SIMULTANEOUS CREEP AND OXIDATION OF AN FE-5AL ALLOY AT 973-1073-K

Studies of the simultaneous creep and oxidaton of an Fe-5Al alloy at constant stresses of 12 and 16 Mn m** minus **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** minus **1 and depended on the oxygen partial pressure p(O//2) of the test environment. The oxidation strengthening (steady-state creep rate epsilon decreasing) was found for an applied stress of 16 MN m** minus **2 for p(O//2) in the range 10** minus **7 to 1. 013 multiplied by 102**5 Pa. At 12 MN m** minus **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.