Effect of atomic diffusion on interfacial heat transfer and tensile property of copper/aluminum composites

Copper/Aluminum composites (Cu/Al), combining advantages of both copper and aluminum materials, are widely used in diverse engineering fields including aerospace, electronic communication, transportation, etc. Considering multiple application scenarios of Cu/Al, it is of great significance to explore the thermal and mechanical properties and clarify the changes under various conditions. Here, the thermal property and mechanical performance in the interfacial layer of Cu/Al with different temperatures and sizes are studied using molecular dynamics (MD) simulation, and the influence of interfacial atomic diffusion is discussed. When the atomic diffusion at the interface of Cu/Al is weak under low temperature conditions (i.e., <750 K), copper and aluminum maintain Face Center Cubic (FCC) phase, and Cu atoms diffuse into Al-FCC phase. With the increase of size parameters, the equivalent phonon thermal conductivity of the interfacial layer increases and tends to be flat, while the yield strength increases first and then decreases. The equivalent phonon thermal conductivity of Cu/Al interfacial layer is positively correlated with the thickness of interfacial layer under low temperature conditions. When the temperature exceeds 750 K, severe atomic diffusion occurs at the Cu/Al interface, a large amount of Al transforms into disordered structure, and Cu atoms diffuse into the disordered Al phase. At this time, the equivalent phonon thermal conductivity of the interfacial layer decreases with the increase of temperature, which is opposite to the change trend of the interfacial layer thickness. Influenced by brittle-hard intermetallic compounds formed by atomic diffusion, the yield strength also decreases with the increase of temperature. These results shall provide guidance for the applications of Cu/Al in wide temperature ranges.