Fabrication,Microstructures And Mechanical Properties Of Al/Mg/Al Composite Sheets With Three-Dimensional Layer Interface

In this study,Al/Mg/Al composite sheets with trapezoidal layer interface,wavelike layer interface and triangular layer interface were prepared by multi-pass hot rolling process.The evolution behavior of three-dimensional(3D)layer interface during rolling was studied,and the effects of 3D layer interface with different shapes on the microstructure and mechanical properties of the composite sheets were analyzed.The influence mechanism of 3D layer interface on crack propagation behavior of composite sheets was elucidated.The stress field and temperature field of the composite sheet were simulated by finite element simulation software(Deform)during the rolling process,revealing the stress distribution state at the interface of the composite sheets with 3D layer interface of different shapes.The results demonstrated that the interface of the composite sheets achieved the strong interface metallurgy bonding,without visible voids,cracks,and other defects.The introduction of the 3D interface layer significantly improved the interface bond strength of the composite sheets.The interface layer composed of Al₃Mg₂ and Al₁₂Mg₁₇ was observed at the interface of the composite sheets.The thickness of the intermetallic compounds(IMCs)layer varied with the position of the interface,and the IMCs layer was the thinnest near the center of the sheets.The IMCs layer was continuously coarsening and fragmenting with the increase of rolling deformation.The stress concentration was easily generated at the interface between the Mg layer and the Al layer,so the crystal grains near the IMCs layer were more refined than that inside of the component sheets,which made the experimental strength of the composite sheets higher than the predicted strength.With the increase of rolling deformation,the internal grain size gradually increased,and the IMCs layer was fragmented,which decreased the tensile properties of the composite sheets.The interface layer with moderate thickness and intact interface in the composite sheets appeared uniformly broken when they were under tensile stress,and the direction of microcracks generated was perpendicular to the tensile direction,which hindered the crack propagation and delayed the fracture of the composite materials and thereby enhanced the elongation of the composite sheets.Simultaneously,that the 3D layer interface made the cracks deflect along the interface was conducive to the strengthening and toughening of the interface area and improved the plasticity of the composite sheets.The introduction of 3D layer interface changed the stress distribution state at the interface of the composite sheets.Since the rolling compressive stress was decomposed along the interface into the rolling compressive stress perpendicular to the interface and the rolling shear stress parallel to the interface at the inclined interface,the trapezoidal layer interface and the wavelike layer interface increased the rolling compressive stress of the composite sheets,and the triangular layer interface reduced the rolling compressive stress of the composite sheets,which affected the texture of the composite sheets,and then affected the composite sheets mechanics properties.Deform simulation results showed that the interface transition of the wavelike layer interface composite sheet is smooth,which was beneficial to alleviate stress concentration,and its comprehensive mechanical properties were also optimal.