TEM and 3D atom probe characterization of DMS4 cast nickel-base superalloy

摘要

Cast nickel-base superalloys possess the required mechanical properties (creep resistance and stress rupture life) at elevated temperatures that make them suitable for turbine blades in aero-engines. The origin of these properties lies in the presence of a simple two phase γ–γ′ microstructure (with cuboidal γ′ particles dispersed in a γ matrix), in spite of the presence of several alloying elements. The cuboidal nature of the γ′ particles arises from an optimal misfit between the two phases, which is a function of the composition of γ and γ′ phases. In addition, several microstructural issues arising out of the partitioning of the alloying elements influences directly the deformation mechanisms in the γ and γ′, and therefore the mechanical properties of the alloy. In this article, we discuss how some of these microstructural issues have been investigated in DMS4, a cast single crystal superalloy, experimentally using TEM and 3DAP techniques.