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 degrees 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.