An Experimental Study of the Role of Plasticity in the Rafting Kinetics of a Single Crystal Ni-Base Superalloy

Abstract

Directional coarsening in a single crystal Ni-Al-MO alloy has been studied with varying pre-strain paths that alter the initial state of the y -y' interfaces. These microstructures were generated by pre-straining experiments at intermediate temperatures, maintaining the equiaxed morphology of the precipitates. Their subsequent evolution at high temperatures during ordinary aging as well as stress-annealing was examined by electron microscopy (SEM, TEM) and small-angle X-ray scattering (SAXS). These results are discussed in terms of the connection between the nature of the y -y' interfaces, the local stress state and the resulting driving force for rafting.