TEM characterization of structure and composition of nanosized ODS particles in reduced activation ferritic–martensitic steels

TEM investigations of different ODS steels were performed to gather information about the structure and composition of ODS particles. The structure of the nanometer-sized Y2O3 particles analysed by HRTEM shows a strong correlation of its crystallographic orientation with the alloy lattice. The orientation correlations [1 1 0]YO∥[1 1 1]FeCr and (1 1̄ 1)YO∥(1̄ 0 1)FeCr were found. HRTEM and energy-filtered transmission electron microscopy (EFTEM) investigations also show the formation of Y2Ti2O7 ODS particles due to the addition of metallic Ti in the powder before MA. Argon gas used as inert gas during the mechanical alloying was detected and tiny Ar gas bubbles trapped at the surface of ODS particles were imaged in the steel by using EFTEM.