On the formation of 〈010〉-dislocations in the γ′-phase of superalloy single crystals during high temperature low stress creep

Abstract

The cutting of γ′-particles by dislocations during shear creep deformation of CMSX 6 superalloy single crystals loaded on the macroscopic crystallographic shear system 〈110〉{111} at T = 1025°C and τ = 85 MPa is analysed using transmission electron microscopy (TEM). The formation of a 〈010〉-dislocation in the γ′-phase was observed and investigated by means of stereo microscopy, line trace and g·b-analysis. Two γ-matrix channel dislocations with different Burgers vectors ( b) of type α 0/2〈110〉 jointly shear the γ′-particle where they form a superdislocation with a total Burgers vector of α 0〈010〉. The present paper provides microstructural evidence for this high temperature cutting process. The results are discussed in relation to the evolution of the dislocation structure in the γ-channels during primary creep. Peach-Koehler forces were calculated to explain the formation of the 〈010〉-dislocation.