(1.State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China) （2. Key Laboratory of Nonferrous Metal Alloys of Ministry of Education, Lanzhou University of Technology, Lanzhou 730050,China)
A356/6082 composite plate was fabricated by liquid-solid rolling composite technique and subsequent T6 heat treatment.Microstructure changes of composite plate, interfacial element diffusion, mechanical properties of the shear strength and micro-hardness before and after T6 heat treatment were researched by optical microscopy (OM), scanning electron microscope (SEM), microhardness measurements and shear tests. The results showed that the morphology of eutectic silicon in the A356 aluminum alloy changes from long, coarse platelike to fine spherical after T6 heat treatment. The eutectic silicon agglomeration near the interface disappeared and the microstructure is more homogeneous. Near the interface, the Mg elements obviously diffuse. In addition, the shear strength of composite plate increases from 91.6 to 139.2 MPa, and the micro-hardness near the interface and the substrate both increases significantly. The average hardness value of the A356 side reaches about 1102.5 MPa and the average hardness value of the 6082 side reaches about 851.6 MPa. Micro-hardness value of the A356 side to the 6082 side decreases gradually along the vertical interface.