Anisotropy of Grain Growth in Alumina

Abstract

Grain growth in theoretically dense undoped and MgO‐doped polycrystalline Al 2 O 3 was studied, and average grain‐boundary migration rates were compared with those of a ‐plane and c ‐plane sapphire during migration into the same undoped and MgO‐doped materials. The results are discussed in terms of a grain‐size‐dependent grain‐boundary mobility‐grain‐boundary energy product, M b γ b . The grainsize dependencies of the M b γ b products for seed and matrix grains differ. Seed orientation appears to affect the nature of solute‐boundary interactions. The importance of grain‐boundary structure on migration characteristics is also indicated by a demonstration of twin‐formation‐enhanced grain growth.