CROSS-SLIP AND DISLOCATION CLIMB IN NICKEL-BASE SUPERALLOYS

An investigation of the minimum creep rate of two nickel-base superall oys, with low volume fraction of precipitates gamma' has shown that tw o mechanisms were operative at the temperatures 923 and 973 K and an e xtensive range of applied stresses. The experimental data were interpr eted in terms of a new constitutive equation based on a creep model in volving dislocations cross-slip in the matrix and dislocation climb at high stresses over the strengthening phase. This analysis has been us ed to obtain microstructural parameters involved in the model such as activation area and stacking fault energy. The apparent activation ene rgy, Delta H-ap, measured by abrupt and small changes in temperature w ere analyzed. (C) 1997 Elsevier Science S.A.