BETA-]ALPHA-TRANSFORMATION IN POLYCRYSTALLINE SIC-II, INTERFACIAL ENERGETICS

The β→α transformation in polycrystalline Sic occurs by the rapid growth of composite grains consisting of α‐SiC plates “sandwiched” between grains of recrystallizedp‐SiC. Growth of these composite grains into the fine‐grained β matrix occurs much more rapidly than thickening of the α plates into their β“envelopes.” A phenomenological analysis of the energetics of these several growth processes is presented and it is shown that the observations can be explained by the extreme anisotropy of the interfacial energy between β− and α−SiC; {lll}β(0001)α interfaces have much lower energies than random, β/α interfaces. In reaction‐sintered Sic, this anisotropy is manifested by rapid growth of a seeds along their basal planes into the epitaxial β reaction product; slow growth occurs perpendicular to the basal planes. Copyright © 1978, Wiley Blackwell. All rights reserved