Temperature dependence of tensile behavior and deformation microstructure of a Re-containing Ni-base single crystal superalloy

• Published in: Materials & design 2017-09, Vol.130, p.131-139
• Main Authors: Wang, G.L., Liu, J.L., Liu, J.D., Wang, X.G., Zhou, Y.Z., Sun, X.D., Zhang, H.F., Jin, T.
• Format: Article
• Language: English
• Subjects: Deformation microstructure; Ni-base single crystal superalloy; Re-containing; Superlattice stacking fault formation; Tensile behavior; γ/γ' coherency relaxation
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2017.05.014

Tensile behavior of a Re-containing Ni-base single crystal superalloy with [001] orientation was conducted at from room temperature to 1100°C, and the corresponding deformation microstructure after fracture has been investigated by TEM. This alloy exhibits temperature dependent deformation microstructure and resultant tensile behavior. Shearing of γ' precipitates by dislocations, with respect to anti-phase boundary (APB) shearing and superlattice stacking fault (SSF) shearing, is mainly controlled by the interplay between γ/γ' lattice misfit, intrinsic strength of γ' phase and stress field of dislocations accumulated on γ/γ' interfaces. Below 800°C, the variation with temperature of (0.2%) yield strength is closely linked with the way of dislocations entering γ' precipitates, which is largely influenced by temperature dependent γ-γ' microstructure modifications. The tensile strength at 1100°C is determined by gliding-climbing of dislocations, with the help of thermal activation, in obviously modified γ-γ' microstructure. In fact, flow stresses at 800°C and 1100°C drop remarkably with the onset of numerous APB shearing of γ' particles after γ/γ' misfit stresses are relaxed by depositing dislocations. Last, thermally-activated and plasticity-induced γ-γ' microstructure modifications are taken into account to elucidate the deformation microstructure and resulting tensile behavior of this Re-bearing alloy at various temperatures. [Display omitted] •Plasticity is mainly contolled by γ channel width, γ/γ' lattice misfit and γ' intrinsic strength at every temperature.•Stacking fault formation below 800°C is largely influenced by temperature dependent γ/γ' misfit and γ' intrinsic strength.•Flow stresses at 800°C and 1100°C drop remarkably with dislocations entering γ' particles after γ/γ' misfit relaxation.•Thermally-activate and plasticity-induced γ-γ' modifications explain deformation miscrostructure and tensile behavior.