Effect of an applied stress on the growth kinetics of oxide scales formed on Ni-20Cr alloys

The effect of a tensile load on the oxidation rate and mechanism of Ni-20Cr was studied at 600 and 900 degreesC by comparing samples oxidised in air e ither classically or under tensile creep. The objective was to understand t he simultaneous effect of the environment and mechanical loading. Applying a tensile load does not modify the oxide layer nature but the oxidation rat e is enlarged due to the increase of oxygen diffusion via fast diffusion pa ths generated when the strain is higher than a critical value. Thus, at 600 degreesC, oxygen in excess promotes internal oxidation and the oxide layer s are thicker than when formed without any load. At 900 degreesC, for small oxidation times, the spinel layer is enlarged, while for longer times, the spinel layer progressively disappears and the excess of oxygen diffusing i nward reacts with chromium to form a thicker Cr2O3 layer.