Selective Oxidation of Al from an Al -Fe Alloy

The selective oxidation of aluminum from a 4.8 wt % Al‐Fe alloy was studied with a microbalance at temperatures of 700°–900°C. The oxidizing gas was damp H 2 , with dewpoints ranging from −55° to 0°C. The oxidation product was identified by electron diffraction to be the crystalline spinel, γ ‐ Al 2 O 3 . At 800°C the parabolic oxidation constant was approximately proportional to the 1/7th power of the H 2 O / H 2 gas ratio, and the experimental activation energy for the over‐all oxidation reaction with 0°C dewpoint hydrogen gas was 72 kcal/mole.