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The dislocation structure of directionally solidified(DS)Rene 80 superalloy during tensileand creep deformation has been studied by TEM.In tensile deformation,γ’shearing occurs byslip of APB-coupled(1/2)<110>dislocation pairs on{111}planes at temperatures below760℃.and by slip of SISF-seperated(1/3)<112>superpartials which have dissociated on{111}planes into a(1/2)<110>screw superpartial and a(1/6)<112>edgesuperpartial with an APB in between at temperatures equal to or above 760℃.In creepdeformation,γ’shearing occurs again by slip of SISF-seperated(1/3)<112>superpartialswhich have not dissociated on{111}planes and by diffusive slip of APB-coupled(1/2)<110>dislocation pairs at 760℃,618 MPa.However,no γ’shearing occurs at 980℃,190MPa.During secondary creep at 760℃,618 MPa or at 980℃,190 MPa,2-dimensional net-works have formed at γ/γ’interfaces,and the strain is mainly the result of diffusion control-led climb of dislocation networks at γ/γ’interfaces.The dependence of secondary creep rate εupon size a and volume fraction v_■ of cubic γ’ has been found to be ■∝α/v_f~(2/3).
The dislocation structure of directionally solidified (DS) Rene 80 superalloy during tensile and creep deformation has been studied by TEM. Tensile deformation, γ’shearing occurs by slides of APB-coupled (1/2) <110> dislocation pairs on {111} planes at temperatures below 760 ° C and by slip of SISF-seperated (1/3) <112> superpartials which have dissociated on {111} planes into a (1/2) <110> screw superpartial and a (1/6) <112 > edgesuperpartial with an APB in between at equal to or above 760 ° C In creepdeformation, γ’shearing occurs again by slip of SISF-seperated (1/3) <112> superpartialswhich have not dissociated on {111} planes and by diffusive slip of APB-coupled (1/2) <110> dislocation pairs at 760 ° C, 618 MPa. No, γ’shearing occurs at 980 ° C, 190 MPa. MPa, 2-dimensional net-works have formed at γ / γ’interfaces, and the strains is mainly the result of diffusion control-led climb of dislocation networks at γ / γ’interfaces.The dependence of secondary creep rate εupon size a and volume fraction v_ ■ of cubic γ ’has been found to be ■ αα / v_f ~ (2/3).