Phase Stability and Microstructural Design in High Temperature (Mo,Nb)-Si-B Alloys
Abstract
The challenges of a high-temperature (T> 1400 deg C) environment impose severe constraints on materials selection in terms of melting temperature, oxidation resistance and structural functionality. In order to satisfy these criteria refractory metal silicides that can develop adherent SiO2 oxidation layers emerge as the most attractive candidates However, multiphase microstructure designs must be applied to address the toughening and strengthening issue that must be resolved for the use of refractory metal silicides. In the current work, a stable two-phase equilibrium between Mo and a Mo5SiB2 intermetallic (T2) phase has been established. While this stability is an attractive attribute, it is also a challenge in developing processing strategies that will allow for the manipulation of microstructure in order to achieve designs that will offer enhanced performance at high temperature. New microstructure control based solidification processing (including rapid solidification) has been demonstrated. An in situ precipitation reaction to yield Mo dispersions within the Mo5SiB2 intermetallic phase has been discovered and found to be effective in enhancing strength and toughness.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 15, 1999
- Accession Number
- ADA369845
Entities
People
- John H. Perepezko
Organizations
- University of Wisconsin–Madison