DETERMINATION OF DIFFUSION CONSTANTS OF OXYGEN IN NICKEL AND ALPHA-IRON BY AN INTERNAL OXIDATION METHOD

The diffusion constants of oxygen in nickel and α-iron are calculated from experimentally determined internal oxidation rates in dilute silicon-bearing alloys. A single crystal alloy of composition 0.058 wt % silicon in nickel and polycrystalline alloys of composition 0.48 wt % silicon in nickel and 0.072 wt % silicon in iron were oxidised and allowance is made for the absorption of oxygen in the reaction with silicon. For nickel the values of activation energy Q=73.9 kcal/g atom in the range 800 to 1200° C and Q=74.4 kcal/g atom in the range 900 to 1300° C are in good agreement with a previous result. The activation energy required for oxygen diffusion in α-iron was found to be 39.9 kcal/g atom in the range 700 to 850° C. © 1969 Chapman and Hall.