I don't understand this graph. From the graph, does it mean that at high pressures the oxide layer is stable and this stability reduces at low pressures and temperatures?
1 Answer
The graph does show that at high pressures the $\Delta G$ per surface area values are lower, which would usually indicate stability. I agree with you that as the pressure goes lower, the stability reduces.
However I disagree regarding temperature: As the temperatures decrease (from the green curve denoting 1500K to the blue curve denoting 300K), the $\Delta G$ values are going down, meaning an increase in stability.