In situ reactive synthesis and phase stability investigation in the AlN-SiC system

Solid solutions in the AlN-SiC system were synthesized via the in-situ reactive synthesis using Si₃N₄, Al and C as the starting materials. The reactant mixtures with ratios of Si₃N₄:Al: C =1:4:3 were fired for 1 to 3h at temperatures ranging from 1600°C to 1900°C in a nitrogen atmosphere. The effects of different firing temperature and soaking time on phase and microstructural characteristics of the final product were studied by XRD and HRTEM/EDS. The results showed that the product synthesized at 1900°C was a single-phase AlN-SiC solid solution with the wurtzite (2H) crystal structure. As soaking time increased, the AlN-SiC solid solution decomposed into modulated structures, which indicated that a miscibility region exists in the system of AlN-SiC.