Effect of structural order on oxidation kinetics and oxide phase evolution of Al–Zr alloys

Abstract To reveal the fundamental role of structural order of the parent alloy on the oxidation mechanism, thermal oxidation of amorphous and crystalline Al–Zr alloys with identical compositions were investigated in detail. An (Al0.68Zr0.32)O1.66 amorphous oxide emerged on crystalline Al2Zr, whereas an (Al0.33Zr0.67)O1.83 amorphous oxide formed on amorphous Al68at.%Zr32at.% under the same conditions. Oxidation kinetics was fast and linear for crystalline Al2Zr but slow and parabolic for amorphous Al68at.%Zr32at.%. The underlying mechanisms of such striking differences were disclosed by molecular dynamics simulations. The findings thus offer new prospects in the field of surface engineering.