PLASTIC DEFORMATION AND DISLOCATION STRUCTURE IN γ'-PHASE OF A DIRECTIONALLY SOLIDIFIED Ni-BASE SUPERALLOY
WEN Mao;LIN Dongliang T. L. Lin Shanghai Jiaotong University LIN Dongliang; professor; Shanghai liaotong University; 200030 Shonghai
Cite this article:
WEN Mao;LIN Dongliang T. L. Lin Shanghai Jiaotong University LIN Dongliang; professor; Shanghai liaotong University; 200030 Shonghai. PLASTIC DEFORMATION AND DISLOCATION STRUCTURE IN γ'-PHASE OF A DIRECTIONALLY SOLIDIFIED Ni-BASE SUPERALLOY. Acta Metall Sin, 1989, 25(5): 5-14.
Abstract The dislocation substructure of directionally solidified DS Rene 80superalloy during tensile deformation and during creep deformation has been studied byTEM. In tensile deformation, γ' shearing occurs by slip of APB-coupled 1/2<110>dislocation pairs on {111} planes at temperature below 760℃, and by slip ofSISF separated 1/3<112> superpartials which have dissociated on {111} planes intoa 1/2<110> screw superpartial and a 1/6<112> edge superpartial with an APB inbetween at temperatures above or equal to 760℃. In creep deformation, γ' shearingoccurs again by slip of SISF-separated 1/3<112> superpartials which have not dis-sociated on {111} planes and by diffusive slip of APB-coupled 1/2<110> disloca-tion pairs at 760℃ under a stress of 618 MPa. However, no γ' shearing occurs at980℃ under a stress of 190 MPa. During secondary creep at 760℃, 618 MPa orat 980℃, 190 MP8, walls of dislocations have been formed at γ/γ' interfaces, strainis controlled by climb of 2-dimensional dislocation netwotks at γ/γ' interfaces.The dependence of secondary creep rate, ε, upon size, α, and volume fraction, V_f,of cubic γ' has been found to be ε ∝ α/V_f~(2/3).
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