J. Mat. Proc. Tech. Vol. 117/3 Special CD ROM Edition

THERMEC 2000 - Proceedings of the International Conference on Processing and Manufacturing of Advanced

Materials. Edited by T. Chandra, K. Higashi, C. Suryanarayana, and C. Tome. Elsevier Science, Las Vegas, NV, 2001

-

Processing and Fracture Response of Morphologically Textured Alumina

Peyton W. Hall and Desiderio Kovar

Texas Materials Institute and Department of Mechanical Engineering,

University of Texas at Austin, Austin, TX 78712, USA

Abstract

Fracture toughness of ceramics can be improved by introducing microstructural features that enhance frictional grain bridging. One method that has been suggested for accomplishing this is by processing ceramics with an aligned, elongated grain structure (morphological texture) so that the number of grain bridges can be increased. To test this hypothesis, highly textured alumina has been fabricated, characterized, and tested. X-ray analysis reveals that these materials exhibit a strong fiber texture. Image analysis has been performed that shows a direct correlation between the observed crystallographic and morphological textures. Fracture toughness measurements performed using fracture mechanics specimens reveal that, despite an increase in the number of bridging grains, fracture toughness is not strongly affected by texture. Implications for designing ceramics with significantly improved fracture toughness and reliability are discussed.

Keywords: ceramic; alumina; texture; fracture toughness; morphology; grain bridging