Solidification Behavior and Microstructural Evolution of In-Situ Fabricated Al-12.5wt%Si-(TiB2 + Al2O3) Hybrid Composite

This study focuses on investigating the solidification behavior of Al-12wt%Si-10%(Al2O3 + TiB2) metal matrix composite fabricated through an in-situ stir casting technique. The hybrid composite was prepared using salt-metal reactions, and real-time thermodynamic data was recorded using a DAQ system to obtain the cooling curve. Microstructural characterization, DSC, and cooling curve investigation were performed. The microstructural examination confirmed the successful fabrication of the composite. Latent heat of fusion, ΔHf, and crystallization, ΔHc were calculated as 408.84 J/gm and 271.73 J/gm respectively, which further confirms the faceted growth of silicon with non-faceted growth of aluminum using the modified Jackson and Hunt theory. Various characteristic temperatures, including nucleation, growth, and recalescence, were determined from the cooling curve as 659.51 °C, 580.26 °C, and 14.84 °C, respectively. The cooling rate was calculated as 108.93 °C/s, and the solidification rate as 26.82 °C/s. The cooling rate affected the growth of both eutectics. The in-situ formed reinforcements acted as grain refiners for the aluminum–silicon alloy, resulting in the heterogeneous nucleation of α-Al.