Modeling of transformation toughening in brittle composites
- Los Alamos National Lab., NM (United States)
Transformation toughening by partially stabilized zirconia (PSZ) or tetragonal zirconia particles (TZP) has been used to increase the fracture toughness of brittle ceramics and intermetallics such as Al[sub 2]O[sub 3], Y[sub 2]O[sub 3], MoSi[sub 2] since the discovery of the transformation toughening of ZrO[sub 2] by Garvie et al in 1975. Continuum and thermodynamic approaches to understanding the transformation toughening phenomena have been successful in predicting the qualitative trend of the volume fraction, f, and transformation strain dependence, but quantitative agreement and the effects of the microstructure are not well described. The authors present here the modeling results of transformation toughening of brittle composites using a discrete micro-mechanical model (DMM). In the model, the material is represented by a two-dimensional triangular array of nodes connected by elastic springs. Microstructural effects are included by varying the spring parameters for the bulk, grain boundaries, and transforming particles. Using the decrease of the local stress around the crack to monitor the change of the fracture toughness, [Delta]K, they find that there is a linear dependence of toughness on the volume fraction of the transforming particles. They also find that composites with smaller transformation stresses and smaller particles are tougher than the composites with larger transformation stresses and larger particles. They have demonstrated that the discrete micromechanical model can serve as a quantitative basis for future rational design of brittle composite materials.
- OSTI ID:
- 6397278
- Journal Information:
- Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 28:11; ISSN SCRMEX; ISSN 0956-716X
- Country of Publication:
- United States
- Language:
- English
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Modeling of transformation toughening in brittle materials
Modeling of transformation toughening in brittle materials