Substitution behavior of Si atoms in the Ti2AlC ceramics

Abstract

The substitution of Si atoms in the Ti2AlC ceramics has been observed in the Ti2AlC brazing joints using AlSi eutectic filler alloy, contributing to the formation of Ti2(Al, Si)C solid solution in the interaction area according to the SEM analysis. Afterwards, a detailed characterization was performed using FIB/TEM technique. A remarkable decrease in the lattice constants has been observed in the modified Ti2AlC ceramics, and the presence of Si element in the corresponding area has been further proved by STEM. The formation and decomposition mechanisms of the Ti2(Al, Si)C solid solution have been studied via ab initio calculations. The results suggest that all the Ti2(Al1-x, Six)C structures with different Si contents are stable in the vibration aspect. However, due to the lower Gibbs energy of the competing phases, the structures with high Si content would decompose. Finally, the bulk Ti2(Al0.9, Si0.1)C has been successfully synthesized using SPS method.