Nanostructure of Oxide Dispersion-Strengthened Steel Mechanically Alloyed with Intermetallic Fe3Y

In this work, the nanostructure of oxide dispersion-strengthened steel 13.5Cr–Fe3Y ODS, obtained by mechanical alloying of oxidized matrix steel powder and Fe3Y intermetallic powder. In addition to the initial state, the effect of thermal aging on the nanostructure of this steel at 650°C for 500 and 1000 h was investigated. In the studied states of 13.5Cr–Fe3Y ODS steel, transmission electron microscopy (TEM) has detected nanoscale oxides (~10–12 nm) with a number density of ~4–7 × 1021 m–3, pores (~3.0–3.6 nm and ~2–4 × 1022 m–3), as well as the dislocations ~2 × 1014 m–2. According to the energy-dispersive X-ray spectroscopy analysis, oxide particles are mainly enriched in Y and O, and the detected pores contain up to 3 at. % Ar. Atom probe tomography (APT) revealed the presence of clusters (~3–5 nm and ~8–30 × 1022 m–3). The detected clusters also contain Ar within 0.1 at. %. Comparison of the data on the initial state and states after thermal aging revealed an increase in the number density of oxides and a decrease in their size with an increase in the thermal aging time, while the volume of the oxide phase at 1000 h remains the same relative to the initial state within the limits of error. Comparison of APT data showed an increase in the volume of clusters during aging up to 500 h and a decrease in the volume at 1000 h. An increase in the number of oxides during thermal aging up to 1000 h correlates with a decrease in the volume of clusters in the same state. There is a significant (~2 times) decrease in pore volume during thermal aging. The density of dislocations increases to ~5 × 1014 m–2 when reaching 1000 h of aging.