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.