PSI - Issue 80

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

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Fig. 3 The microstructure of investigated alloys (a) EBSD map of Sanicro25. (b) EBSD map of FeAlOY. (c) Detail showing bimodal grain distribution in FeAlOY. (d) STEM micrograph of fine grains.

3.2. Cyclic hardening/softening behavior

Fig. 4(a) shows the cyclic hardening/softening curves of Sanicro 25, and Fig. 4(b) shows those of FeAlOY, obtained under different total mechanical strain amplitudes. The evolution of stress amplitude with the number of cycles indicates that Sanicro 25 exhibits softening behavior across all four strain amplitudes. FeAlOY also shows gradual softening, which becomes more pronounced at higher total strain amplitudes. Fig. 4(c-d) present the corresponding development of plastic strain amplitude as a function of cycle number. For Sanicro 25, the plastic strain amplitude shows a slight increase which corresponds to softening shown in Fig. 4(a). In contrast, FeAlOY displays consistently low plastic strain amplitudes, indicating higher stiffness of the material. A sudden increase in plastic strain amplitude is observed at the highest total strain amplitude, which corresponds well with the enhanced softening seen in Fig. 4(b). This behavior can be associated with annihilation of dislocations inside the finer grains and also with the formation of PSBs as mentioned in (Chan, 2023)