Measurement of γ′ precipitate morphology by small angle neutron scattering

Abstract

Modern Ni-base superalloys contain large volume fraction of ordered Ni{sub 3} (Al, Ti) precipitates ({gamma}{prime} phase) which are coherently embedded in a Ni-Al solid solution ({gamma} phase). Superalloys are strengthened by the {gamma}{prime} precipitates and it is known that the precipitate morphology, their distribution in the matrix and their volume fraction strongly influence the strength of the alloys. In this paper the authors results from the measurements by small angle neutron scattering (SANS) and use special data analysis procedures to quantify various {gamma}{prime} morphological parameters. The authors use complementary measurements by scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) to verify and augment the results of SANS. They find SANS is a very useful tool for these kind of measurements as it measures over a large volume of specimen. Further, the 3-Dimensional microstructural parameters could be obtained quantitatively from measurements on a single specimen with the help of a cradle used to in-situ align the specimen with respect to the neutron beam.