Synthesis mechanism and interface contribution towards the strengthening effect of in-situ Ti5Si3 reinforced Al matrix composites

As a titanium-silicon intermetallic compound, Ti₅Si₃ can offer great potentials as a reinforcement agent in metal matrix composites due to its exceptional mechanical and physical properties. In this study, Ti₅Si₃ particles are successfully in-situ synthesized in Al-Si-Ti system through the interdiffusion reaction between Ti-Si using a powder metallurgy approach. The composites interface structure is transformed from Al/Ti₅Si₃ non-coherent interface to Al/TiSi/Ti₅Si₃ coherent/semi-coherent interface with the formation of TiSi transition layer. It enhances the interface bonding between Ti₅Si₃ particles and Al matrix, mitigates the mechanical differences between the matrix and the reinforcements, thereby enhancing the coordinated deformation ability. Simultaneously, the generated gradient interface between Ti@Ti₅Si₃ core-shell structure particles and Al matrix suppresses the rapid propagation of cracks in brittle reinforcement. As a result, the mechanical performance of AMCs is improved to 96.1 GPa for elastic modulus and 327 MPa for strength while maintaining a fracture elongation of 6.5 %, which shows significantly enhancement compared with Al-5Si and Al-2.37Ti matrix. These findings establish a robust microstructural foundation for fully harnessing the strengthening effects of the reinforcements and provide a feasible technical route of utilizing the in-situ synthesized reinforcing particles for improving the mechanical performance of Al matrix composites.