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

摘要

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 effect. 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 interdiffusion of atoms between the different phases and the phases equilibrium in SC was changed. It is established that the interdiffusion rate depends on elements atoms activation energy. The new gamma-gamma'-eutectic pools were formed in the primary dendrites region (with fine gamma/gamma'-phase) and as result the length of newly formed dendrites was decreased significantly. The maximal and plastic depth of nanoindentation were measured and the corresponding micromechanical properties of phases calculated.