Segregation effects on planar defects in crept Co-Al-W and Co-Ni-Al-W based superalloys
Creep deformation of γ/γ' microstructure superalloys involves shearing of γ' ordered phase that results in a high density of planar defects. These includes superlattice intrinsic faults (SISF), anti-phase boundaries (APBs) and micro-twins. Recently, in Co and Ni-based superalloys, the formation of these planar defects is shown to be associated with the local reordering and solute diffusion in their vicinity. These have been proposed to act as a rate limiting step for the creep deformation.
This project deals with the identifying the local atomic diffusional mechanisms occurring during creep of new Co and Co/Ni based superalloys by correlative techniques. These include controlled electron channeling contrast imaging (cECCI), high resolution and analytical transmission electron microscopy (TEM) and 3D atom probe tomography (APT) by utilizing a unique setup available at MPIE to get both compositional and crystallographic information of the planar faults.