Effect of the δ phase on the deformation behavior in isothermal compression of superalloy GH4169

► The effect of δ phase on the deformation behavior was reflected quantitatively. ► The existence of δ phase results in the increase of the m value and decrease of the n value. ► The existence of δ phase makes the n values reach a negative value at a small strain. ► The variations of m and n were found to be related to the microstructure evolution. ► The apparent activation energy of two kinds of treated superalloy GH4169 was studied.