Research of Microstructurally Developed Toughening Mechanisms in Ceramics. Stress Induced Transformation Toughening. Part 1. Size Effects Associated with Constrained Phase Transformation Thermodynamics.
Abstract
The thermodynamics of the constrained phase transformation is presented with particular reference to size effects introduced by surface phenomena concurrent with the transformation, e.g., the formation of solid-solid surfaces (twins, etc.) and solid-vapor surfaces (e.g., microcracks). It is shown that these surface phenomena not only introduce a size-dependent energy term into the total free energy change, but also reduce the strain energy associated with the transformation, which can result in a transformation at a temperature where the chemical free energy change is less than the unrelieved strain energy associated with the constrained transformation. The results of this analysis lead to a phase diagram representation that includes the size of the transforming inclusion. This diagram can be used to define the critical inclusion size required to prevent the transformation and/or to obtain the transformation, but avoid one or more of the concurrent surface phenomena. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1980
- Accession Number
- ADA092253
Entities
People
- F. F. Lange