Creep Properties and Microstructural Evolution at 760°C/785MPa of a Re-Containing Single Crystal Superalloy

Abstract

Intermediate temperature creep properties are considered a key indicator of single crystal superalloys used for turbine blades of aircraft engines. The interrupted and ruptured creep tests were carried out in a second generation single crystal superalloy under the conditions of 760°C/785MPa. The creep rupture life as well as minimum creep rate were also in the same level of those in CMSX-4 and PWA1484. The microstructural evolution at different creep stages were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed the γ’ phases kept the cuboid morphology mostly until the creep rupture, and super lattice stacking faults (SSFs) extended along [-1 1 0] and [-1-1 0] orientations within the γ’ precipitate were the typical dislocation configuration.

Inhibiting creep in nanograined alloys with stable grain boundary networks

“…4). The creep resistances we observed in the NG-42 and deformed CG samples are obviously lower than those of conventional superalloys (2,17,(27)(28)(29)(30)(31)(32)(33)(34). The creep resistance of the SNG-9 sample is outstanding, with strain rates as low as ~10 -7 s -1 under a gigapascal stress at 700°C and 959 MPa at 750°C.…”

“…These properties in our single-phased NiCoCr alloy with stable GB networks are superior to the existing wrought single-phased and multiphased superalloys. Our alloy even outperforms that of the most heavily alloyed CMSX-4 ( 2 , 34 ) and SRR99 ( 33 ) single-crystal superalloys.…”

“…Creep data of the SNG-9 at 750°C are also included. Data of CMSX-4/SC are from the minimum uniaxial-tension creep at 750°C at 750 MPa ( 2 ) and 760°C at 785 MPa ( 34 ), respectively.…”