Fig. 1 Backscatter electron images for a cast Al-5 at.% Cr, b cast Al-5 at.% Mo, c cast Al-5 at.% Si, d cast Al-5 at.% Ti, e nanocrystalline Al-5 at.% Cr alloys

Fig. 2 Backscatter electron images for a cast Al-5 at.% Cr, b cast Al-5 at.% Mo, c cast Al-5 at.% Si, d cast Al-5 at.% Ti, e nanocrystalline Al-5 at.% Cr alloys. Matrix (α) and secondary phases are marked

Fig. 3 SEM image for nanocrystalline Al-5 at.% Cr. Matrix (α*) and secondary phases are marked

Fig. 4 XRD patterns for cast Al-5 at.% Cr, cast Al-5 at.% Mo, cast Al-5 at.% Si, cast Al-5 at.% Ti and nanocrystalline (NC) Al-5 at.% Cr alloys

Fig. 5 a Potentiodynamic polarization curves for the cast alloys and nanocrystalline Al-5 at.% Cr in 0.01 mol/L NaCl (pH = 6.4), b potentiodynamic polarization curves for the cast alloys and nanocrystalline Al-5 at.% Cr in 0.01 mol/L NaCl (pH = 3)

Fig. 6 Corrosion current density for cast alloys and nanocrystalline Al-5 at.% Cr as determined from the potentiodynamic polarization tests

Fig. 7 Secondary electron images for a cast Al-5 at.% Cr (low magnification), b cast Al-5 at.% Cr (high magnification), c cast Al-5 at.% Mo (low magnification), d cast Al-5 at.% Mo (high magnification), e cast Al-5 at.% Si (low magnification), f cast Al-5 at.% Si (high magnification), g cast Al-5 at.% Ti (low magnification), h cast Al-5 at.% Ti (high magnification), i nanocrystalline Al-5 at.% Cr (low magnification), j nanocrystalline Al-5 at.% Cr (high magnification) alloys

Fig. 8 Vickers hardness measured for nanocrystalline Al-5 at.% Cr and pure Al, and estimated from rule of mixture for the cast alloys

Fig. 9 Vickers hardness number vs corrosion current density of cast alloys, nanocrystalline Al-5 at.% Cr and AA7075-T651