Study On Constitutive Model,Microstructure And Mechanical Properties Of Cu/Al Laminated Composites

For the moment,preparation processes of Cu/Al composites include connection,rolling,extrusion technology and hot pressing diffusion.Because of simple operation,low requirement to equipment,and realizing easily industrialization,Cu/Al composites has attracted wide attention of domestic and foreign scholars.In this paper,we mainly study the model,microstructure and mechanical properties of Cu/Al composite thin strip under different manufacturing technique and heat treatment.We get the stress-strain curve of Cu/Al composites about different strain rate and temperature by Gleeble3800 thermal simulation testing machine.At the same time,we analysis the microstructure,fracture morphology,peeling interface morphology and the compound composition on the interface of Cu/Al composite thin strip through the OM,SEM,EPMA,XRD,EDX and other means and getting the following conclusions:(1)We get the stress-strain curve of Cu/Al laminated composites by Gleeble3800 thermal simulation testing machine.The plane stress increases with the increasing of strain,decreasing with the rising temperature and the rule unconspicuous depend on strain rate in the process of thermal compression.There is a demarcation point in the range of strain(0.4～0.6)due to the different hardness of dissimilar materials.We have analysis the change law of plane stress and established the constitutive model of Cu/Al composite material by modifying the Fields-Backofen equation.(2)In the process of asymmetrical rolling,large shear deformation is obtained on the interface between metal matrix layers.The oxide film has broken and fresh metal extruded.The macroscopic shape of Cu/Al laminated composites has flat gradually with the increasing asymmetrical speed ratio(1.0～1.3).The thickness of the interface diffusion layer increases gradually and the peeling strength with the increasing of the asymmetrical speed ratio(1.0～1.7).There is the largest peeling strength when the asymmetrical speed ratio is 1.3.(3)The interfacial transition layer plays a buffer role in the non coordinated deformation between layers during tensile process.But the interface between the layers is destroyed because of the non synchronous deformation of the matrix.There is the best tensile properties in the tensile process after annealing at 300℃ owe to the similar extension rate of Cu and Al.(4)The thickness of the interface diffusion layer increases gradually with the increasing treatment temperature and the thickness are 1.87μ,7.42μ and 30.58μ at 300℃,400℃ and 500℃.The higher temperature and the faster growth rate.Accoirding to the XRD results,we know that the main intermetallic compound is A12Cu,AlCu and AlCu4 at 300℃ and generates Al4Cu9 at higher temperature than 400℃.There is the largest peeling sthrength at 350℃ treatment.(5)The thickness of the interface diffusion layer increases gradually with the increasing treatment time and the thickness are 6.13μ,6.77μ,13.67μ and 19.43μ at 0.5h,1h,4h and 7h.The peeling experiment shows that peeling strength of interface is maximum when the holding time is 1h.We can see that the effect of annealing temperature on the interface diffusion layer is much larger than that of the diffusion layer by the thickness of the diffusion layer.