Creep properties of Ag–2 wt% Cu alloy in the solid solution region

Abstract

Creep properties of Ag–2 wt% Cu samples with different grain diameters were studied at different temperatures ranging from 573 to 723 K under constant applied stresses ranging from 24 to 36 MPa. The transient creep parameters β and n showed a remarkable dependence on the grain diameter d of the tested samples, deformation temperature T and the applied stress σ. The grain diameter dependence of the steady state creep rate ε ˙ st was found to satisfy a Petch type relation; έ st = a + bd 2. Moreover, the stress dependence of ε ˙ st was found to satisfy the stress power law; έ st = Cσ m. The stress exponent m was found to increase with increasing both d and T. The energy activating the creep process in the transient and the steady state stages ranged from 0.21 to 0.45 and from 0.45 to 0.95 eV, respectively, suggesting that glide of dislocations to be the mechanism operating in the transient stage and climb and/or viscous glide to be the controlling mechanism in steady state stage. The results were analyzed and discussed in view of the microstructure examination by the energy dispersive X-ray spectroscopy (EDX) and optical microscope.