Microstructurally Developed Toughening Mechanisms in Ceramics -- Stress-Induced Martensitic Reactions. I. Theory of Metastable Phase Retention and Contribution to Fracture Toughness.
Abstract
Prevention of a martensitic reaction is explained by relating the internal pressure, which arises through matrix constraint, to pressure-temperature-compositional phase equilibria. To have a constraint, microcracking must be avoided by fabricating the material with a grain/particle size less than a critical value. This is a previous result of theories concerned with crack extension in highly localized stress fields. The contribution of a stress-induced martensitic reaction to fracture toughness is explained in terms of the work done by the crack's stress field to overcome the matrix constraint. This analysis shows that the important factors contributing to the fracture toughness are the structural shape change, the elastic properties of the constraining materials, the volume fraction of the retained metastable phase, and the radius of the transformed zone at the crack front. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1978
- Accession Number
- ADA057239
Entities
People
- F. F. Lange