Long-term stability of 14YT-4Sc alloy at high temperature

14YT alloy (Fe-14Cr-0.25wt%Y2O3-0.4wt%Ti) with 4 at% Sc addition was previously reported to exhibit a nanoscale microstructure and high strength when annealed at temperatures up to 1000 °C (0.65Tm) for 1 h. Here we report that the microstructure and mechanical behavior of 14YT-4Sc alloy after long-term annealing for up to 60 h at 1000 °C. FIB analysis shows abnormal grain growth with annealing time, while a large fraction of the matrix still consists of nanoscale grains. TEM images reveal a slight growth of nano grains, with estimated grain growth exponent, n, to be 0.29. Sc-Ti-Y-O enriched nano oxide particles (<10 nm) were observed in EDS mapping of the 14YT-4Sc-60h sample. The nano-structure retention at the high temperature of 1000 °C for 60 h is attributed to these complex nano oxides.