conductivity of 1060 battery aluminum foil.Research indicates:The addition of Cu element could refine the grains of 1060 cast billet,cold rolled billet,annealed billet and aluminum foil.The effect on the second phase particles was not significant,and it had a slight effect on the texture of the cold rolled billet: the subgrains and orientation angle were reduced,and the average size was refined from 3.8 ?m to 3.3 ?m,the average orientation angle was reduced from 7.39° to 6.24°,and the number of sub-grains in the 1?m class was doubled;the grains were refined in cold-rolled plates,and the grain boundary fluctuation characteristics was obvious,resulting in a significant reduction in the recrystallized grain size after intermediate annealing.The average grain size of the cross section was refined from 51.3?m to 30.3?m;the average grain size of the final aluminum foil with thickness of 15?m along the surface direction was refined from 3.08?m to 2.67?m.The size,morphology and composition of the second phase in the rolled billet were not changed,all were ?-(Al-Fe)phase containing only Al and Fe.After recrystallization annealing,all the ?-(Al-Fe)phases were melted to form an ?-(Al-Fe-Si)phase with Fe: Si?2;The two-phase composition and average size were basically unchanged,both were ?-(Al-Fe-Si)phase with Fe:Si?2,so the change of the second phase were not the main reason for the change in mechanical properties.The texture type in the cold-rolled billet does not changed,both were B{110}<112> and C{111}<112> textures,and both contain a small amount of Goss{100}<011> and Cube{100}<001> textures,but the Goss{100}<011> texture content increased,and the overall texture strength increased slightly;part of the texture of aluminum foil with thickness of 15?m changed from B texture to S and S1 texture,texture strength slightly increased.The above phenomenon was mainly due to the addition of Cu element,the stacking fault energy of the aluminum alloy decreased.As the stacking fault energy decreased,the dislocation cross-sliding ability decreased,thereby delaying the dislocation annihilation due to the cross-slip,and forming a variety of small angles boundaries,produce fine subgrains and smaller orientation angles;during further cold rolling,the dislocation density storage increases,and the work hardening rate increases even more,Not only manifested in small subgrains and smaller orientation angles,but also the grain characteristics of the cold-rolled sheet fluctuated,and the grain size also decreased slightly;therefore,the total area of grain boundaries increased,providing more the nucleation area,so the nucleation rate of recrystallization increased,the recrystallization rate increased,and the recrystallization temperature decreased by 25°C,which lead to the recrystallization of crystal grains,the degree of recrystallization increased,and the cubic texture content increased.The S texture content increased,the texture strength increased slightly,and the grains were refined.In addition,this paper also systematically studied the effect of Cu element on the mechanical properties,electrical conductivity and corrosion resistance of 1060 cast billet,cold rolled billet,annealed billet and aluminum foil.The results show that after adding Cu element,the tensile strength of the cast-rolled billet is basically unchanged,the yield strength is slightly increased,and the engineering strain is increased by about 9%;the tensile strength of cold-rolled billet is increased by about 10 Mpa,and the microhardness is increased by about 5HV,The shear lip and tenacity of the tensile fracture are deeper;the tensile strength of the 15 ?m thick aluminum foil in all tensile directions is increased by about 8.0%,and the engineering strain is increased by about 76.0%.The tensile fracture is transformed from brittle fracture to Ductile fracture.The tensile strength of the same 1060 aluminum foil in the RD direction is similar to that in the TD direction,and both are about 10 MPa higher than the DD direction.The differences in strength and plasticity during cold rolling,recrystallization,and foil rolling further increased,which were consistent with the evolution of its grains,subcrystals,texture,and second phase.The increased in tensile strength of aluminum foil may be due to the combination of fine grains and slightly higher texture strength of aluminum foil after adding a small amount,and the increased in elongation of aluminum foil may be due to the more uniform second phase and grain size of aluminum foil after adding a trace More subtle causes.The conductivity and corrosion resistance of 1060 aluminum foil are basically unchanged,the tensile strength were increased by about 8.0%,and the engineering strain were increased by about 76.0%.It meets the mechanical performance requirements of battery aluminum foil,and has been used in enterprise production.