HIGH-TEMPERATURE X-RAY MEASUREMENTS OF THE LATTICE MISMATCH OF CREEP-DEFORMED MONOCRYSTALS OF THE NICKEL-BASE SUPERALLOY SRR-99

The investigation of X-ray line profiles of deformed and undeformed samples of the nickel-base superalloy SRR99 shows that residual long-range internal stresses act in the phases γ and γ′. During the high-temperature measurements, the linewidth, corresponding to the deformation-induced distortions in the phases γ and γ′, decreases at temperatures above about 800 °C, while the deformation-induced counteracting internal stresses in the hard γ′-phase and the soft γ-phase start to decrease above 900 °C and vanish at 1050 °C due to recovery. Thermally induced internal stresses related to the anisotropic raft-like plate structure decrease during heating to high temperatures and are built up again, when the samples are cooled back to room temperature. The investigation of the high-temperature X-ray line profiles gives important information on the interaction of internal stresses which are built up by different mechanisms. © 1995.