Understanding Impacts of Chemistry on Oxidation of FeCrAl Alloys in Multiple Environments

Traditionally, FeCrAl alloys have played an important role in high temperature applications due to their ability to form a passive Al oxide film at temperatures above ~800C. Recently, however, FeCrAl alloys have become of interest for the application of accident tolerant nuclear fuel cladding. Because lower temperature applications are less studied with FeCrAl materials, in this presentation we show significant work being done by GE to better understand how Al, Cr, and Mo all play a role on both oxidation kinetics and thermodynamics. Several model and commercial prototype alloys have been tested in hydrothermal corrosion autoclave loops, low temperature steam exposure (~400C), high temperature steam exposure (~1000C or higher), and high temperature air exposures. In this study we show that both Cr and Al play a signficant role in both high temperature and low temperature oxidation of FeCrAl, and that the role of Mo is much less signficant. Additionally, the use of machine learning has helped to gain further insight on both predicting future optimized chemistries as well as balancing the properties of hydrothermal corrosion, low and high temperature steam oxidation, and thermal aging (which is excacerbated due to radiation in a nuclear reactor environment). GE plans to use this framework to further optimize the FeCrAl alloy system for use in nuclear reactor environments.