Spontaneous deformation during the high temperature oxidation of Fe-20Cr-5Al-(0, 0.06)La alloy thin strip

Growth stress and spontaneous deformation in Fe-20Cr-5Al-(0, 0.06)La alloy thin strip oxidized at high temperature have been studied. The spontaneous deformation of the metal substrate was considered as creep behavior. The activation energy for the creep was determined from the relationship between the strain rate and the reciprocal oxidation temperature. La free alloy thin strip showed an activation energy of 332 kJ/mol. A compressive stress of 652 MPa and tensile stress of 10 MPa have acted on α-alumina oxide film and metal substrate, respectively. These growth stresses were relaxed through not only the creep of the metal substrate but also the local detachment of α-alumina oxide film from the metal substrate. La added alloy showed an activation energy of 263 kJ/mol, which was lower than the activation energy in La free alloy. No cracking or fracture in α-alumina oxide films was found. The addition of La seemed to assist the progress of the stress relaxation through the creep of the metal substrate.