Effect of Hard Cyclic Viscoplastic Deformation on Phases Chemical Composition and Micromechanical Properties Evolution in Single Crystal Ni-Based Superalloy

Abstract

The phases chemical composition and micromechanical properties in single crystal of Ni-based superalloy with chemical composition of 12.1 Al, 5.3 Cr, 9.4 Co, 0.8 Nb, 0.9 Ta, 0.7 Mo, 2.5 W, 0.7 Re and Ni-balance (in at.%) were changed during hard cyclic viscoplastic deformation at room temperature. The method we used based on the Bauschinger eect. The changes in the dendritic microstructure and chemical composition were characterized by scanning electron microscopy and energy dispersive spectrometry. The phases micromechanical properties evolution were characterized by nanoindentation. The results show that the cumulative strain or strain energy density increase arouse the interdiusion of atoms between the dierent phases and the phases equilibrium in SC was changed. It is established that the interdiusion rate depends on elements atoms activation energy. The new γγ eutectic pools were formed in the primary dendrites region (with ne γ/γ -phase) and as result the length of newly formed dendrites was decreased signicantly. The maximal and plastic depth of nanoindentation were measured and the corresponding micromechanical properties of phases calculated.

Phase Equilibrium Evolution in Single-Crystal Ni-Based Superalloys

“…By this method, the cyclic stresses influenced the interdiffusion of elements and atoms between different phases. This method of SC Ni-based superalloy testing is called hard cyclic viscoplastic (HCV) deformation [28,39,44,46]. We estimated the microstructure evolution, phase equilibria shifts, chemical composition phase changes, and changes in the micromechanical properties of different phases in SC Ni-based superalloys during HCV deformation at room temperature.…”

“…Maximal stress values evolution of 30 cycles measured in sample S4 for tension-compression strain amplitudes of 0%-0.05%, 0%-0.2%, 0%-0.5%, and 0%-1%, respectively. Adapted from reference [46]. Phase Equilibrium Evolution in Single-Crystal Ni-Based Superalloys http://dx.doi.org/10.5772/61102 Figure 18.…”

“…The results from this nanoindentation ( Figure 23a shown near the indents. Adapted from reference [46].…”

“…Adapted from reference [46] The number and area of the γ-γ′-phase eutectic pools relative to the microstructure increased stepwise: S1, 1.05%; S2, 1.14%; S3, 1.86%; and S4, 2.06%. This development of the γ-γ′-phase eutectic pools is presented in Figure 27.…”

“…Mine directions of atom diffusion between phases in a cross-section of the primary axis is shown. Adapted from reference [46] the SC superalloy can be induced. Such defects form as a result of the high diffusion rate for Al in the Ni-based solid solution [47][48][49].…”