Stability of ferritic MA/ODS alloys at high temperatures

The ultrafine scale microstructure of three MA/ODS ferritic alloys (12YWT, 14YWT and MA957) have been characterized by atom probe tomography in the as-received condition and after isothermal heat treatments at temperatures of up to 24 h at 1300 °C (∼85% Tm). Atom probe tomography revealed the presence of a high number density of 2-4 nm diameter titanium-, yttrium- and oxygen-enriched particles. These ultrafine particles were found to be extremely resistant to coarsening during isothermal aging at 1300 °C. Solute segregation of the alloying elements to dislocations and grain boundaries was also observed.