In situ investigation with neutrons on the evolution of γ́ precipitates at high temperatures in a single crystal Ni-base super alloy

Abstract

Single crystal Ni-base super alloys based on the ã / ã′ system are widely used in gas turbine applications. To understand the formation of γ́ precipitates, including size distribution and growth, we performed in situ small-angle neutron scattering (SANS) measurements at elevated temperatures and -together with TEM as well as SEM imaging -studied changes in the precipitates in short and long time scale. In the early stages, a bimodal size distribution of precipitate is observed, which (depending on the annealing temperature) changes to a cuboidal or nearly spherical morphology with almost unmoral size distribution. © (2011) Trans Tech Publications, Switzerland.