Rafting and elastoplastic deformation of superalloys studied by neutron diffraction

The rafting of monocrystalline Ni- and Co-based superalloys has been studied by neutron diffractometry. Lattice parameter misfit values and the difference in phase stiffnesses at room temperature, 650 °C, and 900 °C are presented. These microstructural parameters should assist in refining computer models that aim to predict precipitate evolution in superalloys and aid future alloy design. The nature of rafting is shown experimentally to be dependent upon the lattice parameter misfit. The 900 °C yield strength of the γ-phase of the Co-based superalloy with a rafted microstructure occurs at ∼ 100 MPa, when loaded at a low strain rate.