The Analysis and Modeling of Phase Stability and Multiphase Designs in High Temperature Refractory Metal-Silicon-Boron Alloys
Abstract
In order to satisfy the challenging materials requirements for operation in a high temperature (T greater than 1400 degrees C) environment, multiphase alloy microstructures in the Mo-Si-B system involving the Mo5SiB2 (T2) intermetallic phase have been identified that offer high melting temperature, oxidation resistance and attractive high temperature mechanical properties. With the T2 phase as the focal point of the microstructure designs, the fundamental basis of the alloying behavior in T2 has been established in terms of the governing geometric and electronic factors. For non-stoichiometric compositions, it has been determined that constitutional defects such as vacancies for Mo-rich compositions and anti-site defects for Mo-lean compositions control the homogeneity range. Moreover, the aggregation of constitutional vacancies has been discovered to play a key role in the development of dislocation and precipitation reactions in the T2 phase that directly impact high temperature structural performance. To establish the essential database for computational modeling, an experimental campaign has been pursued in the current work to measure high temperature solubility up to 1950 degrees C, to quantify sluggish diffusion and to characterize the defect structure in the T2 phase.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2006
- Accession Number
- ADA442984
Entities
People
- John H. Perepezko
Organizations
- University of Wisconsin–Madison