Research of Microstructurally Developed Toughening Mechanisms in Ceramics. Part 3. Experimental Observations in ZrO2-Y2O3 System.
Abstract
Materials in the ZrO2-Y2O3 system (less than or equal to 7.5 m/o Y2O3) were fabricated to investigate the conditions required to retain the metastable, tetragonal phase and to determine the contribution of the stress-induced martensitic reaction to fracture toughness. Retention of the tetragonal phase was optimized by minimizing porosity and maintaining the grain size below a critical valve. The critical grain size increased from 0.2 micrometers to 1 micrometer for compositions ranging between 2 m/o Y2O3 to 3 m/o Y2O3, respectively. These results are consistent with the theories developed regarding the thermodynamics of the martensitic reaction in a constrained state. In the tetragonal plus cubic phase field (compositions between 3.0 and 7.5 m/o Y2O3), the critical stress intensity factor decreased from 6.3 MPa.m1/2 to 3.0 MP.a1/2 as the volume fraction of the retained, tetragonal phase decreased to zero. Theoretical results, derived from the concept that the crack's stress field does work to unconstrain the transformation, are in good agreement with the experimental results. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1981
- Accession Number
- ADA098423
Entities
People
- F. F. Lange