Fig. 1. EDS mapping and HAADF-STEM microstructure characterization of the CrCoNi-O alloy. (a) Elements distribution characterized by EDS mapping. The light domains were enriched in Ni and Co while Cr and O were concentrated in the dark domains. (b) Low magnification HAADF-STEM image of the CrCoNi-O alloy morphology. Atomic resolution HAADF-STEM images of (c) FCC matrix and (d) Cr2O3 phase, and the insets showing the corresponding fast Fourier transform (FFT) pattern. BD, beam direction. (e) HAADF-STEM image of the typical phase boundary structure at atomic scale. (f) GPA images showing the strain field maps of horizontal normal strain (εxx), vertical normal strain (εyy) and shear strain (εxy) near the phase boundary.

Fig. 2. In-situ TEM tensile tests showing the interactions between dislocations and dispersed oxides. (a) Series TEM images captured from Supplementary Video 1 showing dislocation piled up in front of oxides. (b) Screenshots from Supplementary Video 2 showing the interactions between dislocations and dispersed oxides, the orange dashed line showing the full dislocation splitting into leading and trailing Shockley partials. (c) Extended dislocation core structure in Fig. 2(b) and the full Burgers vector is determined to be 1/2[101]. (d) Post-mortem HAADF-STEM image shows that the dislocations were pinned by dispersed oxides.

Fig. 3. In-situ TEM tensile tests showing the dislocation behaviors in Cr2O3 phase and interactions between phase boundary and dislocations. (a) Series of TEM images taken during in-situ TEM straining experiments showing that the dislocations were hindered by oxide and tangled, the green dashed line indicated dislocation slip in oxide. (b) A sequence of TEM images showing the dislocation motion in Cr2O3 phase and interactions between phase boundary and dislocations. Geometrically necessary dislocations (GNDs) are marked by orange arrows. The white dashed line represents the interface between the FCC matrix and Cr2O3 phase. The red dashed boxes indicate the transport of dislocations from the FCC matrix to the Cr2O3 phase, and the insets is an enlarged view about dislocation transmission, the red arrows in the insets indicate the transported dislocation. The blue arrows indicate the slip of dislocations within the Cr2O3 phase.

Fig. 4. In-situ SEM compression tests of CrCoNi-O micro-pillars with and without Cr2O3 phase and post-mortem characterization of the deformed micropillars. (a) Engineering stress-strain curves for pillars with and without Cr2O3 phase. (b) SEM images of pillar with Cr2O3 phase before and after compression. (c) SEM images of a pillar not containing Cr2O3 phase before and after compression. (d) HAADF-STEM image of compressed micropillar containing the ceramic phase. (e) TEM dark field image taken in the region marked with red box in (d), which displays massive dislocation slip within the Cr2O3 phase. (f) HAADF-STEM image shows the details of the region in white rectangle in (d). (g) Atomic resolution HAADF-STEM image of deformation nanotwins taken in the blue box in (f). TB, twin boundary. (h) HAADF-STEM image of a compressed micropillar without a secondary phase extracted with the FIB system. (i) TEM bright field image taken in the region marked with purple box in (h) indicates that dislocation tangling did not occur while dislocation lines were observed.