Shearing of γ́ precipitates by a (112) dislocation ribbons in Ni-base superalloys : a phase field approach

Vorontsov, V.A. and Shen, C. and Wang, Y. and Dye, D. and Rae, C.M.F. (2010) Shearing of γ́ precipitates by a (112) dislocation ribbons in Ni-base superalloys : a phase field approach. Acta Materialia, 58 (12). pp. 4110-4119. ISSN 1359-6454 (https://doi.org/10.1016/j.actamat.2010.03.041)

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Abstract

The phase field model of dislocations has been used to study the propagation of dislocation ribbons with an overall Burgers vector of a(112) through a simulated Ni-base superalloy. The driving force for dislocation dissociation reactions and formation of planar faults isincorporated into the free energy functional using periodic functions specially fitted to ab initio γ-surface data. The model shows that the mechanism of cutting of the γ precipitates by these ribbons exhibits significant dependence on stress magnitude, orientation and precipitate shape. In the case of mixed screw-edge ribbons a change of shearing mode is observed, from stacking fault shear to anti-phase boundary shear, when the applied stress approaches the yield of the material. This transition is absent in pure edge ribbons.

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