Fig. 1. SEM image of (a) As-received Fe-14Cr stainless steel powder, (b) Tellurium (Te) powder and (c) Y2O3 powder.

Fig. 2. (a) Schematic representation of DED process and scanning path used in the present work. (b) Macro photograph of typical ODS steel sample produced by the DED process.

Fig. 3. EBSD image quality, inverse pole figure, and KAM figures of the (a) AM-A and (b) AM-B deposition layers in the build-up direction and (c) the corresponding grain size distributions. (d) HAADF-STEM images of AM-A and AM-B deposition layers showing their coarse and relatively refined grains, respectively.

Fig. 4. (a) HAADF-STEM images showing dispersion of NPs and the NP size distribution of (a) AM-A and (b) AM-B.

Fig. 5. (a) HAADF-STEM image and the corresponding EDS element maps of the AM-A deposition layer showing coarse core-shell NPs. (b) HAADF-STEM image and element maps of typical NPs in AM-A. (c) HR TEM image obtained from the pink box area in Fig. 5(b) (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.).

Fig. 6. (a) STEM-HAADF image and corresponding EDS element maps of the AM-B deposition layer, showing the fine dispersion of NPs. (b), (c) HAADF-STEM image and element maps of typical NPs in AM-B. (d) BF image of particle in Fig. 6(c) and diffraction pattern obtained from entire BF image area.

Fig. 7. Engineering tensile stress-displacement curves of AM-A and AM-B deposition layers obtained at 22, 600, and 800°C.

Fig. 8. Engineering tensile stress-displacement curves of AM-A and AM-B deposition layers obtained at 22°C. Tensile loading axis is taken along z-axis.

Fig. 9. Nanoindentation results for (a) AM-A and (b) AM-B samples. The parenthesized numbers in blue and black show the hardness values of coarse- and fine-grain regions, respectively (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.).

Fig. 10. Schematic representation of the grain refinement mechanism of Te-added ODS steel.