Fig. 1. (a) and (b) SEM images of the typical Fe-Al pillar; (c) illustration of the high temperature pillar compression test; (d) variation in hardness for the single-phase FeAl and FeAl2 phases; (e) and (f) typical compressive stress-strain curves for the layered FeAl/FeAl2 pillars tested from 150 to 500 °C; (g) evolution of the critical resolved shear stress along (101) plane of FeAl layer.

Fig. 2. (a) and (b) Typical SEM images of the micro-pillar before and after compression at 200 °C; (c) compression induced extrusion of the FeAl layer and slip steps in the FeAl2 phase; (d) and (e) TEM images displaying the defect structures after compression.

Fig. 3. (a) and (b) Typical SEM images showing the pillar before and after compression at 450 °C; (c) TEM image of a thin-foil cut from the deformed pillar; (d) and (e) TEM micrographs showing the defect structures in the pillar after compression.

Fig. 4. (a) and (b) Typical SEM images of the pillar before and after compression at 500 °C. Although the layers in the micro-pillar have a high inclination angle with respect to the loading axis, the FeAl layers are free to deform, as marked by arrows. (c) Highlight of the surface deformation features. (d) SEM image of the thin-foils cut from deformed pillar. The yellow arrows mark the unconstrained layers. (e)-(g) TEM images showing defect structures in the compressed pillar.