Corrosion Behavior and Hardness of Al-M (M: Mo, Si, Ti, Cr) Alloys

The corrosion behavior of Al-5 at.% Cr, Al-5 at.% Si, Al-5 at.% Mo and Al-5 at.% Ti produced via casting and Al-5 at.% Cr produced by high-energy ball milling and subsequent consolidation by cold pressing was studied using potentiodynamic polarization and surface analysis following constant immersion tests. Alloys were characterized using a scanning electron microscope coupled with the energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. Hardness, a representative of the strength, was also measured. The alloys produced by casting contained coarse inter-metallics and therefore exhibited poor corrosion resistance. Al-5 at.% Cr alloy produced by high-energy ball milling exhibited a significantly improved corrosion resistance and hardness, which was attributed to the grain refinement to nanoscale and extended solid solubility of Cr in Al. The study indicated that the high-energy ball milling was capable of producing Al alloys with improved corrosion behavior and hardness.