Study On Processing,Microstructure And Mechanical Properties Of Cu/Al-Si Alloy Thin Composites

Roll bonded Cu/Al laminated composite has attracted much attention over the whole world for its simple processing properties,low requirement to equipment and easy to be industrialized.This thesis focus on microstructure and mechanical properties of Cu/Al-Si alloy thin composite fabricated by symmetric and asymmetric rolling after annealing under the magnetic field,and also analyzes the same thin composite under traditional treatment with different Si content.Microstructure,fracture morphology of peeled sample and interfacial phases are analyzed with the use of OM、SEM、EPMA、XRD、EDX.There are several parameters discussed in this thesis,including different mismatch speed,magnetic field intensity and direction,annealing temperature and time under magnetic field,different Si content in Al-Si alloy,we have concluded the following ones:1)When the mismatch speed is 1.2,interface of as-rolled sample is long wave-like,and its annealing station at "400℃+9T+30min" exhibits wider values as 7.16 μm than mismatch speed of 1.1 and 1.6.2)As magnetic field intensity increases ranging from 0T to 9T,widths of interface first increase and then decrease,reaching the highest at 0.1 T with the maximum micro-hardness.It should be noted that width of interface at 1T is higher than ones at non-magnetic field.Magnetic field direction also influences diffusion of interface,and width of interface at positive station is lower than negative station.3)Width of interface increases as annealing temperature improves,this situation goes faster at temperature ranging from 350℃ to 400℃.The value of interface reaches 9.9 μm at the situation of "400℃+0.1T+30min".Growth of interface layers conforms to parabolic law with the prolonging of annealing time,three layer compounds from Al-Si alloy side to Cu side are Al2Cu、AlCu、A14Cu9,respectively.It also proved the growth rate of interface layer from fast one to the low at heat treatment station of "300～400℃+30min" is Al2Cu、Al4Cu9、AlCu.4)As Si content increases,width of interface becomes wider at the same annealing station and reaches to the maximum at 8.66%Si content.Tensile strength of Cu/Al-Si alloy increases and elongation degreases as Si content adding up.The comprehensive properties of composite are best at station of mismatch speed 1.7 and 4.84%Si content,and their tensile strength and elongation are 188.63 MPa、39.1%,respectively.And fracture morphology of composites related to base metals.Main fracture pattern of Cu is shear fracture with morphology of ridge-like,but situation of Al-Si alloy is the comprehensive characteristic of shear and ductile,there are more and more dimples in central zone of Al-Si alloy as Si content increases.5)Peeling strength of Cu/Al-Si alloy goes contrary to Si content increasing,there are there intermetallic compounds in the peeled surface with the use of SEM and XRD,which are Al2Cu、AlCu、Al4Cu9,respectively.Fracture morphology of peeled is these different compounds.As Si content goes on,micro-hardness of Al-Si alloy base metal increases,with variation of Si content from 1.82%to 8.66%,micro-hardness goes from 32.5MPa to 42.6MPa,and the value of Cu reaches the maximum at Si content 8.66%.