Synergistic optimization in solidification microstructure and mechanical performance of novel (TiCxNy- TiB2)p/Al nanocomposites: Design, tuning and mechanism

Tuning solidification microstructure remains a grand challenge for ceramic particles reinforced Al-Si based composites due to adverse interactions between ceramic particles and Si-containing melts. This work proposed a novel in-situ synthesis strategy of designing master alloys decorated with well-dispersed TiCxNy and TiB2 particles to synergistically optimize the Al-Si based composites. By adjusting the reactant contents and ratios, near spherical nano-sized TiCxNy particles and hexagonal submicron-sized TiB2 particles were obtained in as synthesized Al-(TiCxNy -TiB2)(p) master alloys. The effects of this pre-dispersed agent on solidification kinetics, microstructure features and mechanical performance evolution of the Al-10Si-2Mg composites were investigated in detail. TiCxNy-TiB2 particles could trigger the heterogeneous nucleation of primary alpha-Al crystals, and the growth-restricting effects also contributed to grain refinement, which finally accounted for the enhancement in both strength and ductility. This work is expected to provide new guidance for selection of reinforcing particles and synergistic optimization of the solidification microstructure and performance.

Automated summary

This study proposes a novel approach to optimize the solidification microstructure of ceramic particle reinforced Al-Si based composites. By synthesizing master alloys decorated with well-dispersed TiCxNy and TiB2 particles, the composite's strength and ductility are enhanced through triggering heterogeneous nucleation and grain refinement.