Fig. 1. TKD IPF maps and pole figures from (a) the plain view and (b) a cross-section of the CrCoNi alloy. (c) A high-resolution TEM image of a typical columnar grain. TBs and stacking faults are marked with red and green dash lines, respectively. (d) A typical electron diffraction pattern obtained from a plan-view sample. (e) STEM-EDXS results of the area shown at the left. (f) A plan-view TEM image (upper) and the corresponding EDXS line scan results (lower) along the yellow line.

Fig. 2. (a) Engineering stress-strain curve from in-situ compression along a direction perpendicular to the film growth direction. The red curve was from the sample to be analysed in detail below. Numbers 1-4 indicate 4 deformation stages: before compression, right after yielding, a middle stage of deformation, and a late stage of deformation. Inset is a schematic illustration of the substrate, the columnar structure and loading configuration. (b) Engineering stress-strain curve from in-situ compression along the film growth direction. The red curve is the representative curve for detailed analysis below. Inset is a schematic illustration of the substrate and columnar structure and loading configuration. (c) Comparison of yield strengths of other FCC alloys. CG represents coarse-grained.

Fig. 3. (a) The representative pillar at stages 1, 3 and 4. (b) The microstructure of a pillar at stage 2 from another pillar. The green box indicates part of the shear band area. (c) A magnified image of the area marked by the white square in (b).

Fig. 4. (a) The microstructure at stage 4. The green rectangle indicates the boundary of the shear band area. (b) and (c) Magnified images of the areas indicated with the white and yellow rectangles, respectively, in (a).

Fig. 5. (a) The microstructure of typical columnar grains before compression. (b) The microstructure of a deformed columnar grain after yielding. The yellow dash lines pointed by arrows indicate twin planes. (c) The microstructure of a columnar grain at a late deformation stage. (d) An enlarged image of the area marked with the red rectangle in (c). The red dash lines mark twin boundaries.

Fig. 6. Typical plan-view TEM images of nc CrCoNi films at (a) the as-deposited state and after annealing for 2 h at: (b) 873 K and (c) 1073 K. Grains showing clear nanotwins or stacking faults were marked with red circles. (d) Grain size and hardness at various annealing temperatures. (e) Measured grain size vs annealing temperature curves for the nc CrCoNi in this study and other nc metallic materials from the literature. The annealing durations of these other materials were ≤ 2 h. MD simulations of the thermal stability of (f) nc Ni and (g) nc CrCoNi at 1000 K.

Fig. 7. (a) Cross-sectional microstructure of a pillar compressed along the grain growth direction immediately after the yield point. Yellow arrows point to some intact columnar grains. Collapsed grains are shown below the yellow dash line. (b) A magnified image of the red rectangle area in (a).