Gd. Zhan et al., Effect of annealing conditions on microstructural development and phase transformation in silicon carbide, J AM CERAM, 83(6), 2000, pp. 1369-1374
The effect of annealing with and without applied pressure on the microstruc
tural development and phase transformation was investigated in fine-grained
beta-SiC ceramics containing alpha-SiC seeds. Materials annealed without p
ressure had a microstructure consisting of elongated grains, while material
s annealed with pressure showed a duplex microstructure consisting of small
matrix grains and some of elongated grains. However, annealing with pressu
re (25 MPa) was found to greatly retard phase transformation from beta -->
alpha polytypes and inhibit grain growth. This change in lattice parameter
suggests that the retardation of phase transformation and grain growth migh
t be attributed to a reduced mass transport rate, which is the result of Al
being introduced into the SiC by the annealing pressure.