Simultaneous creep and oxidation of an Fe–5AL alloy at 973–1073 K

Studies of the simultaneous creep and oxidation of an Fe-5Al alloy at constant stresses of 12 and 16 MN m⁻² in the temperature range 973-1073 K have shown that the steady-state creep obeys a power law. The stress exponent n was found to lie between 5 and 7. The apparent activation energy for creep was in the range 77–397 kJ mol⁻¹ and depended on the oxygen partial pressure Po₂ of the test environment. The oxidation strengthening (steady-state creep rate ε decreasing) was found for an applied stress of 16 MNm⁻² for Po₂ in the range 10⁻⁷ to 1·013 × 10⁵ Pa. At 12 MN m⁻², strengthening occurred only in the range 973–1023 K; weakening was found at 1073 K. The primary causes of strengthening are believed to be the mechanical constraint of strongly adherent scales and internal oxide-dislocation interactions.

MST/133