Stacking Fault Energies of Single Crystal Nickel-based Superalloy and Its Influence on Creep Mechanism

Abstract

By means of calculating stacking fault energy(SFE), measuring creep properties and contrast analysis of dislocation configuration, the influence of the temperature on the stacking fault energy and the creep mechanism of a single crystal nickel-based superalloy was investigated. Results show that there is a lower stacking fault energy(SFE) of the alloy at 760℃, and the deformed mechanism of the alloy during creep is the cubical γ' phase sheared by 〈110〉 super-dislocation which may be decomposed to form the configuration of (1/3)〈112〉 super-Shockley partials dislocation plus the super-lattice intrinsic stacking fault(SISF). But the stacking fault energy of the alloy increases with temperature, so the deformed mechanism of the alloy during creep at 1070℃ is the screw or edge super-dislocation shearing into the rafted γ' phase. The SFE of the alloy at 980℃ is in the middle value of the SFEs between 760℃ and 1070℃, the main deformed mechanism of the alloy during creep is the screw or edge super-dislocation shearing into the rafted γ' phase. And some super-dislocation shearing into γ' phase may cross-slip from {111} to {100} planes to form the K-W locks configuration of (1/2)〈110〉 partials plus the anti-phase boundary(APB). The K-W locks with non plane core structure may restrain the slipping and cross-slipping of dislocations to improve the creep resistance of alloy. Wherein, the lower strain rate during creep releases too less deformed heat to activate the dislocation in the K-W locks for re-slipping on {111} plane, which is thought to be the main reason of the K-W locks kept in the alloy during creep at 980℃.

Keywords

• single crystal nickel-base superalloy
• stacking fault energy
• creep
• contrast analysis
• deformation mechanism