Synergistic effects of TiCp on microstructure refinement and mechanical enhancement in Al-Si-Cu-Ni-Mg alloys

In this study, an Al-10Si-3.5Cu-2.5Ni-0.3Mg alloy with trace additions of Zr and unique micro-nano TiC particles (referred to as TiCp) was fabricated using electromagnetic stirring technology. The analysis focused on the evolution of eutectic silicon, revealing that TiCp played a significant role in modifying the eutectic Si. By inhibiting the growth of Si on twin plane re-entrant edge (TPRE) and promoting heterogeneous nucleation of Si crystals, TiCp transformed the morphology of Si from flaky to fibrous. Moreover, the alloy containing 0.3 %TiCp showed the presence of acicular (Al,Si)3Ti phase. Quantitative analyses by KAM values of EBSD showed a high stress concentration at the interface between the (Al,Si)3Ti phase and the Al matrix. Under tensile deformation, increased dislocation density at this interface led to local stress concentration and premature cracking, ultimately causing fracture of the alloy. The alloy with a trace addition of 0.1 %TiCp exhibited an ultimate tensile strength of 349 MPa, yield strength of 299 MPa, and total elongation of ,1.16 %, representing an improvement in UTS by 60-100 MPa compared to the same Al-Si-Cu-Ni-Mg alloy type. This research offers a promising approach for designing and manufacturing high-strength and ductile Al-Si-Cu-Ni-Mg alloys.