Interfacial dislocation networks strengthening a fourth-generation single-crystal TMS-138 superalloy

Abstract

The ␥ /␥ Ј interfacial dislocation networks in several creep-ruptured superalloys were analyzed. It was found that the morphologies of dislocation networks differ slightly from each other in these alloys. The fourth-generation superalloy has finer dislocation networks and keeps a relatively stable state. Comparatively, the interfacial dislocations in the third-generation superalloy show obvious curved features associated with possible climb or slip. These interfacial dislocation characteristics can be correlated with the creep behavior of these superalloys. The mechanisms of evolution of the interfacial dislocation networks were discussed.

Joint Development of a Fourth Generation Single Crystal Superalloy

“…As will be shown, Ru was determined to be a critical element to the success of the alloy development program as it could be added to achieve both improved microstructural stability and increased high temperature creep strength. Subsequent alloy development efforts by others [4][5][6] have led to similar conclusions on the usefulness of Ru in 4 th generation single crystal superalloys.…”

New Single Crystal Superalloys, CMSX®-7 and CMSX®-8

“…Since introduction in the late 1970's, single crystal (SX) alloy development has generally focused on increased temperature capability, and major improvements in alloy performance have been associated with the introduction of new alloying elements, including rhenium (Re) and ruthenium (Ru) [1,2]. Rhenium has been widely used in advanced single crystal superalloys for turbine blade, vane and seal segments due to its potent effect in slowing diffusion and hence creep deformation and fatigue crack initiation under high temperature operating conditions [3].…”

Creep deformation behaviour of Rhenium free Ni-based single crystal superalloys LSC-15

“…The minimum creep rate decreases with the decrease of dislocation spacing in the γ /γ interface at each temperature. Zhang et al [5] described the relationship between the interfacial dislocation spacing, minimum creep rate and γ /γ lattice misfit at high temperature under low stress creep deformation. In the present study, the interfacial dislocation spacing at the corresponding minimum creep rate at 1000 • C and at 1050 • C were different.…”

“…In general, more refractory elements such as rhenium improve the creep resistance of the materials for advanced turbine blade [1][2][3][4]. It has also been reported that the γ /γ rafting behaviour is effective for creep resistance in case of the single crystal (SX) superalloys [5,6]. However, the price of rhenium, which is primarily consumed for the production of nickel base superalloys, has been substantially increasing for several years.…”