Fabrication And Properties Of Ti-Cu And Cu-Cu Laminated Composites By Ultrasonic Consolidation

In recent years,with the development of technology,the role of metal laminated structures is becoming increasingly important.Ti/Cu laminated structures not only have the advantages of light weight,corrosion resistance,but also have the advantages of good conductivity,ductility and so on.Ultrasonic consolidation(UC)is a rapid method for preparing metal laminated structures with high energy saving,low temperature and low production cost.The intelligent manufacture and integrated consolidation can be realized by combining ultrasonic and computer numerical control(CNC)milling process.It has broad application prospects in the fields of aerospace,industrial production and national defense equipment.Using the new UC machine developed in HEU,this thesis dealt with the Cu/Cu laminated structures,Ti/Cu laminated structures,which were made of TAI?T2 and Al 8011 foils.The effects of processing parameters on the microstructure,properties of Cu/Cu and Ti/Al laminated structures were systemically studied using metallographic microscope,scanning electron microscope,X-ray diffractometer,INSTRON universal testing machine and Electrochemical workstation.Their characterization of interface bonding strength by peeling.Finally,the mechanism of ultrasonic consolidation was discussed and analyzed to illustrate the effect of the addition of interlayer(Al 8011).The results obtained by Orthogonal experiment indicated that the optimal parameters to fabricate Cu/Cu laminated structures with superior performance are:normal force 1715N,vibration amplitude 33?m,welding speed 20mm/s,temperature 170?.After peeling test,the two categories of failure mode of Cu/Cu laminated structures were observed,the two failure modes are clear break with high response of peel load and failing at breaking point grew under loading.Observation of the interface defects,there are three kinds of interface defects:point defect,line defect and irregular shape defect.The interface line welding density(LWD)was calculated,the result indicated that there is no positive correlation between the LWD and the peeling load.The results obtained by Response surface methodology(RSM)indicated that the optimal parameters to fabricate Ti/Cu laminated structures with superior performance are:normal force 1715N,vibration amplitude 40?m,welding speed 10 mm/s,temperature 170?.After peeling test,the failure mode of Ti/Cu laminated structures was complete peeling phenomenon.The model equation obtained by RSM as follow:Y=-1793.67+2.15 x1-29.54 x2 +28.74x3+8.67×10-3xx1x2-1.52×10-3x3-0.41x2x3-6.09×10-4x12+0.41x22-0.48x32(x1—normal force,x2—vibration amplitude,x3—welding speed).The results are consistent with the actual results.After the analysis of the significance and the interaction of two factors,the effect of vibration amplitude on the ultrasonic consolidation is the first,the welding speed is second,the normal force is third,but the three are indispensable.Further high vibration amplitude reduced LWD and caused the interface material clusters to form defects,material surface appeared cracks;future increase in normal force was found to result in considerable decrease in LWD and the thickness of middle layer;Welding speed determines amount of energy input per unit length and per unit time.Very low welding speed is undesirable for a number of reasons.Very low welding speeds could roughen the foil surface,reduced LWD and resulted in unacceptable levels of strain hardening or fatigue-related effects at the interface leading to poverty deterioration.Ultrasonic energy can provide conditions for significant diffusion.The width of the diffusion zone was 2-3 ?m,and there was no new phase formation,considering the resolution limit of the EDS and XRD technique.With high tensile strength,the fracture direction was in a certain angle,the crack extended to the interior of the material.Due to strain hardening and solid solution strengthening,the fracture was cleavage and plastic mixed fracture morphology.The interface of the material was superior with the inner layer and the interlayer occurred bend at the same time.The materials with different thickness have different corrosion resistance and electrical conductivity.The conductivity of the Ti/Cu laminated structures improves with increasing ratio of Cu,the corrosion resistance of the materials improves with increasing ratio of Ti.Aluminum foil can provide a good plastic deformation "bridge" for Ti and Cu to overcome the difficulty of two kinds of materials in poor plastic,and the wettability of aluminum and copper is excellent,so as to realize the combination of two kinds of materials at low temperature.