Diffusion behaviors and electric conductivity of 7072/7075/7072 heterostructure sheet during heat treatment

To illustrate the relationship between diffusion behavior of atoms (Cu, Mg, Zn) and heat solution process, and their effects on the electrical conductivity and properties of 7075 composite, the effect of heat solution temperature and soaking time on 7072/7075/7072 composite sheets were explored by microstructure analysis property test. Results indicate the diffusion distance of Cu, Mg, and Zn atoms at the interface increases linearly with increased holding time, with Cu atoms showing slower diffusion rates than Mg and Zn. Electrical conductivity decreases exponentially with increased holding time, stabilizing after 50 min, consistent with result of atoms diffusion. From a distance of 85–155 μm from the surface, the Vickers hardness linearly increases from the 7072 cladding layer to the 7075 core, stabilizing beyond the distance of 200 μm. Tensile properties of the 7075 composite sheet at room temperature increase with increased soaking times, and reach peaking between 2 and 15 min of soaking, alongside an increase in elongation.