Update on the Status of Ods Alloys for Fossil Energy Applications

The goal of this project is to generate data that demonstrate and quantify earlier improvements in joining, microstructural modifications to minimize isotropy effects, and environmental lifetime modeling, in terms that can be readily assessed by potential users of oxide dispersion-strengthened (ODS) alloys. A report has been prepared compiling results from the literature of ODS alloy joining trials to provide a comprehensive documentation of the methods, procedures, and resulting microstructures and mechanical properties of joining methods available for use with ODS alloys. This report will be updated as continuing evaluations of joining techniques are completed and the results reported. Some further results from joining using pulsed plasma-assisted diffusion bonding, and transient liquid phase bonding are reported here. Long-term environmental exposures of representative ODS FeCrAl alloys in air have been completed, and data required for refinement of an oxidation-limited life-prediction model developed earlier are being generated from post-test analyses. Continuing exposures in a CO2-steam mixture (at 1100°C in 500h cycles, with 1h at temperature each cycle and cooling to room temperature) have exceeded 3kh, and results so far indicate a greater degree of scale spallation than observed in air (in 100 h cycles), starting at 1 to 2kh for ODS alloys MA956 and PM2000, whereas much less scale spallation was observed for a non-ODS (weaker) model FeCrAlY alloy.