PSI - Issue 80

Tomáš Vražina et al. / Procedia Structural Integrity 80 (2026) 244 – 255 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

248

5

Sanicro25 FeAlOY

0.45; 0.40; 0.32; 0.30 0.45; 0.40; 0.35; 0.32

9; 8; 6.4 ;6 9; 8; 7; 6.4

0.11; 0.13; 0.16; 0.17 0.11; 0.13; 0.14; 0.16

2.10 -3 2.10 -3

3. Results 3.1. Microstructural Characterization

The microstructure of Sanicro 25 consists of an austenitic matrix with carbides distributed along the GBs, as shown in Fig. 2(a). EDS analysis confirmed that these are complex carbides containing C, Nb, Cr, and W. In contrast, the FeAlOY microstructure features a fine dispersion of oxide- yttria (Y₂O₃) nanoparticles approximately 20 nm in size ,uniformly distributed within the matrix Fig. 2(b). Occasionally, alumina nitrides and chromium carbides are also observed similarly to (Chlupová et al., 2020) , likely resulting from processing-induced inhomogeneities and kinetics of reactions during fabrication.

Fig. 2 EDS maps showing the microstructural composition of (a) Sanicro25 (b) FeAlOY.

Grain morphology and crystallographic orientation were assessed using EBSD, as illustrated in Fig. 3(a) for Sanicro 25 and Fig. 3(b) for FeAlOY. Sanicro 25 exhibits polyhedral grains with characteristic annealing twins. An average grain size is approximately 52 ± 19 µm. In contrast, the microstructure of FeAlOY reveals irregular grains predominantly elongated along the rolling direction, with an estimated average grain size of 210 ± 58 µm. FeAlOY features a bimodal grain size distribution as evident from Fig. 3(c-d). A rather rare population of finer grains approximately 1 µm in size was also reported previously by Chlupová (Chlupová et al., 2021) for different ODS steel. Such bimodal structures originate from partial recrystallization that was recently reported to have beneficial effect on the strength and toughness of CrCoNi medium entropy alloys (Slone et al., 2024).