Interfacial diffusion and microstructural evolution in cast-rolled C18150Cu/8011Al composites: A molecular dynamics study

Cu/Al laminated composites are valued for their excellent combination of electrical and thermal conductivity, mechanical strength, and lightweight. However, diffusion mechanisms in multi-component industrial alloys produced by the cast-rolled method remain unclear. This study developed a solid-liquid multi-component interface model based on industrial-grade C18150Cu (containing Cr and Zr) and 8011Al (containing Fe and Si). A hybrid EAM/Tersoff potential function was employed to model isothermal diffusion at 983 K and non-equilibrium solidification at 0.1 K/ps. The results revealed significant asymmetry in the diffusion kinetics among constituent elements. The diffusion coefficient of Al (25.3 nm 2 /ns) was two orders of magnitude larger than that of Zr (0.1 nm 2 /ns) and exceeds those of the other constituents. Activation energies for diffusion in Al, Fe, and Si were low (13.8, 19.7, and 24.2 kJ/mol, respectively), while Zr exhibited a substantially higher value (194.85 kJ/mol), indicating a pronounced interfacial pinning effect. During non-equilibrium solidification, significant nucleation initiated at 850 K, while the precipitation of IMCs occurred at 533 K in the residual liquid. It was observed that Si atoms exhibit pronounced interfacial segregation during late cooling. The resulting interfacial configuration consisted of a gradient with an Al 2 Cu layer (∼51 Å), an Al 4 Cu 9 layer (∼16 Å), and a solid solution layer. The total thickness of the diffusion layer measured 163.3±2.5 Å, which was 8%–11% less than that recorded in the pure Cu/Al system. This study provides a theoretical foundation for understanding interfacial composition and improving the cast-rolled technique for Cu/Al laminated composites.