Formation of multi-scale (TiB2+TiC)/Al layered composites via in-situ Ti2AlC synthesis and decomposition

Based on the mechanism of promoting sintering and toughening via the MAX phase Ti 2 AlC during thermal sintering, this study introduces (TiAl + TiC) for in-situ synthesis and thermal decomposition of Ti 2 AlC to generate multi-scale TiC particles. By combining freeze casting and pressure infiltration techniques, a nacre-inspired multi-scale (TiB 2 +TiC)/Al layered composite is successfully prepared. In this work, the effects of (TiAl + TiC) content on the microstructure, mechanical properties, and frictional wear properties are investigated. The results show that, with the addition of (TiAl + TiC), the bending strength , crack initiation toughness ( K I C ), crack propagation toughness ( K J C ), and wear resistance of the composites improve, while the compressive strength deteriorates. The composite with 10 vol% (TiAl + TiC) exhibits the highest bending strength (586 MPa) and best wear resistance. In contrast, the composite with 20 vol% (TiAl + TiC) demonstrates superior fracture toughness , with K I C (18.32 MPa m 1/2 ) and K J C (38.22 MPa m 1/2 ) improving by 16.2 % and 14.9 % respectively, compared to those of the composite with 0 vol% (TiAl + TiC). The developed composite material exhibits superior strength, toughness, and wear resistance compared to most structural materials. This is mainly attributed to the supporting effect provided by the micro/sub-micro-scale TiC particles generated via the in-situ synthesis and decomposition of Ti 2 AlC. All in all, these enhanced properties result from the combined effects of multiple mechanisms, including crack blunting and deflection, multi-crack propagation, as well as metal layer bridging, plastic deformation , and pull-out behavior.