Creep-rupture behavior of a nickel-based single crystal superalloy

Abstract

A first generation single crystal superalloy was employed to research the high temperature creep behavior. Scanning electron microscope (SEM), transmission electron microscope (TEM) are used. The main results are summarized below: There are two mechanisms for the steady creep. The first one is superlattice dislocation cutting γ′ precipitates, which is the main mechanism for 1000°C creep behavior. In this case, the creep rate increases when the γ/γ′ microstructure undergoes topological inversion, which leads to a rapid increase in the density of γ′ cutting dislocation. The second mechanism is transverse climb of a/2<110> interfacial dislocation, which is the main mechanism for 1100°C creep behavior. In this case, climb of interfacial dislocations produced most of the steady creep strain. A by-product is the vacancies diffusing along the interfaces and low angle boundary to pores.