Compressive Strength and Indentation Damage in Ceramic Materials.
Abstract
The extent of the plastically deformed region associated with indentation in silicon carbide is determined by means of selected area electron channeling. It is found that the extent of the plastic zone beneath an indent is quite large, i.e., equal to about five times the impression radius. Microcrack formation is studied in the SEM, and the combined results are discussed in terms of current elastic-plastic indentation fracture models. The first cracks to form are radial microcracks; their morphology, and the observed indentation plastic zone dimensions, support the elastic-plastic model of Perrott for indentation cracking in alpha-SiC. In addition, scanning electron microscopy and acoustic emission have been used to characterize the microfracture mechanisms responsible for the temperature-sensitive compressive strength behavior of polycrystalline Al2O3 and alpha-SiC. It is determined that the early stages of damage can be related to the presence or absence of microplasticity, depending upon the ceramic. Further, local plastic flow in alpha-SiC is clearly observed to commence during compression at temperatures as low as 500 C, and at stresses not much greater than the tensile strength.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 31, 1978
- Accession Number
- ADA057790
Entities
People
- David L. Davidson
- James Lankford Jr.
Organizations
- Southwest Research Institute