Controlled Ceramic-Ceramic Eutectic Microstructures
Abstract
Preparation, microstructure, crystallography and mechanical properties of high melting oxide eutectics are described. It is shown that the microstructure can be predicted from the volume fraction of the minor phase. Two basic criteria control the interface and crystallographic orientation: (i) minimization of the misfit between oxygen sublattices (ii) neutralization of ionic charge across the interfacial plane. The fracture strength is related to the colony size and decreases only slightly from room temperature to 1600 C. The fracture surface energy does not exhibit any dependence on fiber spacing. Knoop microhardness is greater than that of either the magnesia or spinel separately. The creep resistance of the grain microstructure is greater than that of the colony microstructure and MgAl2O4 single crystal. A void nucleation and growth mechanism may best describe the deformation process with eutectic ingots containing colonies or grains.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 18, 1976
- Accession Number
- ADA034235
Entities
People
- R. C. Bradt
- V. S. Stubican
Organizations
- Pennsylvania State University