Strength-ductility synergy and multiscale particle-solute interaction mechanisms in Al-Cu composites reinforced by TiC/TiB2 nanoparticles

• TiC/TiB 2 refines Al composite grains 92.7%. • The maximum volume of Al 2 Cu is refined by 96.7% • Diffusion-blocking model shows particle–dendrite interactions. • Heat-flow-solute and phase-field model reveals segregation behavior. This work proposes a novel manufacture method to enhance t1%he strength–ductility synergy of Al–Cu alloys by incorporating TiC/TiB 2 particles. The composites were fabricated using an in-situ synthesized Al-30TiC/TiB 2 master alloy, followed by ultrasonic-assisted casting and T8 heat treatment. A multiscale modeling approach combining ProCAST and Cellular Automata was established to simulate dendritic growth, solute distribution, and particle–matrix interactions. The results indicate that the introduction of TiC/TiB 2 suppresses macro-segregation of Cu, promotes heterogeneous nucleation, and refines the microstructure. Compared with Al Cu alloy, the grain size was reduced by 92.7% in the as-cast state. The tensile strength increased by 14.6%, reaching 543 MPa, while the elongation increased from 8.4% to 9.4%. A dendrite growth model was established based on the diffusion blocking effect of nanoparticles. Quantitative analysis revealed that TiC/TiB 2 particles inhibited dendritic growth, reducing the growth rate from 14.2 mm/s to 7.3 mm/s. Strengthening mechanism analysis confirms that Orowan strengthening is dominant (60.2%), followed by thermal mismatch (33.6%) and grain refinement (6.2%). This work significantly enhances the strength–ductility synergy of Al–Cu alloys by incorporating TiC/TiB 2 micro–nano particles, while establishing a multiscale simulation framework to systematically elucidate the interaction mechanisms between particles and solute transport behavior.