Oxide distribution in PBF-LB/M-processed ODS steel: Effects of ball milling and dielectrophoretic deposition in powder production

This study provides key insights into the critical role of nanoparticle distribution in oxide dispersion-strengthened (ODS) powders for laser powder bed fusion (PBF-LB/M). A comparative analysis of mechanical (ball milling, BM) and liquid-based (dielectrophoretic deposition, DD) additivation methods was conducted to produce ODS feedstocks by integrating 1 vol.-% yttria (Y 2 O 3 ) nanoparticles into Fe20Cr metal powder. ODS materials enhance high-temperature strength and creep resistance by dispersing fine, stable oxide particles within a metal matrix. This makes the precise size and distribution of nanoparticles crucial in the final bulk material. Powder characterisation shows that while both methods produce powders suitable for high-density parts, the DD method achieves higher uniform nanoparticle distribution, with smaller average particle sizes (74 nm) and interparticle distances (826 nm). In contrast, longer milling durations resulted in slightly larger particle sizes (77 nm) and distances (790 nm), while shorter milling times produced even larger nanoparticles (108 nm) with greater interparticle distances (1114 nm). These results suggest that DD offers advantages in optimising the distribution of oxide nanoparticles to enhance the strengthening effects in high-temperature applications.