Study On Composite Interface Control Of 1070A/7075 Aluminum Alloy By Solid-liquid Cast-rolling

Metal laminated composites can achieve the goal of combining group element metals with each other at macroscopic and microscopic levels in order to achieve complementary advantages between materials.It can make up for the shortage of a single metal material in practical application,improve the comprehensive performance of the material,and realize the wide application of the material.In this thesis,1070A/7075 aluminum alloy composite plates were prepared by solid-liquid cast-rolling composite method.By adjusting the casting temperature,casting rolling speed,subsequent composite plate annealing temperature,annealing time and other parameters of the metal clad 1070 A aluminum alloy,the influence of process parameters and annealing heat treatment on the evolution of composite interface microstructure and element diffusion of the solid-liquid cast-rolling1070A/7075 aluminum alloy composite plates was systematically studied,the coordination relationship between process parameters,microstructure and mechanical properties is clarified.The main conclusions are as follows:(1)At the same casting and rolling speed,the shear strength and elemental diffusion width increased with the increase of casting temperature;at the same casting temperature,the shear strength and elemental diffusion width increased and then decreased with the increase of casting and rolling speed;under the same process conditions,the diffusion distance of each element was Mg > Zn > Cu.When the casting temperature was 690 ℃ and the casting and rolling speed was 12m/min,the ratio of casting zone to casting and rolling zone was moderate,which realized the good metallurgical bonding of the composite plate.The shear strength,tensile strength,yield strength and elongation are 86.2 MPa,173.9 MPa,108.6 MPa and 24.9 % respectively.(2)The main reason for the increase in the strength of the composite plate is the expansion of the bonding mass at the composite plate interface along the bonding interface normal and lateral extension.The annealing heat treatment promoted the diffusion of elements in the composite 1070A/7075 aluminium alloy sheet,resulting in the formation of intermediate diffusion layers of different widths at the composite interface region,with the annealing temperature having a greater influence on the width of the transition layer.When the composite sheet was annealed at 400 °C for 2 h,the interfacial bond strength reached its maximum value of 124.4 MPa,which was 43.5 %higher than the shear strength of the composite sheet before annealing.(3)After annealing the composite sheet of 1070A/7075 aluminium alloy at 350 °C for 1 h,the width of the transition zone of the composite sheet was 3 μm and no intermetallic compounds were generated at the composite interface.The tensile properties of the composite plates are excellent,and the tensile strength,yield strength and elongation are 159.5 MPa,89.7 MPa and 26.4% respectively.(4)The hardness of the 1070 A aluminium alloy cladding region,the interfacial bonding region and the 7075 aluminium alloy substrate region of the 1070A/7075 aluminium alloy composite sheet after annealing heat treatment is mainly influenced by the second phase particles of the composite sheet,with the annealing temperature increasing,the hardness of the 7075 aluminium alloy substrate region gradually increases.