| Four kinds of Cu-Ni alloys(90Ni-Cu, 78Ni-Cu, 10Ni-Cu) were crept to investigate the effect of solute atom on the creep behavior of these alloys over the temperature range of 558-676K(0.4T_m where T_m is the absolute melting temperature) and at the stress levels from 127 to 256 ㎫. Results show Chat the static and cyclic creep deformation behaviors are affected by the thermodynamic factor, 1-(d ln γ_i/d lnX_i), Where γ_i and X_i are activation coefficient and compositional concentration, respectively. Cyclic creep acceleration is observed for 40Ni alloy under the stress of 197 ㎫, and it can be explained that the excess vacancies generated mechanically under cyclic creep assist the recovery process with dislocation climb. To illustrate the above results, a proper creep equation is proposed as, ε˚=K(1/b²)(γ/Eb)³(D₁.+f_PD_P)(σ/E)³(T.F.), where E is Young`s modulus, b is Burgers vector, r is stacking fault energy, D_L is lattice diffusion coefficient, D_p is pipe diffusion coefficient and T.F. is thermodynamic factor. |
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