Confined pulsed current sintering behavior of molten-salt synthesized Ti3AlC2 and Ti3SiC2: Kinetic analysis and mechanical properties

Dense Ti 3 AlC 2 and Ti 3 SiC 2 ceramics were fabricated via confined pulsed current sintering using their respective powders synthesized by molten salt method. The densification kinetics, microstructural evolution, and mechanical properties were systematically investigated. Results indicated that Ti 3 AlC 2 exhibited lower thermal stability, being susceptible to decomposition and Al exudation, whereas Ti 3 SiC 2 remained highly stable. Densification was primarily governed by diffusion creep and grain boundary sliding, yielding apparent activation energies of 148 and 200 kJ·mol 1 for Ti 3 AlC 2 and Ti 3 SiC 2 , respectively. Subsequent grain growth was controlled by mixed grain boundary and lattice diffusion, with respective activation energies of 52–63 and 124–139 kJ·mol 1 . These significantly higher activation energies in Ti 3 SiC 2 fundamentally reflected its rigid Ti-Si covalent-like bonds compared to the weaker Ti-Al metallic bonds. Dictated by this intrinsic bonding difference, the Ti 3 SiC 2 ceramics achieved a higher maximum flexural strength of 740 MPa and predominantly failed via intergranular fracture, whereas Ti 3 AlC 2 reached 573 MPa and primarily exhibited transgranular cleavage.