Formation mechanisms of Ti3(Si,Al)C2/Al2O3 composites from Ti3AlC2 and SiO via low-temperature sintering

Ti3SiC2/Al2O composites have attracted attention due to their excellent mechanical and electromagnetic properties, but the high temperatures (>= 1400.) required for the densification of aluminum oxide (Al2O3) leads to the decomposition of Ti3SiC2. To address this issue, Ti-3(SixAl(1-x))C-2/Al2O3 (x represents the Si content) composites were synthesized for the first time via hot-pressing (HP) sintering and current- assisted sintering (CAS) of mixed Ti3AlC2 and silicon monoxide (SiO) powders at 1300 and 1200., respectively. Both approaches produced composites with x values greater than 0.9, indicating that the compositions of the prepared composites were similar to those of Ti3SiC2/Al2O3 composites. The synthetic mechanism involved substitution and continuous interdiffusion of Al and Si atoms. The composite prepared by CAS at 1200. was compacted, whereas the composite prepared by HP had a low density. The low-temperature densification mechanism is attributed to the combined effects of amorphous SiO, liquid Al, and the high heating rates for CAS. The flexural strength and hardness of the composite prepared by CAS were also comparable to those of compacted Ti3SiC2/Al2O3 composites.