Two-stage relaxation of damage structure in strongly creep-deformed single crystal superalloy SC16 measured by means of X-ray diffraction

Specimens of single crystal superalloy SC16 were creep-strained at 1223 K along the [0 0 1] direction up to rupture using a creep stress of 150 MPa. After creep strain, structural changes were monitored by X-ray diffraction measuring fundamental and superlattice reflections. Measurements were performed in the temperature range between room temperature and 1173 K as a function of temperature and time. The data indicate two relaxation processes which are ascribed to thermally activated rearrangement of damage structures created during creep deformation.