Crystallographic Orientation Influence on the Serrated Yielding Behavior of a Single-Crystal Superalloy

Since Ni-based single-crystal superalloys are anisotropic materials, their behavior in different crystal orientations is of great interest. In this study, the yielding behavior in both tension and compression for ?001?, ?011? and ?111? oriented materials at 500 °C has been investigated. The ?011? direction showed a serrated yielding behavior, a great tension/compression asymmetry in yield strength and visible deformation bands. However, the ?001? and ?111? directions showed a more homogeneous yielding, less tension/compression asymmetry in yield strength and no deformation bands. Microstructure investigations showed that the serrated yielding behavior of the ?011? direction can be attributed to the appearance of dynamic strain aging (DSA) and that only one slip system is active in this direction during plastic deformation.