Phase field modelling of stacking fault shear in nickel base superalloys

Vorontsov, V. A. and Rae, C. M. F. and Voskoboinikov, R. and Shen, C. and Wang, Y. and Dye, D. (2008) Phase field modelling of stacking fault shear in nickel base superalloys. In: Dislocations 2008, 2008-10-13 - 2008-10-17, Hong Kong Gold Coast Hotel.

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Stacking fault shear (SFS) is the dominant creep deformation mechanism in Nibase superalloys subjected to primary creep conditions (750°C, 800MPa). TEM observations1 have shown that the source of plastic strain is the shearing of they' precipitates by dislocation ribbons with overall burgers vector of a< 112 >. SFS can only occur when they matrix is sufficiently saturated with a/2 < 110> dislocations. These matrix dislocations are unable to cut the y' because of the high energy APB they leave in their wake. By combining into a ribbon, shearing of the precipitates is facilitated by formation of intrinsic and extrinsic stacking faults (SISF and SESF).