Synergistic effect of in-situ TiC particles synthesis on microstructure and mechanical properties of Fe-rich eutectic Al-Si alloy

The presence of long acicular Fe-rich intermetallic compound phases in recycled Al-Si alloys significantly affects the mechanical properties of the alloy. In-situ formed ceramic particles, serving as reinforcing phases, can optimize the material's performance while maintaining thermodynamic stability. This study utilized the in-situ preparation method via a stir casting process to produce TiC/Al-Si-Fe composite materials, investigating the impact of in-situ TiC particles on the mechanical properties and microstructural evolution of the Al-12Si-1.7Fe cast alloy. The potential for TiC formation was assessed based on the principles of chemical reaction thermodynamics. The results indicate that the addition of Ti and C refined the microstructure and led to a more uniform phase distribution. Some Fe-rich phases transformed from long acicular structures to fishbone-like structures, effectively alleviating stress concentration. Furthermore, the formation of a small amount of AlTi phase, in conjunction with the hard TiC reinforcing particles, significantly reduced the average coefficient of friction from 0.91 to 0.6, shifting the wear mode from a complex pattern to one dominated by abrasive wear. However, the presence of incompletely reacted carbon particles and the segregated (Al,Si)Ti phase negatively impacted the susceptibility to brittle failure of the matrix. This in-situ ceramic particle preparation method provides valuable guidance for the study of wear resistance, phase transformation, and strengthening mechanisms in recycled Fe-rich Al-Si alloys.