Regulation of combustion behavior and microstructure of Si-alloyed porous TiAl3 intermetallics through self-exothermic reaction

In this study, Si-alloyed porous TiAl₃ intermetallic compounds were synthesized through an efficient and rapid self-exothermic reaction. The gas permeability and pore structure of the samples were quantitatively analyzed using 3D-X-ray microtomography (3D-XRM). Combined with a self-made "visual window" and real-time temperature curves, the entire green compact exhibited a distinct and uniform exothermic behavior at every moment. The addition of Si element transformed the intense solid-liquid reaction into a relatively gentle two-step sintering process. The results indicated that an appropriate amount of Si can significantly enhance the uniformity of pore structure and increase the mechanical properties by nearly five times. Meanwhile, the oxidation kinetics curves revealed that the oxidation process was divided into an initial rapid oxidation stage and a subsequent slow oxidation stage, and the mass gain ratio of the samples gradually decreased with the increase of Si content. Furthermore, a dense Al₂O₃ oxide layer can form on the surface of skeleton at high temperatures, effectively hindered the inward diffusion of oxygen and provided a feasible design concept for achieving porous TiAl₃-based composites with high porosity and excellent performance.