Grain Boundary Structure in Alumina

Grain boundary microstructures in alumina ceramics are prone to show glassy phases, faceting, and some fraction of highly coincident twin-related boundaries. These separate phenomena and their inter- actions have been studied in six distinct materials of both commer- cial and experimental origin. Glass containing materials show high density of (SIGMA) = 3 basal twins and few others. Some hot pressed materials show, in addition to basal twins, (SIGMA) = 7 rhombohedral twins and two distinct varieties of 10(')11 twins new to alumina. All these boundaries are analyzed using the CSL/DSCL model and an idealized axial ratio c/a = SQRT.(15/2); 0 lattice methods are employed to estimate the error introduced by that idealization. The basal and rhombohedral twins seem well-described by the model, while the 10(')11 ones show unexpected displacements from coincident geometries.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Metallurgical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Shiue, Yeong Ruey

• Engineering, Materials Science

Identifier

(UMI)AAI8600313

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71825