Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Elastic Constants of Mullite Containing Alumina Platelets



H M. Ledbetter, Sudook A. Kim, Martin Dunn, Z Xu, S Crudele, W Kriven


Using dynamic methods, we measured the elastic constants of a composite comprising alumina platelets (0.2 volume fraction) in a 3:2-mullite matrix. Instead of the expected elastic stiffening, we found an elastic softening. For example, the Young modulus was 222 GPa, below mullite's value of 228 GPa, and far below the value predicted by a solid-mechanics model assuming good alumina-mullite interfaces: 256 GPa. As possible softening sources, we considered voids, cracks, poor particle-matrix-interface bonding, and an enveloping third phase, either around the platelets or around the mullite particles. We concluded that the mullite particles must be enveloped by silica, an elastically soft phase. Solid-mechanics modeling considering a three-phase composite supports our conjecture. Our conjecture received further confirmation from careful SEM, STEM observations.
Journal of the European Ceramic Society
No. 14


alumina platelets, composite, elastic constants, internal friction, mullite


Ledbetter, H. , Kim, S. , Dunn, M. , Xu, Z. , Crudele, S. and Kriven, W. (2001), Elastic Constants of Mullite Containing Alumina Platelets, Journal of the European Ceramic Society, [online], (Accessed May 24, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created July 1, 2001, Updated February 17, 2017