MICROSTRUCTURE EVOLUTION AND FEM ANALYSIS OF [011] ORIENTED SINGLE CRYSTAL OF A Ni-BASED SUPERALLOY DURING TENSILE CREEP

By means of the elastic stress-strain finite element method (FEM), the distribution features of the von Mises stress, strain energy density and the influences of the applied stress on the von Mises stress at γ/γ' phases interface and γ' phase directionally coarsening regularity in a 011] oriented single crystal nickel-based superalloy were investigated. Results show that after heat treatment, the microstructure of the superalloy consists of the cubic γ' phases embedded coherently in the γ matrix, and γ' phases arranged regularly along the <100> direction. Compared to the matrix channel near (010)γ' plane, the bigger von Mises stress are produced within the matrix channel near (001)γ' plane when the tensile stress is applied along the 011] direction. Compared to (010)γ' plane, the larger expanding lattice strain occurs on the (001)γ' plane along the 010]γ' direction under the action of the principal stress component, resulting in the Al, Ti atoms with bigger radius to be trapped by the larger strain zone, which is the main reason of promoting the γ' phase grown directionally into the strip-like rafted structure.